A

AAA: American Automobile Association. This is the large nationwide car club that offers services such as travel assistance, roadside service.  AAA was once the organization that sanctioned most of the "legitimate" racing in the United States; its Contest Board sanctioned the Indy 500 and all Indy car racing in the U.S. until 1955 (when the Contest Board was disbanded). AAA is no longer involved in racing, but actions that it took in the '40s and '50s led indirectly to the formation and growth of NASCAR and USAC, and the ramifications of those actions are still with us today.
AARA: Antique Auto Racing Association. Sanctions Vintage Open Wheel exhibition racing. 
ABC: Refers to the progression of a stock car drivers training or career through three specific series, A-ARCA, B-Busch, and C- (Nextel) Cup.
ABC Money: Awards given to drivers or team owners who participate consistently in a series.
Abrasion: The act of or effects from friction or stress between two surfaces.
ABS: Anti-Lock Braking System. Anti-lock brake systems are designed to sense wheel locking before it occurs and then release the brakes so that loss of control does not occur..
ACCUS: Automotive Competition Committee of the United States. This is an umbrella organization, which includes representatives from CART, NASCAR, IMSA, SCCA, NHRA, USAC, and as of November 1997, the IRL. It handles cross licensing between sanctioning bodies in the U.S., and serves as the U.S. representative to FISA, the international auto racing coordination body.
ACES: Atlantic Coast Enduro Series.
Ackerman: The effective change in toe angle as the wheels are turned through their range of steering motion. This value is described in percentages of change. Frequently confused with bump steer.
ACOT: Atlantic Coast Old Timer Racing Club. 
ACRL: American City Racing League.
ACT: American-Canadian Tour, a former rival to ASA. ACT was similar to, but smaller than, ASA; they sanctioned similar classes of cars, mainly in the Upper Plains and central Canada. Tom Curley, the sanctioning body's owner, shut it down at the end of the 1995 season.
Adding Spoiler: Changing the direction of a wing or spoiler to add more downforce.
Adhesion: The amount of stick between two surfaces. Adhesion usually applies to objects at rest where traction applies to objects in motion.
Aero: Abbreviation used when referring to aerodynamics.
Aerodynamic Balance: A state of equilibrium between the front and rear aerodynamic downforce.
Aerodynamics: The science studying the forces exerted on racecars surfaces by air in motion and how it affects downforce, drag, and lift.
Aero Grip: Traction provided by down forces applied to the car’s surfaces and transferred to the tires.
Aero Loose: When two cars are close together and the lead car has less air being applied to its rear spoiler. This causes the car to have less rear downforce, which causes it to be loose in the turns.
Aero Push: When two cars are close together and the trailing car has less air being applied to its nose. This causes the car to have less front downforce, less turning ability, which then causes the car to push up the track.
AFCS: American Funny Car Series. Sanctions Drag Racing in the United States. Formally known as United Drag Racers Association.
After Market: Generally, the replacement parts and high performance products market.
AFR: Abbreviation for Air/Fuel Ratio. The mass of air inducted divided by the mass of fuel inducted.
A-Frame: Either the upper or lower connecting suspension piece locking the frame to the spindle.
Agricultural Racing or Excursion: When a car leaves the track and runs through the grass.
AHDRA: All Harley Drag Racing Association.
AHRA: American Hot Rod Association. Sanctions Drag Racing in the United States.
Air Box: Housing for the air cleaner that connects the air intake to the carburetor.
Air Dam: Used to direct or block airflow. Located on lower front valance. Used in front to prevent airflow to undercarriage, intended to prevent turbulence and lift.
Air Filter: Element used to keep particles from entering the carburetor and engine.
Air Foil: A stabilizer, generally used to create down forces, increase stability, and tire-to-track adherence at high speeds.
Air Pressure: The amount of air inside the tire pressing outward on each square inch of tire; expressed in pounds per square inch (psi) or kilopascals (kPa), the metric designation for air pressure. This should be expressed in "cold" or "hot" values and varies with atmospheric conditions.
Air Wrench: In general, any power wrench powered by compressed air, but often used to refer specifically to the special power wrenches used to change tires during a pit stop. 
AIS: The American Indy car Series, a low-cost series for Indy car racing. This series keeps costs low by using cast-off CART cars and by using an engine equivalence formula allowing teams a wide variety of engine choices. Currently, the series is defunct, but existing cars are still used in vintage competition.
Alcohol: When used to refer to racing car fuel, nearly always means methyl alcohol, or methanol. Ethanol is very seldom used for racecars (it costs too much), and other types are never used.
Alignment: The state in which all wheels on a vehicle are pointed in the optimum direction relative to the chassis.
All Pro: A touring series for Late Model cars, running mostly in the South. Created by super-promoter Bob Harmon, who sold the rights to the series to NASCAR in 1992. All Pro cars are quick and light, and often have much higher cornering speeds than other racecars on the same track. At one time, All Pro cars were notorious for high cornering speeds which resulted in boring, one-groove racing, but in the last few years NASCAR has made rules changes to correct this situation. Series was renamed the Kodak Southeast Tour in 2003.
All-Season Tires: Passenger car tires that are designed for use on dry and wet pavement, and also provide traction in snow and ice. 
Alphanumeric: A term for describing something using both letters of the alphabet and numbers. Used in describing tire sizes.
Altered: A general description of a racing vehicle featuring an open cockpit, tubular frame, center driving position, and altered, cut down body from a passenger vehicle. Popular altered body styles were originally produced overseas including the Anglia, Fiat, and Bantam. Can also refer to a car or portion of a car that has been changed in some way.
Alternate Starter: A practice, which used to be common in oval-track racing but has now just about died out. An alternate starter was the fastest (or sometimes the two or three fastest) among the cars that did not qualify for the race. Many races used to have rules that substitution of cars or drivers after qualifying was not permitted; if a driver crashed his car after qualifying, or were otherwise unable to start the race, that driver and car would have to withdraw. In this event, an alternate starter would be added to the field to take the place of the withdrawn team.
Alternator: A belt-driven device mounted on the front of the engine that recharges the battery while the engine is running.
AMA: American Motorcyclist Association. Sanctions Motorcycle events throughout the United States.
Amateur: A beginner or novice in the sport. It is the opposite of Professional.
Ambient Temperature: The temperature of the surrounding air.
AMRA: (1) American Motor Racing Association. Sanctions Open Wheel Modified racing in the US and Canada. (2) American Motorcycle Racing Association. 
AMSA: American Mini-Sprint Association.
Angle of Attack: The angle of a car or wing relative to the direction of travel.
ANRA: American Nostalgia Racing Association. Sanctions Nostalgia Drag Racing.
Anti-Sway or Anti-Roll Bar: A suspension component that links the left and right side suspension movement together. This is a torsion spring that limits the amount of lean that a vehicle will develop in a turn. It can be used in either the front or rear of a vehicle. It is a primary tuning device for handling characteristics. Also called "sway bar," roll bar, and anti-roll bar.
AOAS: American Outlaw Action Series.
Apex: The point in a turn where the car is turning most sharply. By definition, the apex is usually the slowest part of the turn; the car slows down into the apex, and then accelerates out of it. (However, this rule is sometimes violated by the use of unusual cornering techniques.) See also diamonding. Some turns on road courses may require more than one apex.
A-Post: The post extending from the roofline to the base of the windshield on either side of the car.
Appearance money: A guaranteed payment from the promoter or sanctioning body to a driver or team just for showing up, regardless of how that driver or team does in the race. Programs with names like "Winners' Circle" or "Appearance Plan" which pay per-race bonuses to drivers or teams, which have been regular entrants and have run well in the promoter's events or series.
Apron: An area on the inside of the track for cars that are going slowly. At high-banked tracks, the apron has less banking, so that cars that aren't up to speed won't slide off. The apron is also used as the approach to the pits, and as the merge-in area for cars exiting the pits. See also warm-up lane.
A/R: The size of a turbochargers turbine housing. “A” refers to the area of volute at a specific cross-section; “R” is the radius of the center of that area.
Aramid: A synthetic fabric used in some tires that is (pound-for-pound) stronger than steel. Example: Kevlar
ARCA: Auto Racing Club of America. Sanctions a national Stock car series, and several regional series. Founded in 1953 as the Midwest Auto Racing Club, it has evolved a number of regional racing series in the Midwest and West over the years. Its national series, the ARCA Supercar series, has the distinction of being the only nationwide Stock car racing series today that runs on both paved and dirt tracks. ARCA has a longstanding relationship with NASCAR, and some of its races are run as support events for Winston Cup races. Many up-and-coming drivers use ARCA to get superspeedway experience, since they run more superspeedway events than BGN does.
ARCA Invaders: Derogatory name for NASCAR teams or Drivers that enter in an ARCA Series event.
ARDC: American Racing Drivers Club.
Arm Restraints: Straps that attach to a driver's arms to limit the range of motion of the upper arm and by doing so keep the forearms and hands in the car. Sometimes required in Sprint and Midget racing; these cars are capable of flipping and rolling very violently, and the arm restraints keep the driver's arms from slipping out of the roll cage and getting crushed by the car in a roll. Similar to the purpose served by the window net in a Stock car.
Armco: A brand name for one brand of corrugated steel barrier widely used for guardrails on highways. In the '70s, many racetracks experimented with using Armco instead of concrete for crash walls. In this application, the steel barriers have been largely unsatisfactory, too easily damaged and in need of frequent repair. (Also, they are unsightly when damaged.) For this reason, most tracks are now phasing Armco out, in favor of concrete walls.
ARPI: Auto Racing Promotions.
ASA: American Speed Association. Sanctions a Stock car series (the ASA Racing Series) that operates mostly in the Midwest and Southeast, although they have enough dates in other parts of the country that their series is usually considered national. Since 1992, this series has been an innovator in reducing the cost of participation, and many regard it as being the prototype for the future of Late Model type racing. In addition, ASA sanctions weekly racing at tracks mainly in the Midwest. Founder Rex Robbins sold ASA to Georgia businessman Steve Dale in 2003.
ASCA: Arizona Sprint Car Association.  
ASCC: Atlantic Sports Car Club.
ASCoC: All Star Circuit of Champions. Sanctions Sprint car racing in the United States.
ASCS: American Sprint Car Series. Sanctions Sprint Car racing in the United States.
ASCT: Alaska Sprint Tour. 
ASM: All Star Midgets. Sanctions Midget and Dwarf car and Modified Lite Racing.
Aspect Ratio: Tire size term used to compare the tire width to the sidewall height. It is a percentage of the sidewall height compared to the tire width.
ASRTS: All Star Race Truck Series.
ASSC: Alaska Sports Car Club.
Assembly: Typical description of a wheel and tire unit. This can include a tube or liner as well.
Associate: A sponsor that puts up a small amount of money for a race team, and consequently gets its name on a less visible area of the car (such as the rear bumper, or the B-pillar between the side windows).
Atmo Engine: Engines, which use natural or atmospheric airflow as opposed to forced induction. NASCAR, Formula One and NHRA Pro Stock cars use "atmo" engines while Indy and NHRA Top Fuel and Funny Car engines use forced induction engines.
ATQMRA: American TQ Midget Racing Association.
Attenuator: A device mounted at the rear of an IRL car to absorb impacts to the rear end. The IRL new cars originally had a problem with the rear of the car being very stiff and transmitting rear-end impacts to the driver, and the attenuator (which is a large block of neoprene rubber) was an attempt to alleviate the problem. The rear-end stiffness problem has since been solved, but the attenuator remains as an additional safety device.
Attrition: The rate at which cars drop out of a race, due to mechanical failure or wrecks. Attrition is said to be high when few of the cars that start a race finish it.
Australian Pursuit: An odd form of racing which was popular in the early days of stock car racing, but has just about disappeared now. In Australian pursuit, each car that is passed by any other car during the race is black-flagged and eliminated from the race. The winner is the last car left on the track (or the first car to finish out of those remaining after a certain number of laps). Australian pursuit is usually considered to be a novelty event.
Autoclave: A complex oven for curing parts made of carbon fiber.
Axle: The pole or shaft on which a wheel turns. Rotating shafts connecting the rear differential gears to the rear wheels. Drive unit connecting the transmission to the front hubs on front drive vehicles
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B

Back Gate: Literally, the gate on the back stretch at a short track where car trailers or transporters are let into the pits or garage area, but the term is used by promoters to mean the number of cars and teams that actually show up and attempt to qualify for a race. It's an axiom in the racing industry that the back gate (number of participating cars) has a direct effect on the front gate (number of paying spectators), and so good promoters work hard at keeping their back gate as high as possible.
Backing It In:  Term used to describe a non-wing sprint car's entry into a corner. The car enters the turn in a slide with the rear of the car leading the front of the car. Also refers to a crash involving the car going back first into the wall.
Back Pedaling: Most commonly used in drag racing, the magical art of a driver easing out of the throttle to regain traction and avoid or stop tire shake. Difficult to achieve, the driver must anticipate the problem and pedal before the car is too far out of shape, all in less than 1/2 of a second.
Back Marker: A car that is many laps behind in a race. Also used as a derisive term to refer to drivers who are consistently slower then the majority of the field.
Back Out or Back Off: When a driver takes his foot off the gas pedal and slows down.
Back Stretch: The straightaway on a common oval track found between turns 2 and 3 on the opposite side from the start/finish line.
Backup Car: A complete second car used if a team’s first car is damaged.
BADGER: Badger sanctions Midget racing.
Bag Tank: Deformable fuel tank made from high strength rubber that is designed to flex and not rupture during an accident.
Balaclava: See head sock. Nomex or fireproof fabric for head and face protection
Balanced: The state in which a tire and wheel spin with all their weight distributed equally. Also refers to a cars setup being correct.
Ballast: A controlled amount of weight, functionally positioned, used to help car meet class weight requirements.
Ball Joint: A component of the front suspension consisting of a ball mounted in a socket that allows steering control in a stock car.
Bank/Banking: As applied to racetracks, the angle from the horizontal at which a corner or straight is tilted. Banking a corner increases cornering speed by converting some of the sideways centrifugal force to downward force, in much the same way that an airplane banks to make a turn. (It also improves drainage.) Bank is measured in angular degrees from the horizontal. The highest-banked track in the U.S. currently being used for racing is in Bristol, TN; it has 36-degree banking in the corners. The highest-banked superspeedway is Talladega, with 33-degree banking. Daytona has 31-degree banking. (By comparison, Indianapolis has only 9-degree banking, so it is not true that "superspeedway" is synonymous with high banks.)
Barge Board: Aerodynamic device placed in front of the sidepods or a suspension piece to smooth the airflow.
Barnstorming: Staging of an informal series of races by a touring group, often on temporary or jury-rigged racetracks. Many barnstormers engaged in hippodroming. A popular form of racing in the '30s and '40s when race cars were rare and sanctioning bodies were rarer, barnstorming has just about died out now in the U.S., although there are still some touring groups staging events such as stunt shows and demolition derbies.
BCRA: Bay Cities Racing Association.
BDC: Abbreviation for Bottom Dead Center. The position of the piston at the bottom of its stroke.
Bead: A round hoop of steel wires, wrapped or reinforced by ply cords, that is shaped to fit the rim; holds the tire onto the rim.
Bead Lock: A device used on some short-track racing cars to positively fasten the tire bead to the wheel rim. Particularly with low-pressure tires often used on dirt tracks, a bead lock keeps the tire on the wheel, and prevents the tire from slip rotating around the wheel, which can cause the bead to break.
Bead Wire: The steel wire wrap that is used to construct the bead package.
Beauty Bar: Design treatment that typically separates the sidewall from the shoulder of a tire.
Behind the Wall: Referring to taking a car into the garage area behind the pit wall to do major repairs.
Bell Housing: A cover shaped like a bell that surrounds the flywheel and clutch that connects the engine to the transmission.
Belly Pan: Generally, a skin of aluminum or fiberglass used to cover the under carriage of vehicle, assisting in preventing turbulence and air drag.
Belt: A rubber-coated layer of cords that is located between the plies and the tread. Cords may be made from steel, fiberglass, rayon, nylon, polyester or other fabrics.
Belted Bias Tire: A pneumatic tire with a body similar to that of bias tires, but which also includes two or more belts under the tread.
Belt Line: The line running around a cars body formed by the bottom edges of its glass panels.
Belt Package: The entire grouping of belts in a tire.
Bench Racing: Talking about racing; what racers and race fans do in the winter, or any other time when there's no real racing going on.
Bend: A shallow turn in the track.
BGN: The NASCAR Busch Series, previously known as the Busch Grand National. A Stock car series sanctioned by NASCAR. The cars are similar to Winston Cup cars, the main differences being smaller carburetors, less horsepower, and prohibitions on exotic materials.
Bias Ply Tire: Bias Ply tires are constructed of layers of rubber-coated plies composed of textile cords placed upon each other at approximately 30-45 degree angles. These plies are then wrapped around the bead wires. As a result of a tire being bias in design it will have a circumference that varies from tire to tire. Because of its design a bias tire can expand due to increased air pressure or due to heat generated during use. This allows a team to tune their cars setup and stagger in order to help the car handle better. Bias-ply tires have many limitations. Since the plies were placed at angles to each other, the casing is subjected to strong friction due to inter-ply shearing, which builds up heat and increases tread wear due to a higher slip angle. The positioning of the plies also limits the tire’s ability to provide both superior handling and ride comfort. One big advantage of bias tire is the lower tire cost. Bias tires are also much more tolerant of the set up than radial tires. It is easier to set them up and they are typically easier to drive at the limit of traction. Bias ply tires like higher slip angles, in the area of 3°-5° and work best with less than 1 degree of camber.
BIDCA: Badger-Illini Classic Modifieds. 
Big Block: As used today, usually refers to a big-block Chevy engine, although in context it can refer to a big-block engine from any manufacturer. Background: In the 1960, American manufacturers commonly sold all cars except for their economy lines with V-8s; engines of various displacements were created from the same basic engine block by using different bore, stroke, and cylinder head measurements. However, when consumers begin to demand more powerful, larger-displacement engines in the '60s, makers found that there were limits to the displacement that could be gained by adjusting bore and stroke, and so they each designed a second, larger block design for these larger-displacement engines. So, racers begin referring to the two V-8 block designs from any particular manufacturer as their "small block" and "big block". Generally, the small block was used for engines ranging from 250 to 400 cubic inches (4.0 to 6.3 liters), and the big block was used for engines of larger than 400 cubic inches. Big blocks are seldom used for production vehicles today (some larger trucks being the main exceptions), but some blocks are still manufactured in low quantities for racing.
Big One, The: Refers to a wreck involving many racecars during a race usually at one of the bigger speedways such as Daytona or Talladega.
Billet: Raw material form of forged metal that can be machined.
Binders: Another name for brakes.
Bite: The amount of grip the tires or car has with the track.
Black and Red Flags together: Indicates the end of a practice or qualifying session. All cars should exit the track and go to the pits or garage area. Checkered and red, or checkered and black, flag combinations may also be used.
Black Box: In car high tech electrical systems. These would control most engine functions. More technically referred to as the Engine Electronic Controls, the Engine Control Unit or the Engine Management System. May also include measure devices to record information during testing.
Black Flag: Report to the pits. Used to call in a car, either because the team is to be penalized, or because the car presents some sort of hazard that must be fixed (e.g., leaking oil, loose bodywork, or going too slow). Generally, the driver has a small number (2-3) of laps to obey the black flag, and a driver who continues after that point will be disqualified. At many tracks, an electric signboard next to the flagman's stand is used to display the number of the car being black-flagged, to avoid confusion.
Black Flag with White “X”: Signals a racer that is ignoring a black flag that if he/she does not come in they will cease scoring that car.
Black Slick: A condition describing a dirt tracks surface when it still has enough moisture to keep the material packed, but has hardened and is taking rubber.
Blade: Term that some drivers use for a rear spoiler. 
Bladder: Device that contains the fuel and keeps it from spilling and catching fire in the case of a rear impact.
Bleach Box: Section of track before the starting line where cars spin the tires in water. In early drag racing, actual chlorine bleach was used in place of water, originating the name.
Bleeder Valve: This is a device mounted in a wheel. It is a valve that is used to keep air pressure constant during a race. Air pressure increases with heat and this valve opens and releases air until the pressure returns to a preset amount.
Blend Line: Line painted on the track near the apron and extending from the pit road exit into the first turn. When leaving the pits, a driver must stay below it to safely "blend" back into traffic.
Blind Rally: A race in which the route is not released until just before the start.
Blip: A short tap on the throttle.
Blistered: Condition where a tire is run at excessive temperatures causing the tread to turn into a semi-liquid state. This is characterized by visible porosity in the tread, and sections of tread separating from the body.
Blower: Another name for a supercharger.
Block: An area of raised (or surrounded by grooves or sipes) tread on a tire.
Blocking: Racing term for changing position on the track to prevent drivers behind from passing. 
Blower Belt: The belt that drives the blower on a dragster. Also see Gilmer Belt.
Blow Over: A drag racing phenomenon where a dragster, most often a Top Fuel car, flips over itself. Excess traction and weight transfer lifts the front wheels, then air pressure under the nose pushes the front end higher until the car eventually topples over itself. Drag racing legend Don Garlits experienced the first "blow over".
Blown Engine: (1) An engine that has suffered a catastrophic bottom-end failure, such as a broken connecting rod. Engines that have blown usually have suffered irreparable block damage and have to be junked. Blowing an engine frequently produces a huge cloud of smoke and leaves oil and pieces of metal all over the track, making a caution flag necessary. (2) An engine equipped with a supercharger.
Blue Oval: Refers to a Ford. The name comes from the shape of its logo.
Blue with Yellow Stripe Flag: A signal to lapped cars to move out of the way of faster cars. The actual rules associated with this flag vary considerably. In some series, a driver can be penalized for ignoring this flag; in others, it is strictly an advisory (and in fact, the flagman might not bother). Often referred to as the "move over" flag.
Blueprinting: The meticulous matching to factory specifications all parts and/or components. Dressing parts to absolute design callout or manufacturer's specifications.
B-Main: A second-chance race sometimes seen at an event that uses heat races to determine qualifying and starting positions for the feature. The B-main includes all cars that failed to finish in a qualifying position in their respective heat races, and a certain number of additional qualifying positions are available to the B-main's top finishers. Also called a "last chance" or "B-heat" race.  
BMARA: Badger Midget Auto Racing Association.
Board Track: An oval track whose surface and foundation are made from wood. Elaborate board tracks were constructed in the 1910's and '20s, mainly on the West Coast, in part because good paving materials for earthen works tracks were not available (modern asphalt having not been invented yet). These tracks, built to lengths as long as a mile, were built for spectacle and often featured banking in the turns exceeding 45 degrees.
BOB: Battle of the Bluegrass Tour.
Bobble: A slight wiggle or a brief lose of control that is recovered by the driver.
Bolt-On Parts: Term used to describe the parts that attach to the car's chassis.
Bomber: A Stock car class where old cars (often retrieved from junkyards) are raced, with few or no modifications allowed. Intended to be the absolute lowest-cost way of going racing at many tracks, but they also have the side benefit of providing a measure of comic relief during a tense night of racing. Also referred to as "Jalopy", "Wrecker", "Thunder Car", "Detroit Iron" "Coyote" etc.
Boost: The amount of pressure generated by a turbocharger or supercharger as it forces the air/fuel mixture into a forced induction engine.
Bore: The diameter of an engine cylinder.
Bottom Dead Center: The position of the piston at the bottom of its stroke.
Bottom End: The reciprocating and rotating parts of an engine that transmit the engine's power, including the pistons, crankshaft, connecting rods, and main bearings. See also top end.
Bow Tie: (1) Chevrolet, from the shape of its logo. (2) A series of cylinder heads made by Chevrolet for racing, mainly for use by Late Models and drag racers.
Box: Slang term for a transmission.
B-Post: Post extending from the roofline to the base of window behind the driver's head.
Brain Bucket: Slang term for a helmet.
Brake Duct: A tube that takes air from the front or side of a car and directs it to the brakes in order to cool them.
Brain Fade: A lack of focus that can lead to making a mistake during a race.
Brake Balance: The difference in braking force between one end or side of the car, and the other. Racing brake systems are usually designed so that the front-rear brake balance can be adjusted, with more force going to one end or the other as desired to improve handling characteristics (side-to-side brake balance adjustment is less common, and not allowed in many series). Sometimes, this is done with a knob in the cockpit that the driver can use to change the balance while driving.
Brake Fade: Condition that occurs when the brakes get so hot they are ineffective and braking power is reduced.
Brake Tuning: Using both braking and steering ability of the car between the turn in point and the apex of a turn.
Breakout: (Run Under) In Drag racing, when your elapsed time is quicker than your dial-in, this causes you to be disqualified.
Break Loose: Describes when the tires are pushed beyond their threshold and they lose traction.
Brickyard: Nickname given to the legendary Indianapolis Motor Speedway, which although paved now, used to have a brick surface.
Buildup: Term use to describe an increase in tire pressure due to the tire heating up (by running and brake heating) and internal humidity turning into steam. To help limit pressure buildup teams use nitrogen dried air, or other gas to lower internal humidity.
Bull Ring: A general term for a short track usually a half-mile or less where local weekly races are held.
Bump Drafting: A drafting technique where a trailing car that is rapidly gaining on a preceding car will actually hit the preceding car in the rear (gently), in order to transfer some momentum to the preceding car and speed it up, which because of the dynamics of drafting, results in both cars gaining speed. A dangerous technique commonly used on superspeedways.
Bump Rubber or Bump Stop: A piece of rubber used to stop the travel of the suspension.
Bump Steer: Un-commanded steering motion in a front wheel, caused by the wheel's changing its toe angle as it moves up and down. Usually considered undesirable. Great effort is made to minimize the condition by changing the geometry between the steering rack and the suspension control arms.
Burn Off: Burning fuel during the course of a race. As fuel is burned, the car becomes lighter and its handling characteristics change, challenging the driver and crew to make adjustments to achieve balance.
Burned Piston: A type of engine failure, which is the result of pre-ignition or excessive heat in a cylinder, usually because the air-fuel mixture has become too lean for some reason. (Alcohol-fueled engines are especially vulnerable to this.) A burned piston has its top surface transformed into something resembling the surface of the moon, and may even have a hole burned all the way through it.
Burnout: Spinning of rear wheels at high RPM to heat and clean drive tire rubber prior to a run, resulting in increased traction.
Busch: The NASCAR Busch Series, previously known as the Busch Grand National. A Stock car series sanctioned by NASCAR. The cars are similar to Winston Cup cars, the main differences being smaller carburetors, less horsepower, and prohibitions on exotic materials.
Busch Whackers: Derogatory name for Nextel Cup teams or Drivers that enter in a Busch Series event.
Bye Run: In Drag racing, a lone run given to a randomly chosen car, because of an unequal number of cars in the round.
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C

Calendering: A machine process that combines body-ply rubber and cord fabric together into a specified thickness.
Calipers: A component of the braking system that houses the piston, which hydraulically pushes the brake pad against the rotor.
Camber: One of the three major front suspension geometry adjustments. The camber angle is the angle between the plane of the wheel (think of it as the plane of the hub face, or the brake rotor), and the vertical. Negative camber is when the top of the wheel is leaning toward the car. Positive camber is when the top of the tire is leaning away from the car. This adjustment setting is described in degrees.
Can-Am: Sanctions TQ Midget racing on asphalt oval tracks.
Cantilever: This is a tire designed to increase the tread width when rules restrict the rim width. The most noticeable characteristic is the pronounced sidewall extension. These tires typically present a challenge to the service technicians when mounting and dismounting.
Cap: A metal or plastic screw on cap for the valve stem.
Carbon Black: Ingredient used in the manufacturing of tires. Acts as a filler but also adds strength and color to a compound.
Carbon Monoxide: Colorless, odorless poison gas created by the combustion of carbon-based fuels. 
Carburetor: A device mounted on top of the intake manifold that controls the air-fuel mixture going to the engine.
Carcass: The tire body beneath the tread and sidewalls; also called casing.
CARS: (1) Championship Auto Racing Series. (2) Classic Auto Racing Series.
CART: Championship Auto Racing Teams, one of the two organizations that sanctions Indy car racing.
CASA: California Asphalt Sprint Association.
CASC: Canadian Automobile Sport Clubs.
CASCAR: Canadian Association for Stock Car Auto Racing. 
Casing: The tire body beneath the tread and sidewalls.
Caster: It's the angle between the front wheel kingpin and the vertical when viewed from the side. (Think of it as the "hinge" that the wheel swings on when the steering wheel is turned). All modern suspension designs have the top of the kingpin leaning toward the rear of the car. Higher angles can provide improved cornering traction, but a side effect is that such angles require extreme effort on the part of the driver to turn the steering wheel requiring power steering. The measurement is described in degrees, as in degrees of rotation. In a modern suspension design the "kingpin" is better described as the intersection of the upper and lower ball joints.
Catch Can: A small can that is used to catch fuel that comes out of the fuel cell vent when it overflows (while being filled). Also: Most fuel cells today have a check valve in the vent line that prevents fuel from backing out of the vent line. This valve also prevents air from escaping the cell, which would make it impossible to fill the cell, so the catch can has a protruding snout that is shoved into the vent line, and forces the check valve open so the car can be fueled. This applies mainly to Stockcars; Indy cars use a vent hose instead.
Catch Fence: The fence along the wall that protects spectators from errant cars, parts, etc.
Caution: A period when a race is stopped due to an accident or other dangerous situation (such as rain, debris, or spilled oil) on the track. Indicated by the display of a yellow flag and light. The cars may continue moving around the track behind a pace car and no passing is permitted. In most cases laps run under caution are counted and cars are permitted access to the pits for service.
Caution Lights: At most tracks, a series of signal lights around the perimeter of the track that duplicates the functions of some of the flags. Commonly, old traffic lights containing red, yellow, and green bulbs. Some use strobe or flashing yellow lights in addition to a solid yellow. 
C.C: Cubic Centimeter, a metric unit of volume measurement, equal to approximately 0.061 cubic inch.
CDCRA: California Dwarf Car Racing Association.
Center of Gravity: A measurement used in chassis setup to determine the overall balance of a race vehicle and adjust handling characteristics. The center of gravity is an imaginary point located in the car where if raised by that point, the car would balance perfectly. Center of gravity changes work inversely in dirt and asphalt applications. Raising the C.G. on an asphalt car will reduce traction while the same adjustment increases traction on a dirt vehicle. The opposite is true of lowering the C.G.
Center of Pressure: The point on an Indy car under-wing, which receives the greatest amount of airflow pressure. This measurement is critical to setting front to rear balance, especially on superspeedways.
C.F.M: Cubic Feet per Minute. A measure of airflow.
Chalk Mark: A measurement of the circumference written on the tire. This is usually not a cold circumference but a measurement taken after the tire has been removed from the mold and inflated. This measurement is used a reference point for comparing tire sizes.
Championship Cars or Champ Cars: (1) Refers to front-engine Indy cars that raced at Indianapolis and other Indy car venues until about 1965. See also Silver Crown. (2) The term that CART began using for its cars in 1998 (after it was barred from using "Indycar" as the result of a lawsuit by the IRL).
Chassis: The frame of a racecar that provides a mounting point for the motor, suspension, steering, roll cage, and drive train components.
Checked Out: Expression when the leader drives away from the rest of the field and will seem impossible to catch.
Check Up: To slow down abruptly, either because of a problem with the car, or because of an incident occurring ahead. When a driver checks up, he/she is supposed to hold up their right hand and wave it, as a signal to following cars, but there isn't always time. Sudden checking up is a frequent cause of "secondary accidents" that occur behind an accident or spin.
Checkered Flag (black and white): The race is over. This flag is always shown first to the winner; each car gets to complete the lap that it is on, and then the race ends.
Chicane: An "S" like track configuration generally designed on a fast portion of a track to slow cars. Also referred to as "esses" or a "switchback."
Chili Bowl: A nationally recognized indoor Midgets race in Tulsa, Oklahoma.
Christmas Tree: An electronic starting device used in drag racing that incorporates calibrated lights displaying a visual countdown for each driver, activated by a designated official. See full and pro tree.
Chrome Horn: Bumping into the rear of the car ahead of you, to cause him to get a bit loose (so he'll slow and you can pass him), or just to express dissatisfaction with his driving. The term comes from the early days of Stock car racing, when the racecars were showroom cars of the '40s and '50s with the huge, chromed bumpers that were in style then. The chrome horn is regarded as a dubious technique at best and downright dirty at worst.
Chromoly: Also Chrome Moly. Short for Chromium Molybdenum steel. Very strong and light tubing highly adaptable for racecars.
Chunking: Condition in which rubber comes off a tire in chunks due to the tire being chemically treated or a bad or misused compound.
Chute: (1) Short for parachute or drag chute. Used to assist high-speed braking. (2) A straight away on a track.
C.I.D.: Cubic Inch Displacement. A measure of volume, used to measure cylinder volume.
CIFCA: California Independent Funny Car Association. 
Circuit: Any racetrack. Also refers to the entire slate of races on a season schedule.
Circulating: Driving around a track with a damaged and/or slow car to accumulate laps and, more importantly, points and prize money.
Circular: A track with no straights. There have been such tracks in the past; the old Reading, Pennsylvania track was a well-known example in its day. There are no significant circular tracks existing today. (However, Flemington, New Jersey, is a rectangular track with straights so short that it is driven as a circular track.)
Circumference: The measured distance around the tread portion of a tire.
Claim Rule: A rule that allows parts from one competitors' car to be purchased by other competitors at a set price. Usually applied to engines, claim rules supposedly keep the cost of racing down by making it unprofitable to spend a lot of money on illegal or exotic modifications.
Clean Air: Air without turbulence created in the wake of other racecars. 
Clevor: Name for a Ford production-based small-block V-8, which is the basis for the current Ford NASCAR Winston Cup engine. The engine is an amalgam of the best features from the "Cleveland" and "Windsor" engines of the '70s, and the "Clevor" name is a combination of the two names. Ford is now phasing the engine out of production, and it's unclear how much longer it will continue to race in NASCAR.
Clip: On a tube-frame Stock car, the front and rear sections are designed so that if they are damaged in an accident, they can easily be cut off (with a cutting torch) from the main part of the chassis, and a new section welded on. These replaceable sections are referred to as the "front clip" and "rear clip".
Clipping: (1) Minor contact between racecars. (2) Refers to hitting precisely, or "clipping," the apex of a turn.
CLMA: Colorado Late Model Association.
Closed Wheel: A racecar where the suspension, wheels and tires are mostly covered by the body.
Clutch: The coupling device that when engaged or disengaged connects or disconnects the engine to the transmission.
Clutch Can: Bell housing, the bell-shaped housing used to encase clutch and flywheel.
Clutch Lockup: The progression of the clutch-disc engagement controlled by an air-timer management system.
CMT: Carolina Modified Tour.
CNYMS: Central New York Mini-Sprints.
Cock Pit: Area in a car where driver sits.
Cold Inflation Pressure: The amount of air pressure in a tire, measured in pounds per square inch (psi) before a tire has built up heat from driving.
Cold Pits: When there is no racing activity on the track and the pits are open to people other than team members and racing officials.
Collected: Getting hit by an out-of-control car while trying to pass by or through an accident in progress.
Combinations: A teams groups of engines, gearings, suspensions, aerodynamic parts, and wheel and tire settings that they forecast will work under varying conditions and tracks. These combinations (also known as set-ups) are recorded and used as baseline when teams arrive at a track.
Combustion: The burning of the fuel-air mixture in an engine cylinder.
Combustion Chamber: The part of the cylinder within an engine block where the fuel/air mixture is compressed by the piston and ignited by a spark from the spark plug.
Come In/Coming In: When a tire gets up to temperature and begins gripping. May also be called “fire”. Some rubber compounds will “come in” quicker than others.
Competition Area: The staging lanes and racetrack surface.
Competition Yellow: A scheduled caution period during a race. It has the effect of drawing all the cars together, which can prevent the race from becoming a "runaway"; it also de-emphasizes the importance of pit stops by decreasing the number of pit stops that must be made under the green flag. Commonly used by ASA to reduce costs by making fast pit stops less important. See also halftime.
Compound: This refers to the mixture or durability of the rubber on the tread of the tire. Compounds are usually described as "hard" or "soft". The more abrasive the track is the harder the compound you would want to use.
Compression Ratio: The volume of the combustion chamber and cylinder when the piston is at the bottom of its stroke, divided by the volume of the combustion chamber and cylinder when the piston is at the top of its stroke. Higher compression ratios tend to increase engine efficiency.
Compressor: A machine that pressurizes and regulates airflow for delivery into tools or tires.
Connecting Rod: A metal rod used to connect the piston to the crankshaft.
Consolation Race: Sometimes called the "consy," this is a race for teams who fail to qualify for a feature race or main event. (Some people incorrectly use this term to refer to a B-main.) The consolation typically will come with a small amount of prize money for the top few finishers, or the promoter might offer to cover the day's expenses of the consy winner. The purpose of the consolation race is to encourage the teams that failed to qualify to come back and try again at the promoter's next event. See also back gate.
Constant Radius Corner: A turn that has the same radius throughout the turn.
Contact Patch: The area of a tire that is in contact with the ground.
Contingency Awards: Money or prizes that are awarded to race participants by parties other than the race promoter. The contingency award may be based on performance, on a team's use of a sponsor's product, or any other criteria that the party sponsoring the award feels like imposing. Some contingency awards require that the racecar carry a sponsor's decal.
Cool Down Lap: A lap run after taking the checkered flag in order to slow down before leaving the track.
Co-opertition: Slang term that combines the two words Cooperation and Competition. Describes the act of teams cooperating during competition. The best example is drafting at superspeedways to benefit both cars.
Cord: The strands of material forming the plies or layers of the tire. Cords may be made from fiberglass, rayon, nylon, polyester, steel or other materials.
Core: The mechanism in a tire valve stem that allows one-way passage of air. Also called "valve core".
Cornering Force: The sideways force or lateral gravitational (G’s) forces exerted on a car and driver while going through turns at speed.
Corner Worker: Racetrack or series safety staff that are located in the corners to notify drivers of any dangerous situations in the area.
Cosmetic Damage: A spot or location of damage that is not a structural problem to the operation of the tire.
Cowl: A removable metal scoop at the base of the windshield and rear of the hood that directs air into the air box.
Cowl Induction: Housing for the air cleaner that connects the air intake at the base of the windshield to the carburetor.
C-Post: The post extending from the roofline of a racecar to the base of the rear window to the top of the deck lid.
Crankcase: The area of the engine block that houses the crankshaft.
Crankshaft: The rotating shaft within the engine that delivers the power from the pistons to the flywheel, and from there to the transmission.
Crash: An incident where one or more cars are involved in a wreck.
Crash Clause: A special provision that is included in a racecar rental contract regarding the amount that the renter will pay the owner if the racecar is wrecked.
Crate Motor: In some series such as ASA, a similar motor is supplied to all competitors. This is mainly done to reduce costs and even the competition, similar to a specified tire rule.
Crew Chief: The individual responsible for all mechanical aspects of the racecar and strategic decisions during pit stops and the race.
Cross Weight: The percentage of weight on the right front vs. the left rear wheel.
Crossed Flags: (two flags furled and crossed in an X shape): Indicates that half of the distance of the race has been completed. Usually, in oval-track racing, the rules stipulate that once one-half of the scheduled distance has been completed, if some condition (such as weather) makes it impossible to continue, the race will be called and the current running order becomes the final result. The crossed flags are a signal that this point in the race has been reached. Also, there is sometimes a bonus award for being the leader of the race at the crossed flags.
Cross Thread: Stripping of the wheel stud threads when crewmembers hurriedly refasten lug nuts.
Crush Panel: On a tube-frame Stock car, a sheet metal panel that fills in the gaps between the firewall and the side body panels. If the crush panel gets damaged, engine heat (and frequently exhaust gas) comes into the cockpit, which can make the driver extremely ill.
CTS: Craftsman Truck Series.
Cure: The process of putting a completely assembled green tire in a press and forming into a finished tire.
Cushion: Area of the corner above the farthest outside groove on a dirt track where loose dirt builds up.
Cut: A sharp turn or a racecars ability to negotiate a turn. The car is cutting well means the car is able to turn well.
CVM: Canadian Vintage Modifieds.
CVSCRA: Carolina Vintage Stock Car Racing Association.  
Cylinder: A chamber in the engine in which combustion occurs and drives the piston.
Cylinder Head: The top or lid over the cylinder(s).
Cylinder Liner: A circular housing that the piston moves in when the cylinder is not an integral part of the engine block. Also referred to as a “sleeve”.
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D

DAARA: Daytona Antique Auto Racing Association.
Damper: Device used to restrict the travel of a part usually a spring.
Darlington Stripe: A streak of scraped-off paint that appears on the right side of a car, from having made light contact with the outside wall. The term originated at Darlington back in the '60s, when the track had Armco for its retaining walls.
Dash: An event that is usually six to eight laps in length. Starting lineup of this event is usually determined by combination of Qualifying and Heat Race results. The finishing order of this event usually determines starting order of the first three or four rows of the Feature event.
Date TIN: The alphanumeric mark located above the tire bead on the reverse sidewall. The actual "Date" portion of the TIN is only visible on DOT type tires.
Dead Pedal: A footrest found to the left of the operating pedals to give the driver a place to put his left foot during hard cornering.
De-Beading: This is when a tire dismounts from a rim. This is normally caused from low air pressure.
Decals: A tradition as old as Stock car racing itself. Decals are a low-budget form of advertising that sometimes provides rewards that are small, yet important to struggling teams. Contingency awards are sometimes tied to the display of decals.
Deck Lid: The trunk lid. On most Stock cars, the trunk is vestigial, but the lid remains for access to the fuel cell, oil tank, battery, and other things that might be stashed away in that space.
Decreasing Radius Corner: A turn that has a smaller radius during the last half of the corner.
Deep Staging: In drag racing, when the racer inches his car forward, not completely passed the starting line (staging line) so much as to turn off the pre-stage light. This technique is often used to break the concentration of your opponent at the line. Deep staging increases E.T. but lowers your reaction time.
Defect: A general description of a manufacturing flaw. This could be cosmetic or structural in nature.
Delamination: Visible circumferential lines that occur when spiral tread wraps open up. This condition is usually cosmetic but in extreme conditions can be a performance problem.
Depth Holes: Cavities located in the tread surface that enables wear measurements.
Detroit Locker: A brand name of a ratcheting (limited slip) rear end commonly used in Winston Cup.
Dialed In: When a cars setup is in an ideal state.
Dialing In: The driver and crew making setup adjustments to for better handling. 
Dialing Under: Allows competitors in Stock and Super Stock the option of selecting a time faster than the National Index. Applied in handicap elimination racing where breakout is in effect.
Dial-ins: Driver's predictions of E.T.'s their cars will run in their first eliminations.
Diameter: The height of the tire (usually unloaded). 
Diamonding: Taking corners by driving into the corner fairly straight, making a sharp turn in the middle of the corner, and then driving out fairly straight (such that, as the car goes through the corner, it moves from the inside to the outside and then back to the inside). On an oval, this causes the car to describe a diamond-shaped trajectory around the track, hence the term. This is, in a way, the opposite of the standard technique for taking a corner, and often results in slower lap times, but it may produce faster times from a car that is severely pushing, or on a very slick track.
Diaper: A blanket made from ballistic and absorbent material, often Kevlar, which surrounds the oil pan and serves as a containment device during engine explosions. Also used to prevent fluid leaks from damaging racing surface during indoor racing events.
Dicing: Close, exciting driving between 2 or more racers. Positions are exchanged frequently.  
Direct Drive: When a drive train is directly connected between the engine/crankshaft and the axle without a clutch.
Directional: Usually refers to a tire that is only to be run one way and not reversed. Indicated by directional arrows. This is due to the construction of the tire. Running a directional tire the wrong way can result in its destruction.
Dirt Track: A track, which is not paved, but rather has a dirt (usually red clay, or some mixture including clay) surface. Dirt tracks host mainly Late Model, Midget, and Modified classes in weekly racing and some touring series. Dirt tracks are nearly always short tracks; most range from 1/8 to 1/2 mile.
Dirty Air: An aerodynamic term for turbulent air currents caused by fast-moving cars. Can cause a trailing car to lose control.
Dismount: Removing a tire from a wheel.
Displacement: In an engine, the total volume of air/fuel mixture an engine is theoretically capable of drawing into all cylinders during one operating cycle. Described in cubic inches or cubic centimeters.
Disqualification: The most severe during-race punishment that a sanctioning body can impose. Disqualification is imposed only for the most severe infractions, such as ignoring a black flag or deliberately wrecking another car. It may also be imposed after the fact for severe technical violations, which may not be discovered until after the race, such as having an engine that is too large or carrying illegal equipment. Note that disqualification does not necessarily mean that the disqualified car finishes last; usually for a during-race infraction the scoring simply stops counting that car's laps at the time that the infraction is committed. A disqualification will nearly always bring about some other penalty, such as a monetary fine, a point's fine, probation, or suspension.
Dive: The amount the front end of the car lowers during deceleration or braking. Usually before entering a turn.
DNF: Acronym for "did not finish". The opposite of running at finish. Most racing box scores will list, for each car, either "running" or a very brief reason why the car DNF'ed, such as "engine" or "accident".
DNQ: Acronym for "did not qualify".
DNS: Acronym for "did not start". See also alternate starter.
DOHC: Dual Overhead Cam. Engine with two camshafts over a bank of cylinders; generally one cam operates the intake valves, and the other the exhaust valves.
Door Bars: Term used to describe the side protection bars built into most full-bodied racecar roll cages. Often, 3 or 4 horizontal bars are joined to the front and rear upright support bars to form the door bar structure.
Door Car: As the name implies, any drag racing vehicle with functioning doors. Although they resemble passenger vehicles, Funny Cars are not door cars, as their doors do not function.
Dope: (1) Slang term for the homebrew fuel mixtures that were used in Indy car racing in the '20s and '30s. In the days when available gasoline was very low in octane, teams often mixed their own gas so that they could run higher compression ratios. (2) Refers to the practice of treating tires with chemicals to alter their thermal and traction capabilities. Practice is illegal and dangerous.
DOT: Department of Transportation. Governing body that establishes regulations including tire labeling and performance standards of tires that are run inside the United States on public roads and highways.
DOT Markings: A code molded into the sidewall of a tire signifying that the tire complies with U.S. Department of Transportation motor vehicle safety standards. The DOT code includes an alphanumeric designator, which can also identify the tire's manufacturer, production plant, and date of production and brand.
DOT Tires: Used to refer to street-legal tires that can be purchased by the public, as opposed to racing tires. Many lower-cost forms of racing require use of Department of Transportation (DOT) tires.
Double: Recent term for competing in the Indianapolis 500, and the Coca-Cola World 600 at Charlotte, in the same day ("running the double").
Doughnut/Donut: (1) Circular patterns that are formed on the side of a car when it comes into contact with the front or rear fenders of another car, and that car's tires (perhaps slightly protruding from the fenders) rub off the paint, forming a circular rub pattern. (2) Spinning a vehicle around and around by over-accelerating and turning at the same time, leaving rubber on the track in a circular or donut shape. (3) An extra piece of rubber inserted into a spring.
D-oval: Type of oval track that has a gradually, continuously curving front "straight". Michigan, Fontana, and Richmond are examples.
Downforce: Refers specifically to downward forces generated by aerodynamics, either due to the car's body shape or due to aerodynamic aids such as spoilers and wings (as opposed to downward force resulting from the car's weight or from G-forces). Downforce resulting from aerodynamics greatly increases the traction ability of the tires, but it also increases wind resistance, which is the trade-off for the increased traction.
Downshift: Moving the transmission to a lower gear.
Drafting: An aerodynamic phenomenon that occurs at high-speed tracks. A car following another car runs in a partial vacuum left behind the lead car, which means that it doesn't have to use as much power moving air aside. The lead car also benefits, because the following car is occupying the space where the air would otherwise be trying to flow back in and creating drag. Two cars in a draft can go faster than either of the cars could go by themselves.
Drag: The resistance a car experiences when passing through air at high speeds.
Drag Coefficient: A measured amount of how much drag an object creates while traveling through the air.
Drag Slot: When the starting grid for a race contains an odd number of cars (and assuming that the cars are started two-abreast, which is usually the case in Stock car racing), the last car in the field starts on a row by itself. That car is said to be in the drag slot.
Drift: A controlled slide through a turn or in an open area. Drifting has become a competitive sport.
Drive Line: All parts included in the drive train not including the engine and the transmission.
Drive Plate: A splined metal plate that transmits the rotation of the axle shaft to the hub assembly on solid axle suspensions. Variations of this design allows for 2-3 degrees of camber in the system.
Driver's Meeting: A meeting which usually takes place 10-30 minutes prior to a major race, conducted by race officials, and which all drivers in the race are required to attend. Often, the meeting is merely a formality, but sometimes it is used to discuss unusual conditions, pass on last-minute rules changes, or work out issues between drivers.
Drive Shaft: The shaft mounted between the transmission and the rear end differential.
Drive Shaft Strap: A U-shaped strap that is fastened to the bottom of the car, and passes beneath the drive shaft. Its purpose is to keep the drive shaft in the car if the shaft or one of its U-joints breaks. Use of drive shaft straps is mandatory by most oval track racing divisions. Sometimes referred to as a "Drive shaft hoop".
Drive Train: All parts that supply power to the wheels including the engine, transmission, drive shaft, differential, and hubs.
Driving Away: When a driver is pulling away from the field with little challenge from anyone else in the race.
Droop Limiter: A device that controls downward suspension travel.
Dropping a Cylinder: A generic term for any condition that causes an engine cylinder to stop producing power. In racing engines, this usually results from either an ignition failure, or from a valve failing to open or close properly. (The latter often results in the valve contacting the top of the piston, leading to engine failure.)
Drop the Hammer: When a driver puts the gas pedal to the floor.
Dry Hops: Process of spinning your tires on dry pavement creating off and on contact with the ground.
Dry Line: A clear or dry line on the track that develops after rain because of more frequent use.
Dry Sump: The type of oiling system used on most racing engines. In a dry sump system, oil that isn't being used at the moment is stored in a tank, away from the engine, eliminating the need for the "deep end" on the oil pan. 
Dry-Break Connector: A connector used for fueling apparatus (gas cans or hoses) that can be connected or disconnected under pressure without spilling any fuel.
Dry-Slick: A dry dirt track with little or no moisture or grip. Often associated with a dusty track.
Dry Weight: A car's weight without any liquids such as gas and oil.
Dump Shifting: Skipping gears while downshifting.
Durometer: A device used to measure the hardness of the rubber on the surface of a tire.
Dwarf Car: A racing car, with a vintage-replica body (usually of a car from the '30s or '40s) built on a tube-frame chassis, and usually with some type of 4-cylinder engine. Many dwarf-car divisions are spec series, with all competitors being required to purchase the cars from a specific builder, and with very few or no mods allowed. See also Legends.
Dynamic: Dimensions or descriptions that apply when an object (tire, suspension or car) is in use or in motion. (See "static")
Dynamic Weight Transfer: The transferring of weight from side to side during cornering, from rear to front during deceleration and from front to rear during acceleration.
Dyno: Short for dynamometer. A device used to measure the power output of an engine, in or out of a car, by applying its power to a load. The load is usually some form of brake or friction device (such as a water turbine). The term is often used loosely for any kind of test stand where engines are run out-of-car, whether under load or not. Recently, some people have also began using the term to refer to any piece of testing gear that tests the dynamic performance of a racing component, such as the "shock dyno".
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E

Early Apex: When a driver turns into a corner too soon.
Economy Run: When a driver drives conservatively to save the engine, fuel and tires.
EEC: Electronic Engine Control.
EGT: The Exhaust Gas Temperature. 
EIRI: Except in rare incidents.
EKRL: Endurance Kart Racing League.
Elapsed Time (ET): The total time it takes to get from the starting line to the finish line. Each car must have its number on the side of the car, in the door area, and on the roof. Small numbers can appear on the nose, in the place where the headlights would be on a production car.
Electric Eye: A generic term for any electronic timing device.
Electrical: Sometimes used as an excuse for a car's retirement from a race when revealing the real reason would be embarrassing; for instance, if the engine fails in a race being sponsored by the engine's manufacturer. This type of prevarication isn't very common, fortunately, but it does happen. The reason why "electrical" is often used in these situations comes from an apocryphal story: a team, which had suffered a pyrotechnic engine failure, gave their reason out as "electrical." When an incredulous series official queried, he was told, "a rod that went through the block knocked the alternator out, so it was an electrical problem."
Eliminations: When cars are raced two at a time, resulting in one winner and one loser "eliminated." Winner continues to race in a tournament-style competition.
End Plate: The vertical end portion of a wing.
Enduro: A short-track event, which runs at a longer-than-usual distance and with an abnormally large field. In an enduro, the lead cars start to enter lapped traffic after only a few laps. This makes the event more of a challenge to the driver to be smooth and stay out of trouble, rather than a speed and horsepower contest.
Engine Computer: A microprocessor that controls the functions of the engine, such as fuel delivery and engine timing. Almost universal in passenger car engines since about 1985, and Indy car engines have been using them since the late '70s. However, computer-controlled engines are still not permitted in NASCAR.
Engine Leasing: Process where a race team leases an engine from an engine builder for a specific length of time for a fee. All maintenance, rebuilds, and tuning are handled by the leasing company. Leases usually occur when teams do not have their own engine shop or when their product is inferior to other producers.
Entry: The line or point a vehicle enters into a turn.
Entry Level: A class of racing with a wide range of rules and types of cars that include Street, Pure, Hobby, Super, Factory, Pony, Mini, and Limited Stocks as well as Bombers, Road Hoggs, Thunder Cars, Cruisers, Roadrunners, some Sportsmen, Runabouts, Chargers, Figure 8's and many others.
EOQM: Eastern Outlaw Quarter Midgets. 
ERA: Englewood Supermodified Association.
ESDCA: Empire State Dwarf Car Association.
ESS: Empire Super Sprints 
Esses: An "S" like track configuration generally designed on a fast portion of a track to slow cars.
E.T.: (Elapsed Time). The total time it takes to get from the starting line to the finish line. Each car must have its number on the side of the car, in the door area, and on the roof. Small numbers can appear on the nose, in the place where the headlights would be on a production car.
Equalize: To gradually lose pressure in an inner-liner equipped tire, until the main carcass pressure equals the inner liner pressure. When this happens, the inner liner partially unfolds inside the tire and flops around, which can create a severe vibration.
Equal Loading: When two tires on the same axle have the same amount of weight applied or loaded.
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F

F1: Abbreviation for Formula One.
F.I.A: International Federation of Automobile Clubs. Sole international body governing motor sports outside the United States.
Fabricator: Team member responsible for the body of the racecar.
Factory Team: A team owned, operated, or sponsored directly by an automobile manufacturer.
Fall Off: Gradual or drastic deterioration of a tires performance during use.
FASCAR: Florida Association of Stock Car Auto Racing.
Feature: The main event at a weekly-racing session or regional (or, less commonly, a national) event. Typically, a short track running weekly racing will have several classes, and each class has a feature (possibly more than one) where most of the money and points for that class are awarded. Starting positions for the feature are often determined by running heat races.
Fence: Term to describe the barrier on the inside or outside of the tracks racing surface. I may be a wall or steel rail but still be referred to as a fence.
Ferrous: Containing iron, as in metals.
Fidgets: Slang for the Ford Focus Midgets.
Field: The group of cars that starts a race or the total number of cars in attendance. May also refer to the group of drivers and teams that competes regularly in a particular racing series.
Field Filler: Cars that enter an event to fill out the field of entrants. This is done in order for the series or promoter to present the advertised car count and the teams to get a guaranteed start and finishing position pay. These cars may start the race, complete a few laps, and then park.
Figure-8 Racing: Races run on a figure-8 shaped track. This is done by paving two lanes in an X shape through the infield of a conventional oval.  In a Figure-8 race, there is an intersection in the middle of the track, which the cars must navigate to avoid wrecks with crossing traffic.
Fill the Mirrors: When a driver is pressuring another driver so feverishly that the rear-view mirror is filled their pursuer.
Finish Line: Line, which determines winner and computes Elapsed Time.
Fire: When a tire gets up to temperature and begins gripping. May also be called “coming in”. Some rubber compounds will “fire” quicker than others.
Fire Bottle: A brand name for a model of fire extinguisher designed to be used in a racecar; sometimes used to refer to a fire extinguisher in general.
Fire Suit: The suit worn by the driver (or others potentially exposed to fire, such as a gas man), consisting of several layers of a fire and heat-resistant fabric such as Nomex or Kevlar. The development of fire suits in the late '60s cut down greatly on burn injuries suffered by drivers.
Fire Wall: A solid metal plate that separates the engine compartment from the driver's compartment of a racecar.
Fishtail: Aft lateral oscillation of a vehicle, generally the result of traction loss.
Flagman: Person who uses flags to signal various conditions to the drivers and teams. At weekly-racing events, the flagman is often the person who has the final say over the starting and stopping of the race, and handing out penalties to drivers who commit infractions. (In professional series, a race director generally has that responsibility.) Generally, the flagman stands on a platform that is elevated over the outside edge of the track, at the start/finish line. (In old films, one can see the flagman standing on the track, but that is rarely done now due to the obvious safety concern.) Also referred to as the starter.
Flags: Used by the flagman to signal various conditions to the drivers and teams. At most tracks, a series of signal lights around the perimeter of the track duplicates the functions of some of the flags.

• Black: A flag demanding a car and driver report to the pits either because the team is to be penalized, or because the car presents some sort of hazard that must be fixed. A driver who continues after that point will be disqualified. At many tracks, an electric signboard next to the flagman's stand is used to display the number of the car being black-flagged, to avoid confusion.
• Black and Red together: Flags indicating the end of a practice or qualifying session. All cars should exit the track and go to the pits or garage area. 
• Black with a White “X”: Signals a racer that is ignoring a black flag that if he/she does not come in they will cease scoring that car.
• Blue with Yellow stripe: A signal to lapped cars to move out of the way of faster cars. The actual rules associated with this flag vary considerably. In some series, a driver can be penalized for ignoring this flag; in others, it is strictly an advisory (and in fact, the flagman might not bother).
• Checkered (Black and White): The race is over. This flag is always shown first to the winner; each car gets to complete the lap that it is on, and then the race ends.
• Crossed flags: (two flags furled and crossed in an X shape): Indicates that half of the distance of the race has been completed. Usually, in oval-track racing, the rules stipulate that once one-half of the scheduled distance has been completed, if some condition (such as weather) makes it impossible to continue, the race will be called and the current running order becomes the final result. The crossed flags are a signal that this point in the race has been reached. Also, there is sometimes a bonus award for being the leader of the race at the crossed flags.
• Green and Yellow together: Used to indicate the start of a race, when it is necessary to start the race under caution. This might occur, for example, if it has rained before race time, the track is still damp, and the race needs to start by a certain time in order to meet television commitments.
• Green: Start racing, or resumes racing. The green flag is waved at the start of the race, and at the end of every caution period; it remains out until the next caution period, or the end of the race.
• Red: Race halted; all cars must drive slowly around to the start-finish line (or some other point designated by the officials) and then stop. Used when the track is blocked, or needs repair, or to signal a scheduled break in the race or when weather conditions make it unsafe to continue even at caution speed.
• Red with Yellow "X": Used by NASCAR to indicate that the pits are closed (in all of the NASCAR professional series, when a caution occurs, the pits are closed until the pace car has entered the track and the field is formed up behind it). An official positioned at the pit entrance holds this flag. Any car that passes this flag and enters the pits is subject to a penalty. Some other series use a similar flag to indicate that there is an emergency vehicle on the track.
• White: One more lap remains in the race. In NASCAR, a car may not pit or receive any form of assistance (for instance, a push from another car) after taking the white flag.
• Yellow: Caution period indicates that a wreck has occurred, or some other condition.

Flash Shield: A device to encompass the air inlet of a carburetor's sides, top, rear. To protect driver in case of engine backfire.
Flat: Description of a tire assembly that won't retain pressure.
Flat Out: To run a racecar at maximum speed.
Flat Spot: A portion of a tire worn down excessively due to locking the brakes or spinning the car.
Flip Ups: An aerodynamic device located in front of the rear wheels to direct airflow over the back tires.
Flopper: Slang term in drag racing to describe the Funny Car class. Derived from the fact that modern funny cars use a fiberglass body that "flops" down over the chassis.
Fly by Wire: A term, borrowed from aviation, to describe a control system where the driver, instead of directly controlling something through mechanical linkage, controls it indirectly through electrical actuators. In particular, refers to cars in which the steering, transmission, throttle, or braking is controlled in this matter.
Flywheel: A heavy metal rotating wheel that is part of the race car's clutch system, used to keep the crankshaft turning smoothly.
FMSA: Florida Mini-Sprint Association.
Footprint: The portion or amount of area of the tread that contacts the road.
Force Variation: A process to measure differences in tire/wheel consistency. Determines the highest portion of the tread in order to match it up to the lowest portion of the wheel for best performance and minimize tire/wheel assembly vibration.
Formula One: An open wheel series similar to Indy cars but with more sophisticated computer controls, higher rpm engines, and mostly run on road courses. Considered to be the highest form of motor sports.
Forward Bite: A general term used to describe the amount of force available to move the car forward. In setup, putting more forward bite in usually refers to adding more traction to the rear of the car.
Foul Start: Leaving the stage beam at the starting line before the green bulb illuminates resulting in immediate disqualification. Red lights at the bottom of the Christmas Tree signify a foul start.
Four-Barrel: The type of carburetor used in many types of racing.
Four-Link Suspension: Commonly used racing suspension. Found in all forms of racing, four link is characterized by four individual bars, two on each side of the rear end, used to control rear end movement and traction.
Four-Point, Five-Point: See harness.
Fours: Four-car-wide salute to the fans from the racers. Normally at the start of the night’s main event.
FPRS: Formula Pro Racing Series.
Frame: The main structure or chassis of the car.
Frame Rails: Main lengthwise component beams of the chassis or frame.
Free: The same as loose. A handling condition (known as "over-steer" to road racers) where, when the car goes through a corner, the rear end of the car wants to slide towards the outside of the turn. If the car gets loose enough, it will spin out. Adjustments can be made to “free up the car”.
Freight Train: A group of drafting cars lined up like a train.
Fresh Rubber: New tires.
Friction: Contact between two surfaces. Usually results in heat.
Front Clip: Beginning at the firewall, the front most section of a racecar.
Front Steer: An arrangement of the steering gear where the tie rods connect to the wheel hub at a point forward of the kingpin.  
Front Stretch: Main straightaway between turns 4 and 1 on an oval track.
FSCDRS: Fastest Street Car Drag Racing Series.
Fuel: Flammable liquid used to power internal-combustion engines.
Fuel Cell: A type of fuel tank that has a rubber (or similar) inner lining, to contain the fuel if the outer tank is punctured. Most also contain a foam or metal-mesh filling, which prevents fuel sloshing and keeps the flame out of the tank if a fire occurs.
Fuel Check: An area of technical inspection in which fuel is tested for compliance.
Fuel Injection: (F.I.) A system replacing conventional carburetion, which delivers fuel under pressure directly into the combustion chamber.
Fuel Pump: A device that pumps fuel from the fuel cell through the fuel line into the carburetor.
Fuel Stint: The amount of laps or time run on a full tank of fuel.
Full Bore: Running as fast as possible.
Full-Face: A helmet that covers the entire face and head. When used with a head sock, it provides full-uninterrupted coverage of the driver's upper body against fire, and the enclosure of the mouth prevents the driver from inhaling the flame during a fire. It also provides protection to the forehead and eyes, and makes separate goggles unnecessary.
Full Floater: A type of rear axle where the axle housing extends all the way out to the wheels, and the wheels are held on bearings fastened to the ends of the housing tubes. Works in conjunction with drive plates.
Full Tree: The method used to start cars at the starting line. The method used is one yellow light is used at a time, then the green light. As opposed to all yellow lights are lit at once then the green light (Pro-Tree). The reaction time used in full tree is .500.
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G

G’s: Gravitational forces exerted on a car and driver under acceleration, braking, and cornering.
Garage Area: A covered or enclosed area, usually in the infield of an oval track, where the racecars are stored and worked in when not on the track. The garage area is the place for performing repairs that are more extensive than possible in the pits. The garage area is protected from the "hot" area of the racetrack, and no fast driving is allowed there. Indy car and road racers sometimes refer to the "paddock" area.
GARRA: (Grand Am) Grand American Road Racing Association. Sanctions Sports Car racing events in the US and Canada.
Gas: Used to mean gasoline (as opposed to alcohol or other fuels). This usage appears more commonly in drag racing, where a division with the word "Gas" in its name means those cars in that division must run on gasoline, but it is also used some in oval track racing.
Gas Catcher: Pit crewmember that is responsible for the catch can. This person may also perform other duties during a pit stop.
Gasket: A thin material, made of paper, metal, silicone, or other synthetic materials, used as a seal between two similar machined metal surfaces such as cylinder heads and the engine block.
Gasman: The member of the pit crew who refuels the car. In stock car racing this person must lift heavy cans of racing gasoline (Usually 22 gallons weighing about 87 lbs. or 40 kg) up to the car's filler inlet. In Indy car racing, this person handles a large hose with a huge stainless-steel connector at the end, which delivers fuel from a tank on a stand behind the pit wall.
Gasoline: see gas
Gasoline Alley: The garage area at Indianapolis Motor Speedway.
Gasser: A dragster or any car that runs on gas.
Gather/Gathered It Up: Regaining control of a racecar after becoming loose or spinning.
Gathered Up: A car becoming involved in a wreck not his/her fault. Being “gathered up” by another car.
Gauge: An instrument, usually mounted on the dashboard, used to monitor engine conditions such as fuel pressure, oil pressure and temperature, water pressure and temperature, and RPM (revolutions per minute).
GCS: Golden State Challenge.
Gearbox: Racing term for a transmission.
Gear Ratio: The ratio of engine RPM’s to rear wheel RPM’s.
Gears: Circular, wheel-shaped parts with teeth along the edges. The interlocking of two of these mechanisms enables one to turn the other.
Gearset: Two or more gears used to transmit power.
Gilmer Belt: Toothed or splined drive belt used with matching pulley, generally a non-slip drive belt.  The large belt used to transfer power from the engine's crankshaft to the input shaft of a supercharger. Most are reinforced and molded to match the teeth of the drive gear.
Give Up: Gradual or drastic deterioration of a tires performance during use.
Glass Transition Point: The temperature that the tread rubber will freeze and crack. This temperature will vary depending on the rubber compound.
GLOSS: Great Lakes Outlaw Sprint Car Series. 
Going up through the Gears: Refers to a driver up-shifting from the lowest to the highest gear.
Gold Crown: The name that USAC used for its Indy car series between about 1970 and 1980. Prior to about 1970 there were few paved-track Indy car races; many races which were part of the "National Championship Trail" (which traces its lineage back to the AAA days) were held on dirt, using cars called Champ cars built for the purpose. By 1970, the Champ cars and the rear-engine Indy cars had diverged wildly, and so USAC decided to separate the dirt track races and form a separate series for them which was named the Silver Crown series.
Got Under: When a car out brakes another going into a turn and passes on the inside.
Graining: A pattern of nearly parallel ridges on a tires tread. Cause by over aggressive driving on a tire that has a compound that is usually too soft or has not been allowed to be brought up to a good operating temperature.
Grand Am: Grand American Road Racing Association. Sanctions Sports Car racing events in the US and Canada.
Grand Marshal: An honorarium, usually reserved for sponsors and celebrities. Feature races often have a grand marshal, whose most visible function is doing the traditional "Gentlemen, start your engines" bit at the beginning of the race.
Grand National: The original name for what is now known as the NASCAR Winston Cup series. The Grand National name was adopted in the early '50s, and persisted until 1971 when the series named was changed to Winston Cup, after its title sponsor. To make things confusing for historians, when the old Late Model Sportsmen series was re-formed into a touring series in 1982, it was given the name Busch Grand National. The Winston Cup name is now used generally to refer to the NASCAR top series, both before and after 1971.
Grand National East: This was a series created by NASCAR in 1972. It consisted of all of the dirt-track races which were removed from the Winston Cup series that year, both to reduce the number of races on the WC schedule and because the dirt races were considered old-fashioned and too stereotypically Southern. (Consequently, this year is generally considered to be the beginning of what is now called the "modern era" of NASCAR racing.) Without the Winston Cup stars, the Grand National East series races drew poorly, and the series died out after two years.
Grand National West: At the time that NASCAR created the Late Model Sportsmen championship for local and regional racers in the South and East in 1948, it recognized that it would be impractical for teams on the West Coast to tow their cars to the other side of the country to participate. Because NASCAR wished to maintain its ties with the West Coast hot rodders, it created a similar but separate series called the Pacific Coast Late Model series. In 1972, when the Grand National East series was created, the PCLM series was renamed Grand National West to be analogous with Grand National East, even though the two series were nothing alike in the cars, the racing, or the participants. Unlike the ill-fated East series, the West series survives today and a vestige of the name change can be seen in its current name, Winston West.
Grand Prix: This French term meaning grand prize is widely used to refer to a race. At one time in racing, it was used exclusively for a series' grand finale, usually the most important race.
Gray: Area on a paved track where nobody runs, particular in the corners. Sometimes it actually is visibly a lighter color than the groove. The gray area is often full of marbles and other loose material that causes a severe loss of traction for any car that goes there.
Green: (1) The state of the track when a green flag is in effect; the opposite of a caution period. (2) A track which is either newly paved, or has experienced heavy rain since the last time the track was raced on, or just hasn't been used in a while. A "green" track lacks the accumulation of tire rubber that builds up when the track is raced on, which changes the handling characteristics of cars that race on the track.
Green and Yellow Flags together: Used to indicate the start of a race, when it is necessary to start the race under caution. This might occur, for example, if it has rained before race time, the track is still damp, and the race needs to start by a certain time in order to meet television commitments.
Green Flag: Start racing, or resumes racing. The green flag is waved at the start of the race, and at the end of every caution period; it remains out until the next caution period, or the end of the race.
Greenhouse: The area inside the racecar, generally referring to the top inside part of the racecar, where the driver sits.  The greenhouse area is basically from the windshield to the back deck lid, and from the doorframes up.
Green Tire: A completely assembled tire that has not yet been cured. Also refers to an environmentally friendly tire that uses less oil.
Green Track: A track which is either newly paved, or has experienced heavy rain since the last time the track was raced on, or just hasn't been used in a while. A "green" track lacks the accumulation of tire rubber that builds up when the track is raced on, which changes the handling characteristics of cars that race on the track.
Green/White/Checkered: When a caution occurs near the end of a race, the series officials may choose to go passed the advertised race length to get the race in under green. They may finish the caution and then go green for one lap, followed by the white flag indicting one lap to go, and then finish with a checkered flag. Basically a 2-lap finish under green instead of finishing a race under a caution.
Grenade: An engine built to go very fast for a few laps, for qualifying. Grenade engines are usually built with lightweight parts and will often blow in spectacular fashion if run for more than a handful of laps.
Grid: The starting order of the field, in the physical positions that they will actually start the race. Also refers to the part of the track where cars are assembled pre-race.
Groove: (1) The line or path through a corner which drivers have found to be the fastest. Where the groove is depends on a huge number of factors, such as the type of paving, the car weight, tires, downforce, driving style, track and weather conditions, etc. It is not uncommon for the groove to change during a long race, particularly on a dirt track. (2) Channels that are cut or molded into the tread portion of the tire. These grooves make up the tread pattern.
Grooving: A term used when a tool with a blade is used to alter the tread pattern of a tire. When using this tool it will create a new groove in the tread surface. The size of the groove varies and depends upon the width of the blade being used. This method is used to increase traction by giving the tires more edges on the tread surface to grip with.
Ground Effects: Use of airflow under the car to create downforce. (The term "ground effects" comes from aviation, but there it means the opposite: the tendency of an airplane near the ground to float on a high-pressure cushion of air.) Most ground effect cars use passive tunnels to create a venturi effect, which draws air from under the car.
Growing: In racing, when tire circumference increases as speeds increase. Tire growth is important in heads-up classes where speed determines the race outcome. Less contact patch on the top end leads to more M.P.H. In oval track racing, when the circumference of a tire increases due to heat and pressure build up. Tire growth alters the stagger, and upsets the handling of the car. One advantage of radial tires is that they don't grow.
GTA: GT American Road Racing Association.
Guard Beam: Light beam positioned 16 inches ahead of the stage beam to prevent racers from using side panels behind the front tires to block the staging beams, thereby gaining a starting line advantage. If the guard beam is reached before the car leaves the staging beam, a red light is given and the car disqualified.
Gurney Flap: A small spoiler-like tab that sticks up (or down) perpendicular to an aerodynamic surface, such as a wing; it has the effect of increasing air pressure on that side of the surface, making it produce more force in one direction or the other. Perfected in the early '70s by legendary Indy car driver and designer Dan Gurney.
Gusset: A reinforcement addition adding web-like or triangulation reinforcement to car structure, usually welded in place.
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H

Hairpin: A slow, tight 180-turn which exits in the opposite direction a driver enters.
Half-Shaft: In a car with independent suspension on the rear wheels, the part that carries the engine power from the rear end to the wheels. (Or the front wheels on a front-wheel-drive car.) The half shaft must have some kind of mechanism in order to be able to move with an independently-suspended wheel, while still being able to transmit torque to the wheel; universal joints or constant-velocity joints are commonly used. The half shaft is so called because it is "half an axle".
Halftime: A scheduled break in a race that occurs when half of the scheduled laps have been completed. A red flag is flown, and all cars go to the pits for 5-10 minutes, where work can be done. The halftime is used when a racing series wants to de-emphasize the importance of pit stops. The NCTS series dropped it because they found that, eventually, there was little racing taking place in the first half of the race; teams were simply using the first-half laps as a test session in order to put in a finely tuned chassis setup during the halftime. May also refer to a competition yellow.
Halon: Special Freon Fire Extinguisher. Generally a 3% to 5% concentration will extinguish fire.
Hammer Down: The driver has the gas pedal "to the metal"- full throttle. 
Handicap: In bracket racing, when one car is faster than the other, the slower gets a head start. Handicaps are based on previous elapsed times or dial-ins.
Handling: A general term for the racecar's capability to go where the driver wants it to go on the track, and be fast in the process. See loose and push.
Hanford Device: A type of rear wing used by CART on superspeedways. The Hanford device is intentionally designed to produce very high aerodynamic drag, in an effort to slow down the extremely fast CART cars on superspeedways. Results have been mixed; the racing that results is sometimes compared to the effects that restrictor plates have had on Winston Cup.
HANS Device: Head and Neck Restraint System. A driver restraining system that straps over the driver shoulder and securely attaches the helmet to anchors to reduce the snapping motion of the driver's neck during an impact.
Happy Hour: The final hour of practice before an event, usually held the day before the race day and after all qualifying sessions and support races have been staged.
Hard Charger: The driver that has passed the most cars in the race.
Harmonic Balancer: An element used to reduce vibration in the crankshaft.
Harness: The safety belt system worn by a race driver. The basic racing harness is a "four-point" unit; it has four belt lengths that meet in the middle of the driver's pelvis. Two points form a conventional lap belt, same as in a passenger car; the other two go up the chest and over each of the driver's shoulders; unlike a passenger-car shoulder belt, they do not cross over the chest. In cars with a roll cage, they are fastened to a roll cage member behind the driver's seat. (In open-cockpit cars, such as Indy cars not having a roll cage, they are fastened to the part of the chassis structure behind the driver's seat.) The place where the four points meet has a one-lever disconnect that causes all four harnesses segment to unfasten simultaneously, for rapid bailout. Some series require a "five-point" harness, which adds a belt that goes through the crotch and the bottom of the seat; this prevents "submarining" (a term for when the driver slides out from under the lap belt in a high-speed frontal impact). Some shoulder harnesses have a horizontal strap that connects them and crosses the breastbone; this is called the "sternum belt", and it prevents the driver's breastbone from extruding out from between the shoulder belts.
Hat Dance: A routine performed by the winning driver where he is photograph in victory lane with each of the sponsors and sanctioning bodies hats.
Hauling The Mail: A term used by drivers to describe going really fast. 
Head Sock: A fireproof hood that covers the entire face (except eyeholes), head, and neck. Usually worn under a full-face helmet. Also referred to as a "balaclava".
Head Wrench: Slang term for a race team's crew chief.
Headers: Fine-tuned tubular exhaust system routing exhaust from engine. Replaces conventional cast exhaust manifolds.
Heads Up Race: In drag racing, when two cars from the same classification in stock and super stock meet in an elimination round.
Heat Cycle: Refers to the number of times a tire is run up to operating temperature and then allowed to fully cool.
Heat Race: A preliminary race to a feature. Heat races are generally short, 8-15 laps in distance. They serve to get both the cars and the fans warmed up for the feature, and sometimes the outcome of the heat races is used to determine the starting order of the feature.
Heel: The area of the bead that describes to transition radius between the vertical and horizontal surfaces.
Heel and Toe: When a driver uses his right foot to operate both the accelerator and brake pedals. Used on tracks that demand a lot of shifting.
Hemi: (1) A type of cylinder head where the combustion chamber is roughly in the shape of a hemisphere. Generally the valves are opposite each other on the dome of the head, with the spark plug centered; this results in better breathing and ignition characteristics. A distinguishing and peculiar characteristic of a hemi engine is that the spark plugs are underneath the valve covers, and require metal tubes to shield the plug insulators from the oil. Hemi engines are not seen much in Stock car racing anymore, but are still quite common in Indy car and drag racing. (2) An engine manufactured by Chrysler through about 1956-1971 with this type of cylinder head.
Hides: Slang term for tires.
High and Dry: When a racecar becomes too high on the track and loses one or more positions.
High-Centered: To get a car hung up on a curb in a "see-saw" position so that neither the front nor the rear wheels has traction. (This is easy to do with racecars, which generally have little ground clearance.) The car can't move until it is pushed off the curb.
High Groove: The line or path on the track nearest to the outer wall. Where the groove is depends on a huge number of factors, such as the type of paving, the car weight, tires, downforce, driving style, track and weather conditions, etc. It is not uncommon for the groove to change during a long race, particularly on a dirt track.
High Heat: Describes over heating of a tire usually 260 degrees or hotter.
Hitting Your Marks: The best spots on the track to either get on or off the throttle. Also may refer to the best line or spots on the track in which to run.
Hobby: A general name for a beginner-level Stock car class or division. Also sometimes referred to by names such as Rookie, Street, Cadet, etc. Hobby classes are usually based on older-model sedan bodies (the early '70s Chevelle/Impala is common), and engines with production blocks and intake manifolds. However, some Hobby classes are actually Mini Stock cars.
Hole Shot: A drag racing term for beating an opponent off the starting line and winning a race despite having a slower elapsed time. Other racers use this term to describe a good start or restart.
Hood: Panel that protects and allows access to the engine.
Hood Pins: Metal and wire tethers used to secure the hood.
Hooked Up: A car that is performing great because all parts are working well together. 
Horsepower: Used to measure the strength of any engine or motor. One horsepower equals 33,000 foot-pounds per minute or the force needed to lift 33,000 pounds at one foot per minute.
HOSS: Hoosier Outlaw Sprint Series.
Hot (track or pits): The condition of the track and pits when racecars are on the track (whether at speed or not). For safety reasons, tracks have restrictions on who can be in the pits or garage area when the track is hot.
Hot Lap: Running at race speed or near race speed during practice or testing.
Hot Shoe: Slang term for a fast driver.
HSCRA: Historic Stock Car Racing Association.
Hub: The part that connects the axle to the wheel.
Humpy's House: The Charlotte (Lowe’s) Motor Speedway located in Concord, North Carolina, just north of Charlotte, Because of the famed race promoter, as well as president and general manager of the speedway, H.A. 'Humpy' Wheeler. 
Hundredths: 1/100^th of a second. Used in timing lap times. The second digit to the right of the decimal point.
Hunting the Bottom: Slang term for a racecars ability to cut into the turn well and stay on the bottom of a corner.
Hutchens Device: Driver's head and neck restraint system.
Hydraulic: When a cylinder fills with too much fuel, thus prohibiting compression and causing a mechanical malfunction, usually an explosive one. Most often seen in Nitro-methane-powered classes such as Top Fuel and Funny Car.
Hydroplaning: A skimming effect caused by tires losing contact with a surface covered with water.
Hysteresis: The rate that a rubber compound bounces back to its original shape after pressure has been applied.
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I

IDBA: International Drag Bike Association.
Idiot Light: Can refer to a light that alerts the driver to a malfunction (as in a passenger car), but in a racing context, it usually refers to a large, attention-getting light that alerts the driver that the brake and/or clutch pedal is being depressed. Such a thing is used to cure drivers of "riding" the brake or clutch with the left foot.  
Ignition: An electrical system used to ignite the air-fuel mixture in an internal combustion engine.
IHRA: International Hot Rod Association.
ILMS: Intermountain Late Model Series.
IMCA: International Motor Contest Association. Probably the oldest existing sanctioning body in the world, IMCA has been sanctioning Modified and Stock car racing, mostly on dirt, in the U.S. Midwest and West since the '30s. In the '90s, IMCA experienced a surge in popularity, as their Modified rules became very popular with promoters looking for a low-cost formula. Not to be confused with IMSA.
Impact Wrench: A powered wrench that uses a combination of torque and a hammering action to loosen and tighten fasteners. Racers often use this term (improperly) as a synonym for air wrench.
IMS: Intermountain Mini-Sprints.
IMSA: International Motor Sport Association, the former name of the sanctioning body now known as Grand American Road Racing. This body was formed in the early '70s to sanction professional sports car racing in the U.S. IMSA sanctions the 24 Hours of Daytona.
IMTRA: International Mini-Truck Racing Association.
In Contention: In general, describes a car that has a legitimate shot at a race victory.
Inboard Brakes: Refers to the mounting of a car's braking mechanism inside the car body, rather than on the wheel as is usually done. The advantage of inboard brakes is that they reduce the wheels' un-sprung weight, which improves handling. 
Increasing Radius Corner: A turn that has a smaller radius during the first half of the corner.
Independent: A driver who owns his own racing team, and relies on race winnings as much or more than sponsorship money to finance his racing.
Independent Suspension: A type of suspension where an axle does not support connecting wheels, but by suspension members that support each wheel separately.
Index: 1) Elapsed time assigned by a sanctioning body such as NHRA or IHRA that defines a class (8.90 is the standard index for Super Comp in NHRA). Index may be altitude adjusted. 2) An index also allows various classes to race together with an equitable handicap starting system.
Index Finger: When shown during a caution period, indicates that one lap under yellow remains, and that the green will be waved on the next lap. This is also indicated by the pace car turning off its flashing lights.
Indy Cars: An open wheel formula using small-displacement, methanol- burning, engines. Named after the Indianapolis Motor Speedway, where they have raced since 1909, Indy cars are the only American oval-track racing types that have been heavily influenced by direct European involvement. Beginning in 1995, there are two organizations sanctioning Indy car races in the U.S.: CART and the Indy Racing League. The CART series includes both ovals and road courses, although the current schedule includes more of the latter; the IRL runs only on ovals.
Indy Racing League (IRL): A sanctioning body, owned and run by Indianapolis Motor Speedway president Tony George. The IRL conducts a series of Indy car style racing using cars that resemble (but are less expensive than) cars as sanctioned by CART. The IRL runs exclusively on ovals. Formed in 1995.
Infield: The area enclosed by the racecourse. Typically, the infield contains the pits, the garage area (if there is one), and spectator areas (at most larger tracks). Some large oval tracks have road courses running through their infields. However, at some short tracks (particularly dirt tracks shorter than 1/2 mile), the pits are located outside the track, and the infield is just an unpaved, unoccupied area. Oval variants such as the tri-oval and the quad-oval have their pits distant from the front stretch, and the open area separating the two is also referred to as the infield.
Inline: Commonly used to describe an engine with all cylinders and valve stems in a single row.
Inner Liner: A safety device for racing tires. An inner liner is a sort of tire-within-a-tire; it has its own air containment and its own valve stem separate from the main carcass of the tire. The inner liner is inflated to a pressure higher (usually 12-15 psi) than the main carcass. Inner-liners are not suitable for racing on, but they are good enough to allow the driver, in the event of a blown or flat tire, to retain control long enough to get the car slowed down and get to the pits without wrecking. The modern inner liner tire was invented by Goodyear and introduced to racing via Winston Cup in 1965. Also referred to as a Safety Liner or Safety Sheild.
In/Out Box: Contains direct drive slider gears on a Sprint Car. Since Sprint Cars do not have a clutch, the car has to be put in gear to be ready to race.
Inside Line: The shortest line around the track. Also, the part of the track that is closest to the infield.
Inspection: A specific set of guidelines set by the race officials that all competitors must adhere to. Generally, there are two main categories of inspection, safety and rules inspection. Seats, harnesses, brakes, and steering are usually safety inspections while engine offset, wheel width, tires, and body specifications are all forms of rules inspection. Inspection can be done anytime during an event, but most safety inspections are done only pre-race. Rules inspections are sometimes done pre-qualifications, post-qualifications, and post-race. When a series requires drivers to use the same tire in qualifications as in the race, tire marking is also done and checked in inspection.
Intake Manifold: A housing that directs the air/fuel mixture through the port openings in the cylinder heads.
Intermediate: A tire that is intended for use in damp or slight rain conditions.
Intermediate Track: A racetrack that is usually more than one mile but less than 2 miles in length.
Interval: The time-distance between two cars. Referred to roughly in car lengths, or precisely in seconds.
Interval Timers: In drag racing, interval timers are part of a secondary timing system that records elapsed times, primarily for the racers' benefit, at 60, 330, 660, and 1000 feet.
Inverted Start: A starting order where the first qualifier starts last, the second qualifier starts next-to-last, and so on. Most often seen in asphalt short track racing to increase competition and further entertain spectators.
IRA: International Racing Association or Interstate Racing Association.
IRL: Indy Racing League. A sanctioning body, owned and run by Indianapolis Motor Speedway president Tony George. The IRL conducts a series of Indy car style racing using cars that resemble (but are less expensive than) cars as sanctioned by CART. The IRL runs exclusively on ovals. Formed in 1995.
IROC: International Race of Champions. Sanctions like prepared cars and features selected drivers from different forms of racing.
ISA: International Stock Car Association.
ISMA: International Super Modified Association. Sanctions Super Modified racing in the United States and Canada.
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J

Jack Man: The member of a pit crew who operates the jack.
Jack Post: Sturdy post or rail on the side of the car where the jack man places the jack.
Jericho: A type of manual transmission, designed so that most gearshifts can be accomplished without using the clutch (except for shifting into gear from a dead stop). It accomplishes this trick using "dog-ring" shifters and straight-cut gears that can be mated at different speeds without clashing. Very popular in Winston Cup and BGN for use on road courses, and finding increasing use as an all-purpose transmission allowing for gear changes on ovals when necessary (such as at Pocono).
Jet: When air is sent at a high velocity through the carburetor, jets direct the fuel into the airstream. Jets are made slightly larger to make a richer mixture or slightly smaller to make a more lean mixture, depending on track and weather conditions.
Jumping The Start: When a driver anticipates the start (green flag) too early. This will cause a complete restart. Continued violations will result in a penalty.  
Junior Dragster: An entry-level class for children under age 16 in NHRA drag racing competition. Junior Dragsters are ½-scale versions of a traditional Top-Fuel Dragster. All components are aftermarket except for the 8 horsepower Briggs and Stratton mandated engines. Like Top-Fuel Dragsters, these machines utilize a tube chassis with a small roll cage encasing the driver, aluminum manual steering, narrow bicycle-type front tires, butterfly steering wheel, and fuel cells. Some differences include a chain drive system, solid rear axle, centrifugal clutch, and restricted fuel.
Junior Fuel: A class of drag racing that reflects the history of today's Top Fuel Class. Jr. Fuel cars look and perform like Top Fuel cars of the 60's. Traditional front-engine dragsters are combined with smaller engines, narrow tires, and restricted Nitro-methane fuel to produce drag racing like it used to be.
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K

KARS: Keystone Auto Racing on Speedways.
Kart: A very small, open-frame (no bodywork) single-seat car powered by a low-displacement engine similar to (but more powerful than) a lawnmower engine. Karts generally are direct drive with no transmission (although there are "shifter karts" which have gearboxes; these usually race at the advanced levels) and have wheels suspended by solid axles attached directly to the frame (no springs). Karts are raced both on ovals and road courses; oval races are often conducted on 1/16-mile bicycle velodromes. There are kart classes ranging from preteen children to professional. See also quarter midget.
Kevlar: A high stiffness, high strength material developed by DuPont. Used as tire cord because of its good mechanical and chemical properties at high temperature.
Kilopascal: (kPa) The metric unit for air pressure. There are 6.9 kPa's to one psi.
Kitty Litter: Slang term for Speedy Dry or other granular substances used to soak up oil, gas, or water spills.
KLASCAR: Keystone Legends Association of Stock Car Auto Racers. 
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L

Ladder Bars: A 3-point traction device with 2 attaching points at rear axle housing and 1 point at frame. Used to transfer traction back to rear wheels by changing pinion angle and preventing excess rear weight transfer.
Lap: One complete circuit around the track.
Lapped Car: A car, which is running, slows enough (or been in the pits long enough), such that the race leader has come all the way around the track and passed it, has been "lapped". This means that it has run at least one less lap than the leader.
Lapped Traffic: Cars that have completed at least one full lap less than the race leader.  
Late Apex: Turning into a corner late and missing the optimum apex point.
Late Model: A general name for an advanced-level Stock car class or division. These cars usually have purpose-built tube-frame chassis.
Lateral G's: Sideway force experienced while turning.
Lay Down Engine: All V-shaped engines are top-heavy. In the mid'50s (back when Indy cars were still front-engine), some chassis designers figured out that by tipping the engine on its left side, the engine could be made lower in profile. This placed its center of gravity lower and further to the left, a great benefit to the bulky roadsters of the day. This is called a lay down engine. It was very popular in Indy cars from about 1955 to 1965 (when rear-engine chassis took over that series), and is still seen in Super-Modifieds.
Lead Lap: The lap that the race leader is currently on.
Lead Foot: Slang term for a driver who is very fast, but is also rough on equipment and doesn't know when to take it easy. Lead foot drivers win many races, but they also break cars and crash a lot.
Lean: Running and lower fuel to air mixture. Drivers trying to conserve fuel will "run their engines lean" by using a decreased fuel/increased air mixture.
Left Foot Braking: A technique used on oval tracks where shifting gears at speed is not necessary. Braking with the left foot provides shorter reaction time, since the foot does not have to be moved from one pedal to the other. However, the driver must be careful not to "ride" the brake with the left foot. See also idiot light.
Legends: A Dwarf car, spec series promoted by Charlotte Motor Speedway owner Humpy Wheeler. Legends cars are built to tight specifications exclusively by 600 Racing. A sealed, 4-cylinder Yamaha motorcycle engine powers them, and no modifications are allowed to any components. Unlike most dwarf cars, which are open-wheeled, Legends cars have rudimentary fenders, as befits the body style.
LeMans Start: A type of race start where the drivers are outside of their cars, given a signal, then they must run to their cars, start the engines, and begin racing.
Let Go: Term to describe when an engine fails or "blows up." Also when other parts of a car fail.  
Lexan: A trade name of General Electric used for a durable thermal resistant plastic material used where transparent material is required (i.e.. face plates, goggles, windows, etc.)
Lift: To let off or “lift” your foot off of the throttle.
Lights Out: When the lights on the pace car, emergency vehicles, and track lights go out. Usually when the starter is ready to display a green flag during the last lap before the start or restart.
LIMCA: Long Island Mini-Cup Association.  
Limited: A general name for an intermediate-level Stock car class or division. These cars are more advanced than Street or Hobby cars; often they will be later-model bodies (some tracks permit drop-on one-piece plastic bodies in this class), and purpose-built chassis rather than production chassis. Most limited classes require a production based front clip on the chassis. Engines are less restricted, but retain some limitations (for example, many tracks require cast-iron blocks rather than aluminum). Class names include Limited Stocks, Limited Late Models.
Line: (1) The route taken by a driver, especially through a turn. The high line is a route close to the wall. A low line is closer to the track's infield and shortest distance around the track. (2) The painted line at the inside of the track usually considered the boundary line of the racing surface.
Linear Spring: A spring that compresses at a steady rate. For example, 1-inch of deflection for each 200 pounds applied. See Progressive spring.
Little Car: Encompasses a wide range of competition, which includes Mini-Champs, TQ’s (¾ Midgets), Mini-Cup cars and trucks, and Mini-Sprints.
LMTRA: Late Model Truck Racing Association.
Load Index: An assigned number ranging from 0 to 279 that corresponds to the load carrying capacity of a tire.
Load Range: DOT required specification. Calculation based on pressure, construction and speed. The average load a tire can bear without damage under set specifications.
Loaded Section Height: The height of the section of the tire that is making contact with the road.
Lock Down: To apply the brakes hard enough to totally lock the wheels during a spin. When a car's brakes are locked and all four wheels are sliding, the car will keep going in whatever direction it is currently going, regardless of which way the front end points.
Locked Rear End: Normal rear-end gears in a rear-wheel-drive automobile perform a "differential" function; when the car goes around a corner, they permit one wheel to turn faster than the other, to compensate for the fact that the wheel on the outside must cover a greater distance than the wheel on the inside. However, a normal differential also has a tendency to shift power to a wheel that is slipping, which usually results in worse slipping and causes loss of power and handling problems. A locked rear end forces both wheels to turn at exactly the same rate; this makes cornering more difficult but provides better acceleration. (A quick-change rear end often includes a "locking spool" that converts it to a locked rear end when inserted into the gear set.) See also ratchet rear end.
Long Block: Refers to a stage of assembly of an engine (and the state of assembly that engines might be sold in). Engine assembly ranges from "bare block", which is just an engine block with no moving parts, to "short block", which is a block with crankshaft, rods, and pistons (but no cylinder heads or valve train), to "long block", which is a complete engine less carburetor, manifolds, ignition, and accessories.
Long Pedal: Commonly refers to a car's gas pedal because of the design. Also used to describe a brake pedal when brakes wear out because the driver has to push the pedal harder and further to slow down.
Loose: A handling condition (known as "over-steer" to road racers) where, when the car goes through a corner, the rear end of the car wants to slide towards the outside of the turn. If the car gets loose enough, it will spin out. Loose is the opposite of push and under-steer.
Loud Pedal: The accelerator, gas pedal, or throttle.
Low Groove: The line or path on the track nearest to the infield. This is the shortest distance around the track but in some conditions it may not be the fastest. Where the groove is depends on a huge number of factors, such as the type of paving, the car weight, tires, downforce, driving style, track and weather conditions, etc. It is not uncommon for the groove to change during a long race, particularly on a dirt track.
Lug Nuts: Threaded nut that when screwed onto the lugs, attaches the wheel to hub.
Lugs: 1) Threaded stem or bolts that connects the wheel to the hub with lug nuts. 2) Large rubber blocks in the design of a tire tread.
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M

MACS: Mid-Atlantic Championship Series.
MAFCC: Mid-America Funny Car Circuit. 
Magnaflux: The process of using a special electromagnet and magnetic powder to detect cracks in iron, which may be invisible to the naked eye. Used to check chassis and engine components to detect potential problems before they occur. MANDRA  Mid-Atlantic Nostalgia Drag Racing Association 
MARA: Midwest Auto Racing Association. 
Marbles: Loose pieces of rubber or debris above the upper groove on the racetrack.
MARS: Mid-American Racing Series or Midwest All-Star Racing Series.
Maximum Inflation Pressure: The maximum air pressure to which a cold tire may be inflated; found molded onto the sidewall or specified by a tire manufacturer.
MCR: Midwest Classic Racers. 
MCSCC: Midwest Council of Sports Car Clubs. 
MDRA: Midwest Drag Racing Association. 
Meats: Slang term for tires. Mostly used in drag racing.
Memory Tach: A tachometer, which records its RPM readout over the course of a lap, or a few laps, and can replay the readout on command. Memory tachs are useful for diagnosing things like wheel spin coming out of a corner and some have features such the ability to display the highest RPM over the recording period.
Methanol: Technically pure methyl alcohol CH3oh (toxic) produced by synthesis.
Micro-Sprint: Form of racing using ½ scale sprint cars.
Midget: An open wheel car formula using short wheelbase chassis with driver enclosed in a roll cage and the engine in front of the driver. Midget cars run on ovals exclusively. Engines are usually 4-cylinder, normally aspirated. At one time, outboard (boat) motor engines were popular for use in Midgets, but recently production-based, aluminum, four cylinder engines from Ford and Dodge have appeared. The best-known Midget series are sanctioned by USAC.
M.I.G.: Metal Insert Gas Arc welding. Uses a continuous-feed filler rod material pulled through the torch from a roll of wire.
Mini-Sprint: Form of racing using ½ scale sprint cars.
Mini Stock: A general name for a class or division based on '70s or '80s compact-car models such as the Ford Mustang, Pinto, and Pontiac Sunbird. These are characterized by lightweights and 4-cylinder engines, with the level of rules and competition being otherwise similar to a Hobby class. This type of class is becomingly increasingly popular as old 4-cylinder compacts are plentiful.
Minimum Weight: The lowest allowed weight for the vehicle in its class. Can be measured pre or post race.
Mirror Driving: Driving while paying an inordinate amount of attention to a car or cars behind (while paying less attention to one's own line); especially, driving so as to make it difficult for faster cars behind to pass. Usually considered poor form.
MLRA : Midwest Late Model Racing Association.
MMA : Michigan Modified Association.
MMRA: Miniature Motorsports Racing Association.
MNMRA: National Motorsports Racing Association. 
MNNA: National Modified Midget Association.  
Modified Midget: Form of racing using ½ scale sprint cars.
Modifieds: These are open-wheel, enclosed-cockpit, front-engine cars that race mainly on ovals. Some have external framing, often known as "nerf bars", to add chassis stiffness, and to protect the front end and sides of the car. There are a number of formulas, ranging from very cheap (IMCA's) to very expensive (NASCAR's). Racing may be on dirt or paved ovals depending on the formula. Engines are stock-block, and use gas and/or alcohol depending on the formula. Modifieds have seen a revival in many parts of the U.S. over the last decade. See also Super modified.
Modulus: A measurement of a given materials stiffness and how much it deforms in response to stress. Usually referring to rubber.
Moonpie: Slang term for a serious, dedicated, and very excitable race fan.
Mount: Installing a tire on a rim or wheel.
MOVRC: Midwest Old-timers Vintage Club.
MPH.: Miles per hour. 
MPSA : Midwest Pro Stock Association. 
MRA : Midwest Super-modified Association.
MSCS : Midwest Sprint Car Series or Midwest Super Comp Series.
MSRA : Modified Stock Racing Association. 
MST : Montana Sprint Tour.
MVRCA: Maine Vintage Racing Car Association.
MVSCC: Mid-state Vintage Stock Car Club.  
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N

NAMARS: North American Auto Racing Series
NAMRA: North American Mini-Champ Racing Association.  
NASA: National Auto Sport Association sanctions road racing.
NASCAR: National Association for Stock Car Auto Racing. The top promoter of stock car racing in the U.S., NASCAR sanctions series ranging from the Winston Cup series, through regional racing in the South, Southwest, and Northeast (U.S.), down to local Saturday night racing. It also sanctions regional Modified racing in the Northeast.
NBS: NASCAR Busch Series.
NCMA: Northern California Modified Association.
NCRA : National Championship Racing Association.
NCS: Nextel Cup Series.
NCTR : National Dirt Truck Racing. 
NCTS: NASCAR Craftsman Truck Series.
NEAR : New England Antique Racers. 
NEMA : Northeastern Midget Association. 
NESCC : New England Sprint Car Club.
Neutral: (1) A position of transmission in which the engine and the drive train are not engaged. (2) A term driver's use when referring to how their car is handling when a car is neither loose nor pushing tight. 
NFCA: Northeast Funny Car Association. 
NHRA: National Hot Rod Association sanctions national drag racing events.
Nitro: Short for nitro methane, an oxygen-containing exotic fuel. Mix ratios are generally 90% methanol to 10% Nitro-methane.
Nitrous: Short for nitrous oxide (N2O), the same stuff that the dentist puts you to sleep with. When injected into an internal-combustion engine, it provides extra oxygen (being about 35% oxygen, as opposed to air, which is 21% oxygen), and gives the engine a boost similar to the effect of a turbocharger. Sometimes used in performance passenger vehicles but more commonly seen in Pro-Modified and Pro-Street Drag Racing.
NLMSS: National Late Model Series, Southern Dirt Tour
NLRA : Northern Late Model Racing Association 
NMCA : National Mustang Racing Association
NMMA: National Modified Midget Association. Sanctions modified midget racing in the United States.
NMRA : National 3/4 Midget Racing Association and Ford Racing Series  
NNCS: NASCAR Nextel Cup Series.
Nomex: A trademark for a fire-resistant fiber often used in fire suits. Originally invented by Du Pont for NASA in the early '60s, Nomex was introduced to racing in 1970, and has enormously improved the safety of the sport. There are now other fibers around that do the same thing, such as PBI and Kevlar, but Nomex is still a popular choice.
Nominal Rim Diameter: The diameter of a tire rim, given in nearest whole numbers (e.g. 15")
Non-Fill: Small portions of the tire that did no completely fill in during expansion in the tire press. Cosmetic in nature and most often occur on sidewalls of tires.
Normally Aspirated: Term for an engine that does not employ turbo charging or supercharging. Most Stock, Midget, and Sprint car racing engines are normally aspirated. IRL mandated normally aspirated engines in its Indy car series starting in 1997.
NOS: (1) Abbreviation for New, Old Stock. Refers to new but older products or replacement parts. (2) Abbreviation for Nitrous Oxide Systems.
Nosing Over: When a racecar's performance "flattens out" or doesn't pull down the straights anymore. Poor tuning or exceeding the engine's power range cause this.
Nose Wing: An airfoil, used to generate down force to improve steering capabilities. It is normally around 3' x 2' in size.  The wing is usually mounted directly above the front axle.
Novelty Racing: A form of racing, which relies on a trick or gimmick to make it appealing to the fans.
NORA: Northeast Organized Racing Association.
NOSA : Northern Outlaw Sprint Association and Sprint Invaders.
NSCA : Nebraska Sprint Car Association.
NSRA : Northwest Sprint Car Racing Association. 
NSS : Nostalgia Super Stocks. 
NST : Northern Sprint Tour. 
NVRA: National Vintage Racing Association. Sanctions vintage oval track racing.
NWCS: NASCAR Winston Cup Series.
NWMS : Northwest Modified Series.
NWSST: Northwest Street Stock Tour.
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O

OCRS : Oil Capital Racing Association.
O.E.: Original Equipment (as originally produced and installed by factory that manufactured automobile.) Originally equipped.
O.E.M.: Original Equipment Manufacturer. Original Automobile Manufacturer.
O.H.C.: Overhead Cam.
Off-Camber Turn: A corner with negative banking (the inside edge of the corner is higher than the outside edge). Seldom if ever seen on ovals, but some road courses have them.
Off-Road: (1) A form of racing which runs on an unpaved, ungraded course. Traditionally, this is a point-to-point, natural-terrain open course (for example, the Baja 1000). But, as environmental concerns have restricted the use of natural-terrain courses, forms of off-road racing using unpaved, purpose-built closed courses (e.g., the Mickey Thompson series) are becoming more popular. Note that racing on dirt ovals is never referred to as "off-road". (2) A phrase used in advertisements for racing parts and supplies to refer to the fact that a part may not be legal for use in a car that is driven on public roads.
Offset: (1) Weight: The difference in weight between the left and ride sides of the car. On an oval track, handling is improved by having as much weight over to the left as possible, so car builders usually offset the weight to the left as much as the series rules permit. (2) Chassis: A physical offset of the body between the wheels, accomplished by making the right side suspension parts longer then the left. Again, this is done to improve handling. (3) Drivetrain:  An offset of the engine to the left side of the car body. See also lay down engine. 4) Wheel offset: the distance between the centerline and the mounting face.
Oil: Liquid use to lubricate mechanical parts.
Oil Pump: A device that distributes oil throughout the engine to lubricate all moving parts.
On the Bubble: The last position available to qualify for the race. 
One-more-lap Signal: A signal to the drivers that the green flag will be flown on the next lap. This usually consists of two things: the flagman holding up one finger, or a furled flag in the shape of a one, to the field and the pace car turning its flashing lights off.
Open Competition: A series or event in which there are no specific rules governing the use of a “spec” or specified part such as a tire.
Open Hand: Indicates that five laps remain in the race.
Open Wheel: Cars that have their wheels exposed with no fenders such as Sprint Cars and Midgets.
Opposite Lock: A technique for taking corners on a dirt track (particularly one where the surface is loose or muddy). This involves turning the car left into the corner and accelerating to make the rear end slide out. The wheel is then turned right all the way to the stops (the "opposite lock"), and the throttle is used to make the car go around the corner -- more power makes the car looser, less makes it push. This technique provides faster corner entry and exit speeds on a dirt track than standard driving techniques.
Option Tire: An alternate tire made available by a tire manufacturer for a particular race. Often the option tire is made from a softer compound, which means that it will generally be faster but will not last as long and may be prone to blistering. IRL permits tire manufacturers to make option tires available to teams; NASCAR, ASA, and most other oval-track series generally do not. CART did prior to 1998, when a rules change effectively banned the practice.
OSCA: Outlaw Street Car Association.
OSCAAR: Ontario Stock Car Association of Asphalt Racing.
Otto Cycle: The four operations of intake, compression, power, and exhaust that constitute one revolution of a cylinder in a 4-cycle engine. Also called a cycle. Named for inventor Dr. Nikolaus Otto.
Out Brake: A driver gains time and position on an opponent by applying the brakes later and deeper into a corner.
Outlaw: A race run without the supervision of a sanctioning body, or a track that runs such races. In an outlaw race, the promoter or track owner usually does the job of forming and enforcing the rules. The term goes back to the '40s and '50s, when sanctioning bodies jealously guarded "their" member drivers and teams, and those who participated in an outlaw race were often penalized by fines, loss of championship points, and/or suspensions. (At one time, sanctioning bodies also regarded events sanctioned by other organizations as "outlaw". See also ACCUS.) 
Oval: In general, a somewhat circular racecourse containing only left-hand or right-hand turns. The actual shape of the track is often not, strictly speaking, oval: other shapes include Tri-oval, Quad-oval, D-oval, Rectangle, and Triangle. (See individual definitions) Ovals are nearly always run in the counterclockwise direction. In standard Stock car usage, there are three categories of ovals, as classified by their lengths: Short tracks, which are less than one mile in length. Intermediates, which are at least one mile but less than 1-1/2 miles in length. Superspeedways, which are 1- 1/2 miles or greater in length. Note that the IRL uses a different classification. In IRL usage, a 1-mile track is a short track (the IRL doesn't race on tracks shorter than one mile), and anything longer than 1 mile is considered a superspeedway.
Overall Diameter: The diameter of the inflated tire, without any load.
Overall Width: The distance between the outside of the two sidewalls, including lettering and designs. Also known as section width.
Overflow: Usually refers to the line from the radiator cap's relief valve. On a passenger car, this goes to a catch bottle, but on a racecar, it is usually allowed to vent. Some Stock cars bring the vent line out from under the hood cowl, so that escaping steam or water is visible to the driver on the windshield. Some series regulate where the overflow vents.
Overhead Cam: An engine having the camshafts positioned atop the cylinder heads, as opposed to a pushrod engine (see). These fall into two classes: Dual-overhead- cam (DOHC) designs have two camshafts over each bank of cylinders; generally one cam operates the intake valves, and the other the exhaust valves.
Overhead Valve: An engine having the valves in the cylinder head, above the top of the piston. In the early days of internal-combustion engines, most engines were "flathead" engines, where the cylinder head was simply a flat plate (with holes drilled for the spark plugs), and the valves were openings in the side of the cylinder. Today, all automobile engines are overhead-valve. The term "overhead valve" is not to be confused with overhead cam.
Oversteer: A handling condition (known as "loose") where, when the car goes through a corner, the rear end of the car wants to slide towards the outside of the turn. If the car gets loose enough, it will spin out. Oversteer is the opposite of push and under-steer.
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P 

Pace Car: A car, which comes onto the track, in front of the race leader, and leads the field whenever a caution flag is in effect. The pace car has two important functions: setting the permissible speed during yellow flag periods, and gradually bringing the field up to speed at the race start and during a restart. In most cases, the pace car also runs at pit road speed so teams can determine what gear and rpm produce that speed.
Pace Lap: A lap just before the start of a race, where the pace car gradually brings the field up to racing speed. The purpose of the pace lap is to prevent big discrepancies in speed between different cars from developing; having all cars start the race at nearly the same speed makes the start much safer. May also refer to laps run before the official start of the race to warm engines and tires.
Pacer Light: At one time, Indy car racing had a rule, on oval tracks that required cars to maintain their separation during a caution period, rather than bunching up behind the pace car. The pacer lights were a set of sequenced signal lights around the periphery that was supposed to tell the drivers whether they were maintaining pace or closing in.    
Paddock: A road racer's term for what oval-track racers call the garage area. Sometimes, however, the "paddock" does not actually contain garages, but is simply an open area away from the racing surface, where cars can be worked on.
Panhard Bar: In a rear suspension, a lateral bar that prevents the axle from moving left or right. It is generally attached to the end of the axle housing on the left, and to a frame bracket on the right. Also called a track bar.
Parade Lap: The first lap taken by the field as the cars get under way, before the start of the race. The parade lap is run at a very slow speed. Its purpose is mainly ceremonial.
PASS : Pro All Star Series. 
PCDLMT: Pacific Coast Dirt Late Model Tour. 
Penalty Box: A NASCAR term for the assessment of a five-lap penalty, which is NASCAR's most stringent during-race penalty short of disqualification. Imposed for severe infractions, such as intentionally spinning or wrecking another car.
Penalty Spoiler: A spoiler, which is affixed by the officials to a car to make it slower (as opposed to the usual purpose of a spoiler). Penalty spoilers are sometimes used to equalize cars, which have illegal bodywork, allowing them to compete without the team having to rework all the illegal bodywork.
Photo Finish: Means the same thing that it does in horse racing: a finish that is so close that a photograph, taken at the moment of finish, must be examined in order to determine the winner. (Recently, high-speed video camera systems have been replacing photography for this purpose.)
Pick: Refers to when a car is trying to pass another car, the car under attack may pass closely by a slower car, such that the slower car is on the same side as the attacking car. The attacking car then has to back off, and get in line with the lead car in order to pass the slower car. 
Pick Up: Debris built up on the tires consisting of rubber bits or stones.
Pilot Chute: In drag racing, a spring-loaded device that pulls out the braking chutes from its pack.
Pinched: When a racecar squeezes another car into the inside or outside wall.
Piston: A round metal cylinder, which is attached to the top end of the connecting rod inside of the cylinder. The piston compresses the air/fuel mixture on the upward motion, and is pushed downward when the air - fuel mixture explodes. This downward motion then drives the crankshaft.
Pit Board: (1) A signboard on the end of a long pole that the pit crew uses as a flag to their driver, so that the driver can find the proper pit, and to indicate, when executing a pit stop, exactly where the driver should stop. (2) Back in the bad old days before drivers had two-way radios, the pit board was a chalkboard that the crew used to communicate with the driver. A crewmember wrote messages on the pit board (such as lap times, running position, or instructions on when to pit), took the board to the inside wall or the edge of the pit lane, and held it up as the driver passed by. Boards are used today when a driver's radio fails or in classes where radios are not permitted.
Pit Box: A rectangle painted on the pit lane that shows exactly the area where servicing is permitted for each team.
Pit Road/Pit Row/Pits: An area adjacent to the track surface (generally in the infield) where cars are serviced. The name comes from early days of racing in which the pits actually had holes or pits dug in the ground so the crew could work on the underside of the car.
Pit Stall: A rectangle painted on the pit lane that shows exactly the area where servicing is permitted for each team.
Planetary Transmission: A transmission in which the various gears revolve around one another. Consists of a sun gear, carrier with planet gears, and ring gears. Also known as overdrive or underdrive.
Plate: (1) A Restrictor Plate: A device used to control power at tracks where the cars would otherwise be too fast for safety or insurance reasons. The plate is a machined slab of aluminum, about 1/20" thick, with four holes of a specific size. The plate goes in between the carburetor and intake manifold, and restricts the volume of fuel-air mix that may pass through. Use of restrictor plates has forced the development of a different class of engines, known as plate engines. (2) A Surface Plate: A large flat metal surface used as a dimensionally stable and level platform for the construction or alignment of a chassis.
Plate Engine: An engine designed to run with a restrictor plate.
Plowing: When the car is pushing up the track in the turns. 
Plug Check: During a practice or a qualifying session, if a driver shuts off the engine while at full power and then coasts into the pits, it is generally so that the crew can perform a plug check. The spark plugs are removed and the electrodes and insulator examined; the condition of these components (and particularly the color of the insulator) can reveal much about how the engine is performing. Running the engine at idle leaves deposits on the plugs that interfere with the plug check, and that is why the driver must shut off the engine while at full power, press in the clutch, and then coast in to the pits in order for a plug check to be done.
Plus-Sizing: An option allowing drivers to customize their vehicle by mounting low-profile tires on wider rims of one or two inches greater diameter, usually enhancing vehicle appearance, handling and performance.
Ply: A rubber-coated layer of fabric containing cords that run parallel to each other; extends from bead to bead.
P-Metric: Designation of tires built to DOT regulations. "P" indicates Passenger vehicle. Metric refers to the nomenclature and labeling requirements. Uniform designation of tire sizes, in metric measurements originally introduced by American tire manufacturers in 1977; commonly called "P-metric series." A typical P-metric tire is P205/70R14 93S.
Pneumatic: Refers to a device or tool that uses air for support or power.
Pneumatic Tire: A tire designed to use air for it support.
Points: A points system rewards drivers with points based on where they finish in a race, and may contain opportunities for earning bonus points by doing things like winning the pole position or leading a lap. At the end of the season, there is often a large cash award for the point's champion and perhaps other privileges such as first choice of pit positions all next season. The main objects of a points system are to discourage teams from skipping races, and to build up sustained fan interest over the course of a season. Many series have additional points systems for rewarding car owners, chassis/engine suppliers, etc.
Pole: The first starting position in a race; the inside of the front row.
Pole Sitter: The car occupying the first position in a race or the fastest qualifier for a race. Note that, due to qualifying procedures, the pole sitter may not always start from the first position due to inversion. In many racing series, the pole sitter has the option of starting on either the inside or outside of the front row.
Polish Victory Lap: An extra lap, run by the winner of a race, around the track in the reverse direction, and usually completed with a 180-degree spin at the start-finish line. The Polish victory lap was a creation of the late Winston Cup champion Alan Kulwicki, and several other drivers continue to do it in his memory.
Polymer: A long-chained molecule such as rubber. On a molecular level appearing like a bunch of interlocking spaghetti.
Pop-Off Valve: A mechanism used by CART to limit engine power in its turbocharged Indy cars. It is a valve that limits the pressure boost that the turbocharger can produce. If the boost pressure exceeds the pop-off valve's setting, the valve opens and vents the pressure, causing the engine to lose power. Also called a Hanford device.
Porpoising: An undesirable condition in which the racecar is bouncing up and down due to improper setup.
Port: The opening in an engine where the valve operates and through which the air-fuel mixture or exhaust passes.
Post Entry: A race team that enters a race after the race's official entry deadline has passed. Most sanctioning bodies will allow post entries to participate in a race, but will penalize it for the late entry monetarily or by not awarding it championship points for that race. When the abbreviation "PE" appears in a race box score in place of a car's points, it means that the car received no points because it was a post entry.
Powder Puff: A name used, back in the chauvinistic '60s, for a race or racing division where all the competitors were women. At many tracks, powder-puff races often consisted of wives of drivers or car owners in a very short race, using their husbands' cars.
POWER: Prototype Open Wheel Economy Racing Series. 
Power Plant: Commonly used term for engines.
PPI: Pounds per inch. A rating used in suspension parts such as shocks and springs. Used to measure the amount of weight that needs to be applied to attain 1 inch of travel.
Pre-Staged Light Beam: Light beam used to warn drivers they are inches away from starting line. This beam when broken by front wheels sets off pre-staged bulb on top of the Christmas tree.
Primary Sponsor: The sponsor that puts up the bulk of the sponsorship money for a race team, and consequently gets the most exposure on the car.
PRL: Provincial Racing League
Professional: A participant who makes his or her living off of racing. Unlike some sports, in auto racing there is no controlling body determining who is entitled to amateur or pro status, although some sanctioning bodies do require drivers to meet qualifications before they will be allowed to participate at certain tracks.
Profile: Used to describe the shape of a tire.
Progressive Spring: A spring that needs an increasing amount of force to increase deflection. For example, 1-inch of deflection for the first 200 pounds but the 2^nd inch of deflection needs 500 pounds instead of 400. See Linear spring.
Promoter: Someone who organizes a race, puts up the purse, gets race sponsors, handles advertising and ticket sales, and assumes the financial risk of putting on the race. The promoter might be a track owner, the owner of rights to a series, or an independent.
Promoter's Option: The traditional prerogative of the promoter, as the person who organizes a race, of designating one or more cars to start a race even though they failed to qualify. Promoters often reserved an option for themselves, so that they could be guaranteed that a popular driver would participate in the race. Some sanctioning bodies have discontinued the use of promoter's options in all of its touring series, and replaced them with the provisional start system.
Pro-Street: A highly modified streetcar. Pro-street cars generally feature large engines, blowers, narrow rear ends, and tubbed fenders. Older muscle cars like the Camaro and Chevelle are popular.
Protest: A complaint filed with officials, generally used to check for illegal components, scoring errors, or inappropriate driving techniques. Often, a fee is charged to file a protest, with the money returned if the competitor is found in violation.
Pro-Tree: The method of starting cars from starting line, using the Christmas tree. Method used is all three yellow bulbs light then green as opposed to one yellow light at a time then green (full tree). Also uses a reaction time of .400.
Provisional Start: A system used by many touring series that provides extra starting spots in the main event for teams that participate in a series on a regular basis. Provisionals are generally based on point standings, earnings, or past championship victories.
PSI: Pounds per Square Inch, a measurement of air pressure.
Pucker Factor: A high level of fear over an incident or difficult racing situation.
Pump Gas: Street-legal gasoline that can be purchased by the public. Used to distinguish from racing gasoline at many weekly racing tracks, the lower divisions are required to use pump gas (which has a relatively low octane rating compared to racing gas) as a way of limiting engine power and thus containing costs.
Punt: To bump someone from behind, usually causing a spin.
Purging: Process of removing air from a tire and replacing it with drier air, nitrogen, or another gas in order to lower humidity in a tire. This may be repeated several times in order to achieve even lower humidity.
Purse: The total prize money to be awarded to the race participants by the promoter. See also contingency awards.
Push: 1) A handling condition where the front wheels tend to slide when turning into a corner, which makes the car want to keep going straight. "Pushing like a dump truck" Push is the opposite of loose. Sometimes referred to as understeer. 2) Push starting a vehicle that will not, or does not have the capacity, to start on it's own. Sprint cars require a "Push" start.
Pushrod: 1) Engine: A rod that carries force from the camshaft of a pushrod engine, to a rocker arm (which transmits the force to the valve). The term also refers to engine designs that use pushrods. Such engines generally have a single cam, which on a V-shape engine is located in the "valley" between the cylinder banks. The pushrod valve train has more reciprocating mass than an overhead-cam design due to the long pushrods, and so usually cannot tolerate as high an RPM as an overhead-cam design. 2) Suspension: A link that connects the lower control arm to the spring/shock assembly
Pyrometer: In general, a heat-measuring device. The most common racing use is the tire pyrometer, which is used to measure surface temperatures of different areas on a tire and assist in chassis setup. Other common pyrometers include those designed to measure the temperatures of track surfaces, brake rotors, and exhaust headers.
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Q

QMA: Quarter Midgets of America.
Quad: Refers to a four-wheel all terrain vehicles.
Quad Oval: A tri-oval variant, which has two doglegs in the front straight instead of one, which increases the number of seats, which are directly in line with some part of the front straight. Charlotte and Texas are examples. (Atlanta, originally a conventional oval, was reconfigured to a quad-oval in 1997.)
Qualifying: The act of running a timed lap to earn a starting position in a race. In nearly all forms of oval track racing, qualifying consists of one car at a time running one or more laps to try to record the fastest time, for the best starting position. In road racing, groups, or flights, of cars are sent onto the track and their specific lap times are recorded as qualification times. In drag racing, cars are given individual qualification runs, often called "time runs," to prepare for the elimination rounds. In classes such as Super Stock and Comp, these qualification runs set elimination brackets. Finishing positions from heat race events can also be classified as "qualifying."
Qualifying Trim: Special setup used during qualifying whose purpose is to make the car go as absolutely fast as possible for only one or two laps. 
Quarter Midget: A miniature version of a Midget. Quarter midgets are very small single-seaters, similar in proportions to a kart, but with full bodywork and a sprung suspension. Most also have some type of roll cage.
Quarter Panel: The sheet metal on both sides of the car from the C-post to the rear bumper below the deck lid and above the wheel well.
Quick-Change: A type of rear end gear, which is designed so that the final drive ratio can quickly be changed without removing the rear end from the car.
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R

Race Rubber: Tires used just for the race as opposed to qualifying.
Race Safe System: A warning system that alerts a driver of a caution. Usually by an in car indicator light activated by a Race Official.
Racing Back to the Flag: When a caution or Yellow flag condition occurs and cars race to cross the finish line in order to better their restart position.
Racing Gasoline: Gasoline designed specifically for racing engines. Racing gas usually has very high octane.
Radial Ply Tire: A type of tire that's constructed with the reinforcing belts sideways (bead to bead) under the tread rather than lengthwise. The cords in the body of a radial tire run at or near 90-degree angles to the centerline of the tread. The combination of stabilizing belts and the radial casing allows the tread and sidewall to act independently. The sidewall flexes easily under load and greater vertical deflection is achieved with radial tires. When negotiating curves and encountering side forces, the independent action of the tread and sidewalls keeps the tread flat on the road. This allows the tire to hold to its path. This results in better overall handling compared to a bias tire. Radials also run cooler than a bias ply tire because there is less friction between the plies inside the tire. But radials tend to demand a much more precise line around each track, whereas bias-ply tires are more forgiving. This is related to the slip angle that each design needs for maximum grip. Radial tires work best at 1-2 degrees of slip and need 2-3 degrees of camber. For the driver this translates into a bigger window of feedback to feel the tire working. The other related factor is the drop off in grip that occurs if the tire is pushed beyond the optimum.  For bias ply tires, this tends to be a smooth transition that can be corrected, while with radial tires, the transition can be quite abrupt causing the car to loose control all at once. Radials are much more expensive to produce compared to bias tires.
Radius: 1/2 the diameter of a round object. The measurement from the center of an object extending to the outer surface.
Rain Tires/Rains: Tires used during wet conditions. Usually grooved to channel water away from the center of the tire in order to have a good contact patch. Also referred to as wets.
Rake: Term used to describe the angle of the chassis compared to the ground.
Ratchet Rear End: A rear end gear that locks under acceleration, and unlocks when the driver lets off the throttle. Commonly used in oval-track racing, where it provides the straight-line acceleration of a locked rear end, without the cornering difficulties.
RCCA: Race Car Club of America. Sanctions Formula racing events in the United States.
Reaction Time: In drag racing, this is the time elapsed before your front tires leave the staging beams after the green light is illuminated. Generally computed in thousandths of a second. .400 (pro-tree) and .500 (full tree) are perfect reaction times.
Rear Clip: The section of a race car that begins at the base of the rear windshield and extends to the rear bumper. Contains the car's fuel cell and rear-suspension components.
Rear End: Racer's term for the differential, the set of gears that transfers power from the driveshaft to the rear wheels. Racing rear ends may be locked. Stock cars usually require cooling fans or radiators to dissipate the heat that builds up due to losses that always occur when gears mesh at an angle.
Rectangular Track: A variant of an oval track that has the two numbered turns at each end of the track (which, in a normal oval, are combined into 180-degree corners) separated by "chutes", short lengths of straightaway. From the air, the track has the appearance of a rectangle with its corners rounded off. Indianapolis is the best-known example.
Red Flag: Race halted; all cars must drive slowly around to the start-finish line (or some other point designated by the officials) and then stop. Used when the track is blocked, or needs repair, or when weather conditions make it unsafe to continue even at caution speed. (In some series, a red flag comes out whenever a car rolls or flips, or other sufficiently serious accident occurs, so that emergency crews can get to the scene faster.) In most stock car racing series, all servicing of cars is prohibited while a red flag is in effect. However, in Indy car racing, servicing during a red flag is permitted.
Red with Yellow "X" Flag: Indicates that the pits are closed. When a caution occurs, the pits are closed until the pace car has entered the track and the field is formed up behind it). An official positioned at the pit entrance holds this flag. Any car that passes this flag and enters the pits is subject to a penalty. Some other series use a similar flag to indicate that there is an emergency vehicle on the track.
Redline: Usually, the maximum RPM that an engine can be safely operated at; indicated by a red pointer or painted line on the tachometer. Many modern racing engines have a rev limiter that will momentarily cut off the ignition to prevent the redline from being exceeded.
Relief Driver: A driver who, during a race, takes over a car for another driver who is physically unable to continue (due to factors such as illness, dehydration, or previous injury).
Rental Ride: When a team or driver pays a car owner for use of a team and/or car for an event.
Repeatability: A tires ability to be used many times.
Reset Fuel: Indy cars do not have fuel quantity gauges. Since Indy cars are equipped with engine computers, they have devised a method for estimating the amount of fuel remaining: by placing a flow meter in the fuel line, and having the computer integrate the flow over time, the computer can figure how much fuel has been used and subtract from the capacity of the tank to compute the amount of fuel remaining. The problem is, the computer has no way of sensing when the car is refueled, so the driver has a button on the dash or the steering wheel which must be pressed during a pit stop to inform the computer that the tank has been filled.
Restart: The term for the resumption of a race after a caution period.
Restrictor Plate: A device used to control power at tracks where the cars would otherwise be too fast for safety or insurance reasons. The plate is a machined slab of aluminum, about 1/20" thick, with four holes of a specific size. The plate goes in between the carburetor and intake manifold, and restricts the volume of fuel-air mix that may pass through. Use of restrictor plates has forced the development of a different class of engines, known as plate engines.
Retaining Walls: Barriers lining the inside and outside of a racing surface used to contain cars and debris from the spectators.
Retire: As used in racing, to drop out of a race due to mechanical difficulties or irreparable damage. Also used, however, in the conventional sense, as in to retire from the sport. 
Return Road: In drag racing, a road which leads from shutdown area back to the pits or staging lanes. Often, return roads are placed between the drag strip and the grandstands, allowing spectators to view the cars better and to reward great runs with rounds of applause.
Rev Limiter: A device that limits the maximum RPM that an engine can reach, usually by momentarily cutting out the ignition when the set limit is reached. The rev limiter (often a standard feature of modern racing electronic-ignition units) can be set to prevent the engine from exceeding its redline. Some sanctioning bodies have limits on maximum allowable engine RPM (as a power-limiting tactic), and use rev limiters to enforce these limits.
Reverse Cooling: A method of routing engine coolant to reduce differences in temperature between different parts of the head in block. A conventional cooling system has coolant from the radiator flowing into the block's water jacket, where it flows upwards towards the tops of the cylinders, from there into the head, and then finally into passages in the intake manifold which routes it back to the radiator. Reverse cooling, pioneered by Smokey Yunick, routes the cool water from the radiator directly into the cylinder heads, and particularly to the areas around the exhaust valves first, and from there downward through the block and then back to the radiator. This reduces temperatures around the exhaust valves (normally the hottest area in the engine), which in turn reduces pre-ignition and makes it possible to run higher compression ratios with the same fuel octane.
Rib Tire: A tire produced from the factory with only the circumferential grooves molded into the tread. Generally, rib tires are grooved by hand to match the track conditions.
Ride Height: The distance between the car's frame rails and the ground.
Riding the Rails: Used to describe a car or driver that is driving in the outer most portion of the track.
Rim: A wheel, technically, a metal support for a tubeless tire or a tire and tube assembly upon which the tire beads are seated. 
Rim Protector: Portion or extension of the sidewall of the tire that prevent rim damage during contact.
Rim Width: Distance between the two opposite inside edges of the rim flanges.
Road Course: A closed-circuit racecourse containing both left- and right-hand turns, and designed to approximate the experience of driving on open roads. Road courses may be built to run either clockwise or counterclockwise; they often contain changes in elevation or off-camber turns. By definition, road courses are paved. (Non-paved, non-oval circuits are termed "off-road" and fall into an entirely different class of racing.)
Roadster: (1) A general name for a single-seat or two-seat sports car. (2) In drag racing, a general description of a drag racing vehicle featuring an open cockpit, tubular frame, offset driving position, and cut down body from a passenger vehicle. Unlike an "altered", roadster body styles were originally American production cars including Ford and Chevrolet models. (3) In Indy car racing, the name used for the small, light front-engine cars that raced at Indy from about 1950 to 1965.
Rollback: A flatbed truck equipped with a winch, used to retrieve cars that have been so badly wrecked that they can't be towed.
Roll Bar/Roll Cage: The steel tubing inside the racecar's interior. A U- or V-shaped bar that protrudes from the top deck of an open-cockpit car, higher than the driver's head, such that if the car rolls, the car's weight will land on the bar instead of the driver's neck.
Roll Center: The theoretical point where suspension components intersect. This defines the point of rotation for the "lean' or "roll' when cornering.  In practice, this point changes as the suspension moves up and down. For racecar design it is used in connection with the center of gravity to predict and control weight transfer in the corners.
Roll Couple: Refers to the percentage of how much resistance to body roll is distributed between the front and the rear suspension systems. 
Rolling Resistance: The measured drag create by a driving surface, the tire, drive train parts, or a combination of all. The lower the rolling resistance, the less energy needed to keep a vehicle moving.
Rollout: The circumference of an inflated tire. The measured distance a tire will cover in one revolution.
Roof: Panel over the top of the driver's compartment.
Roof Flaps: A set of trap doors in the roof of a stock car. The roofs of these cars, since they are usually shaped somewhat in profile like an airplane wing, tend to generate lift when the car gets sideways, and on a superspeedway, this lift can be strong enough to actually fly the car off the track surface. The roof flaps are designed to open under these circumstances and kill the lift, both by venting air pressure inside the cockpit, and by breaking up the airflow over the top of the roof. (Usually, when roof flaps are installed, there are also small flaps in the windshield cowl.) Developed by legendary car owner and Ford consultant, Jack Roush.
Roof Net: webbing, similar to a window net that covers the opening in the top of the roll cage. Its function is to keep the driver's arms in the car in case the roof sheet metal gets torn off the car in a roll or flip. Invented by Robert Yates and Davey Allison.
Roof Strips: Strips of metal that run lengthwise on the roof of a stock car. These are designed to disrupt the airflow over the car if it becomes sideways. This kills the lift created and keeps the car from becoming airborne.
Rookie: In general, a driver who is inexperienced in the type of cars he/she is currently running. In most series a rookie is required to put a yellow stripe on the back of their car to notify other drivers.
Roller: A complete racecar minus an engine.
Rotating Mass: Somewhat misleading term for the combined angular momentum/inertia of all of a car's rotating propulsion parts such as the crankshaft, flywheel, and drive shaft. Engine and car designers have recently come to understand that high angular inertia has an effect on a car's ability to accelerate, and so reducing this has become a major preoccupation of designer. (Angular inertia is a function of both the mass of the rotating part, and by how far away the concentration of the mass is from the axis of rotation.)
Rotation: The changing of tires from front to rear or from side-to-side on a vehicle according to a set pattern; provides even tread wear.
Rotor: The disc portion of the brakes.
Round: When all cars in a bracket or class have made a run, usually, an elimination run.
Rounds: The number of revolutions a wrench, nut, or bolt is turned. One and a half rounds are one and half revolutions.
Rounds of Wedge: Adjusting the handling by changing the pressure of the rear springs. A wrench is inserted in a jack bolt attached to the springs, then turned “round” a number of times. This is used to tighten or loosen the amount of play in the spring. This directly changes the cross weight in a chassis setup. This in turn can loosen or tighten up the handling of a racecar.
Roundy Round: Phrase used to describe a circular or oval track.
Roval: Slang term that combines the two words Road (course) and Oval. Describes an oval track such as Daytona or Homestead that has a road course in the infield. Events such as the Daytona 24 hour race use the road course as well as a large portion of the oval track.
RPM: Revolutions Per Minute.
Rub: Light contact between two cars or two parts. 
Rubber: 1) The blend of rubber and other chemical and natural components that form the surface of a tire. Race tire rubber is not purely natural rubber, but a blend of natural and synthetic rubbers with chemicals and oils. 2) A semicircular wedge of rubber that is inserted between the turns of a coil spring to increase the spring's rate. Spring rubbers are often inserted into a spring prior to a race, when the team suspects that they will have to make a large handling adjustment during the race. If needed, the rubber can be quickly pulled out during a pit stop, for a larger change in handling than is possible by adjusting wedge or tire pressure.
Rubbing: Minor contact between cars. “Rubbing is Racing” is a phase used to describe the regularity of rubbing.
Run Under: In Drag racing, when your elapsed time is quicker than your dial-in, this causes you to be disqualified.
Running at Finish: A statistical classification; the opposite of DNF. A car is classified as having been running at the finish of a race if it crosses under the checkered flag. Note that this does not represent how many laps the car may have lost during the race.
Running Light: A car that is low of fuel.
Running the Double: Recent term for competing in the Indianapolis 500, and the Coca-Cola World 600 at Charlotte, in the same day.
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S

SAE: Society of Automotive Engineers. The professional association of transportation industry engineers that set standards for testing, measuring, and designing automobiles and its components.
Safety Bead: A hump that is present on the mounting flange of a wheel. This prevents the tire from unseating when air pressure is lost.
Safety Lap: An extra lap or laps run at racing speed after taking the checkered flag.
Safety Liner/Shield: Same as an inner liner. A safety device for racing tires. An inner liner is a sort of tire-within-a-tire; it has its own air containment and its own valve stem separate from the main carcass of the tire. The inner liner is inflated to a pressure higher (usually 12-15 psi) than the main carcass. Inner liners are not suitable for racing on, but they are good enough to allow the driver, in the event of a blown or flat tire, to retain control long enough to get the car slowed down and get to the pits without wrecking. The modern inner liner tire was introduced to racing via Winston Cup in 1965.
Saloon Cars: A British term for Stock cars or sedans.
Sanctioning Body: An organization that sets and enforces the rules for a race or racing class or series.
Sandbagging: Deliberately running slower than the car is capable of, particularly in practice or the early stages of a race in order to surprise the competition in the race.
SARA : Southern Auto Racing Association. 
SAS : Southern All Star Racing Series or Sprint Asphalt Series. 
SATCAR: Sports And Touring Car Racing. 
Sawing On The Wheel: Expression describing when a driver turns the steering wheel back and forth in a rapid manner.
SBRA: Southern Bracket Racing Association.
SCCA: Sports Car Club of America, a body that sanctions a variety of road racing activities. The SCCA focuses mainly on sports car racing, and most of the SCCA's series and divisions are amateur or semi-pro, but its Trans Am series is a highly regarded pro series for (road racing) Stock cars. In addition to road racing, SCCA also sanctions hill climbs, rally, and Solo events.
SCCS: Stock Car Championship Series.
SCDCA: Southern California Dwarf Car Association.
SCOA: Sprint Car Owners of Arizona. 
Scoring Line: A line on the track, where a car's scorer registers the car as having completed a lap when the car crosses that line. At larger tracks, the scoring line (or lines) is often not the start-finish line and vice versa.
Scotch: Refers to good side bite or tire grip in the middle of a turn.
SCRA: Sprint Car Racing Association. Sanctions non-winged Sprint car racing events in the United States.
Scrub: When a tire does not rotate in the same direction or with the same speed as the car moves, it scrubs over the surface. This is sometimes done intentionally to heat, clean, and/or harden tires.
Scuffs: In general, any tire that has been used, but usually refers specifically to tires that have been run for a few laps, removed from the car, allowed to cool, and then put aside for later use. Scuffing changes the physical characteristics of the rubber, generally making it more durable. Under some circumstances, scuffed tires are faster than sticker tires.
Seat Time: Used to describe time spent in a racecar.
Section Height: The distance between to bead diameter and the outer diameter of the tire. This dimension is usually represented as a percentage of the tread width.
Section Width: The width of the tire at the widest point when mounted on the correct rim. This is typically located somewhere about the midpoint of the sidewall.
Seize: When an engine locks up due to mechanical failure. This may result from overheating or a part breaking.
Self-Cleaning: Said of high-banked tracks, where wrecked cars and debris tend to slide off of the corners into the infield. Drivers at such a track have to be careful when approaching a spin or wreck in progress, since the out-of-control car will eventually slide off the track to the apron or inside edge, and trying to duck under that car on the inside can be disastrous.
Self-Starting: An engine equipped with an onboard starter, as opposed to using an external starter, which is attached to the engine to start it, and then removed (or simply pushing the car to start it). Most forms of Stock car racing require self-starters while Indy cars use external starters. Pushing usually starts sprint and Midget cars, and tracks that host these classes usually have "push trucks" for the purpose.
SEML: Small Engine Motorsports League. 
Sequential Shift: A type of semi-automatic transmission where the driver can select the next highest or lowest gear by just moving a lever or pressing a button. Some sequential-shift gearboxes are purely mechanical, but in others actual movement of the gears, as well as operation of the clutch, is controlled electrically. Commonly used in CART, Pro-class drag racing, and some road racing.
Series: (1) Tires with the same aspect ratio, or relationship of height to width inside the tire. (2) Common description used for the races sanctioned by a specific organization (touring series).
Setup (chassis): The configuration of the chassis in order to achieve the desired handling. Generally this consists of a selection of springs, shocks, and other suspension components with the needed force and damping characteristics, plus adjustments like camber, caster, toe, wedge, and stagger. For open wheel cars, this may also include wing angles and Gurney flap selection.
Shake Down: Testing a brand-new car or engine. 
Shaving: A process of removing tread. It has been shown that a tire with a thinner slick tire performs better than a thicker treaded tire.
Sheet Time: Time spent in a hospital, or otherwise rehabilitating from an injury.
Shift Points: The best engine r.p.m. at which to shift gears. Some production and racecars have lights to indicate when a driver should shift gears.
Shimmy: Wobbling of wheels from side-to-side on a vehicle. Shimmying can be caused by a variety of factors, including improperly balanced tires, poor alignment and bent wheels.
Shock: Component designed to control the up and down movement of the suspension caused by weight transfer as well as changes in the road or track surface. A shock controls the speed at which the spring moves. Shocks are rated in pounds per inch (ppi) or how many pounds it takes to compress the shock 1 inch. The lower the rated ppi, the softer the spring and the higher the rated ppi, the stiffer the spring. Shocks are numbered for both compression and rebound. The compression of a shock is when it is being pressed down. The rebound is when it is being pulled back up. Shocks do not control the amount of weight transfer in a corner. They will however control how quickly the weight is transferred.  
Shoe: Term used to refer to a racecar driver. 
Shoes: Slang term for tires.
Shoe Up/Change the Shoes: Slang term for changing the tires.
Shoot Out: Two or more driver's that are racing for the victory.
Short Block: Refers to a stage of assembly of an engine (and the state of assembly that engines might be sold in). Engine assembly ranges from "bare block", which is just an engine block with no moving parts, to "short block", which is a block with crankshaft, rods, and pistons (but no cylinder heads or valve train), to "long block", which is a complete engine less carburetor, manifolds, ignition, and accessories.
Short Track: An oval track usually less than 1 mile in length. It is characterized by close, physically challenging competition, frequent contact between cars, and usually short races. The short straights and relatively slow lap speeds make handling and driver ability more important than engine horsepower.
Shoulder: The area of a tire where the tread and sidewall meet.
Showroom Stock: A racing series where new production cars are raced with very few or no modifications. Currently, this classification is limited mostly to road racing and Solo II events.
Shunt: British term for a collision.
Shutdown Area: In drag racing, the area located after finish line for racing cars to slowdown.
Shut the Gate: Slang term for blocking another car from passing.
Side Bite: A general term used to describe the amount of force available to hold the car in the apex of a corner. In car setup, putting more side bite in usually refers to reducing the sliding motion of a car in the corner.
Side Pod: The part of the body of an Indy car that extends into the space between the front and rear wheels. In a modern Indy car (since about 1972) design, the sidepods contain the engine's radiator and oil cooler; the sidepods contain tunnels that control the air entering the radiators for minimum drag, and funnel the exhaust air away from the wheels.
Sidewall: That portion of a tire between the tread and the bead.
Silly Season: Slang for the period during the latter part of the current season, wherein some teams announce driver, crew, and/or sponsor changes for the following year.
Silver Crown: A type of car defined by USAC, and the USAC series that runs these cars. Silver Crown cars follow basic Sprint car design except they're longer, heavier, and slower. Silver Crown is sort of the successor to the old front-engine Championship roadster cars that used to run Indy until the rear-engine cars took over in the '60s. Silver Crown cars are raced on ovals, about half paved and half dirt.
SIMS: Southern Independent Modified Series. 
Sipes: Special slits within a tread that can increase traction. Most often used in dirt track applications.
Sipping: A term used when a tool with a very narrow blade is used to alter the tread pattern of a tire. When using this tool it will create a slice in the tread surface. This process is used to help a tire take off better on starts and to also help with heat dispersion during a race.
Size: The combination of tire width, construction type, aspect ratio and rim size used in differentiating tires. May also refer to the circumference of a tire when inflated to race pressure.
Skid: To slip or slide on the road when tires lose their grip.
Slicks: Racing tires having no tread design, in order to get the maximum amount of rubber in contact with the pavement.
Slick Track: A track that has become slippery due to weather or a liquid spill.
Slide Job: A passing technique seen at dirt tracks. It involves diving into the bottom of a corner, under the car to be passed, at a speed far too high to maintain that line. As soon as the passer is clear of the car being passed, he allows the car to drift up the track in front of the car being passed and then slows to regain control. The car being passed is forced to slow down to avoid hitting the passing car. This technique is considered underhanded, and some series have tried to regulate it, with little success.
Slideways: Slang term that combines the words sliding and sideways. Means doing a combination of both.
Slingshot: When a trailing car is able to draft and attain a higher speed, allowing it to run up on the leading car and pass.
Slip: Elastic deformations of a tire during acceleration and cornering. These deformations affect the contact patch and ultimately the amount of grip.
Slip Angle: The angle between the direction the tires centerline are pointed and the direction the tires are actually going.
Slipstream: The cavity of low-pressure area created by a moving object. In racing, drivers use this slipstream to draft another vehicle.
Small Block: Usually refers to a small-block Chevy engine. This is by far the most commonly used engine in all forms of Stock car racing. Introduced in 1955, this engine design is probably the longest-lived internal-combustion engine design ever. A small-block Chevy is easy to spot by looking at its exhaust manifold; the two center cylinders have their exhaust valves (and hence the manifold runners) right next to each other, rather than regularly spaced as in the Chevy big-block and most Ford and Chrysler engines. See also big block.
SMART: Southern Modified Auto Racing Teams.
SMRA: Southern Midget Racing Association.
Snaking: On a superspeedway, driving a meandering path down a straight, in an attempt to cause following cars to get out of line and lose the draft.
Snow Tire: Sometimes called winter tire; a special type of tire with a tread and compound that gives better traction in snow; identified by the M+S, M&S, or M/S on the sidewalls. All-season tires must also include these designations on the sidewall.
SOD : Sprints On Dirt. 
Soft Walls: A type of racetrack wall construction that uses softer materials and spacer designs to absorb impact energy.
SOHC: Single overhead cam. 
SORA: Sprint 100's Racing Association. 
SOS : Southern Ontario Sprints  
SOSS: Southern Outlaw Super Series.
Spec: A type of rule that specifies a legal and required part by brand name or model, as opposed to a technical outline that leaves the choice of parts and brands up to the individual teams. Spec rules (tires are a common example) are often used by tracks to contain costs and to make enforcement easier.
Speed Rating: An alphabetical code (A-Z) assigned to a tire indicating the range of speeds at which the tire can carry a load under specified service conditions.
Speed Trap: On a drag strip, the final 66 feet to the finish line, known as the speed trap, where speed is recorded.
Speedway: A racetrack.
Speedy-Dry: A trade name for a granular mix of sand, cement, and resin used to soak up spilled oil, water, etc., from a racetrack. Has become the generic name in racing circles for any material used to soak up a spill.
Spin and Win: A race in which a car spins during the race but then ends up winning.
Splash-and-Go: A very short pit stop in which a small amount of fuel is added to the car and no tires are changed. Often seen near the end of a race, when a team calculates that they will be just short of having enough fuel to finish the race.
Splice: The point at which a one-piece tread or other tire components come together.
Split: 1) A measurement of time over a fixed distance, usually less than an entire lap. Seen mostly in road race and drag race timing. For example, the time it takes a car to go from turn 2 to turn 6 on a 13-turn road course. Can pinpoint places for improvement for the driver 
Split Valve Shock: A shock with a different rated ppi for compression and rebound.
Spoiler: An aerodynamic device used to increase downforce. On a Stock car, there typically is a spoiler on the rear edge of the deck lid, which produces downforce on the rear by causing air to "pile up" against the deck lid. Front spoilers were once similar, but now generally take the form of an "air dam" which not only deflects air upward but also prevents air from passing underneath the car, which produces downforce. The object is to improve the car's cornering speed, at the expense of increased drag. Minimum spoiler angles are required by most series.
Sponsor: A person or company who gives support money and/or products to a series, driver and/or team in exchange for advertising or some other benefit.
Spotter: Found in series where drivers are permitted to use radios. A spotter is someone who sits in a high place (typically on top of a grandstand roof) and watches their car, and the track ahead of their car. The spotter advises the driver when there is a car to their inside or outside, and when it is "clear" to pull into a lower or higher lane. When an accident occurs ahead of their car, the spotter warns the driver, and tells the driver which way to go to avoid the accident.
Spring: Coil springs are located at each corner of the chassis. The springs determine how much weight is transferred to each corner of the car. The springs are mounted in such a way that they can be adjusted up or down to change ride heights. Springs are rated by how many pounds it takes to compress the spring 1". The higher the rated spring the more weight it will take to compress the spring.
Spring Rate: Amount of force measured in pounds needed to achieve a certain amount of deflection. Used in rating springs and tires.  
Spring Rubber: A semicircular wedge of rubber that is inserted between the turns of a coil spring to increase the spring's rate. Spring rubbers are often inserted into a spring prior to a race, when the team suspects that they will have to make a large handling adjustment during the race. If needed, the rubber can be quickly pulled out during a pit stop, for a larger change in handling than is possible by adjusting wedge or tire pressure.
Sprint: An open wheel style of cars similar to, but somewhat larger than, Midgets. Engines are generally V-8, normally aspirated, and injected. Sprints are run on both dirt and paved ovals. Sprint cars are divided into two broad categories: winged and non-winged. The two sanctioning bodies best known for Sprint car sanctioning are USAC (non-winged) and World of Outlaws (winged). Economy classes of sprint cars have recently gained popularity including restricted engine classes like 305 and 360 sprints.
Spun Bearing: A type of engine failure. The main bearings (that hold the crankshaft in place in the block), and the rod bearings (that connect the rod to the crankshaft) consist of thin semi-circular pieces of special metal alloys that contain the rotating parts, and that the oiling system supplies with oil; a thin film of oil develops and keeps the metal parts from touching. If the film breaks down for some reason, the metal parts touch, and the force can cause the metal shells to revolve in the mounting that is supposed to hold them stationary. Usually, this leads to bearing meltdown and seizure of the rotating parts.
Squat: The action and ability of a racecars rear end to stay down in order to get good contact and grip.
Squirrelly: Used to describe an ill handling car, usually loose.
SRL: (1) Scale Racing League sanctions Mini cup, mini truck, and slingshot racing. (2) Super Modified Racing League. Sanctions Super Modified racing.
SSMA: Sourthern States Midget Association. 
Staged Light Beam: Light beam used to warn drivers they are on the starting line ready to race. This beam when broken sets off staged bulb on top of the Christmas tree. This beam also determines reaction time.
Stagger: A difference in circumference between the left-side and right side tires on a car. In a car with a locked rear end, rear-tire stagger will make the car want to continuously turn in the direction of the side with the smaller circumference tire.
Staging Director: A person who directs the flow of traffic from the staging lanes to the race lanes.
Staging Lanes: In drag racing, lanes located behind the starting line area where drivers line up and wait to make a run down the track. Usually, each class is called to the track by their particular staging lane.
Standing Start: A type of race starting setup in which the cars are lined up and started from a standstill instead of a rolling start.
STAR  : Senior Tour Auto Racers. 
STARS: Battle of the Bluegrass Tour.
Start and Park: Term to describe a car that starts the race then pulls into the garage after only one or a few green flag laps. This is usually done for several reasons: to fill out the field to meet the advertised car count, pick up prize money for a finish without spending money on the whole race, or for an owner to have continuity with a car number to acquire ABC points or awards.
Starter: (1) A device used to start an engine; a self-starter or an external starter. (2) A truck used mainly to push-start race cars commonly seen at Sprint and Midget races where the cars lack any other starting mechanism. (3) A flagman.
Start-Finish Line: A line on the track where the race officially begins and ends. The flagman's stand is usually at the start-finish line.
Static: Dimensions or descriptions that apply to an object that is not in use or in motion.
Steering: Changing the direction of a vehicle or the components used to do so.
Stick: The amount of tire grip present.
Stick-and-Ball: Race fans' derisive term for almost any sport other than auto racing, but particularly the American "big three" of baseball, football, and basketball. Hemingway once said: "There are only three true sports: mountain climbing, bullfighting, and auto racing. Everything else is just a game."
Sticker Tires: Tires that have never been run on a car, and still have the manufacturer's sticker on them. The stickers can easily be seen on the tires when a car equipped with sticker tires leaves the pits. See also scuffs.
Stiction: Slang term for tire grip. Combination of the words “stick” and “traction”.
Stock Cars: Cars based on the body and (sometimes) chassis of mass-produced streetcars. Stock cars can range from no-modifications-allowed Showroom Stock and Hobby/Bomber classes, to the Winston Cup cars which run with stock body shapes and stock-block engines, but are otherwise purpose-built racing cars.
Stock-Block Engine: The definition of this term is rather vague. In most usage's, it generally refers to an engine that is based on a production engine block design (specifically, that certain essential measurements of the block such as the cylinder-to-cylinder spacing or deck height are the same as on the production engine
Stop-and-Go: A type of penalty, which calls for the driver to drive the car to the pits, stops, and then immediately leaves again. This penalty is usually imposed for moderate infractions, such as going too fast in the pits, or passing improperly during a restart.
Stopping Short: A type of pit strategy which involves making a pit stop prior to the time where tire wear or fuel depletion would make it necessary. This strategy is often employed at tracks where the average lap time is greater than the time required to make a pit stop. If a caution period subsequently occurs before the competition has made their pit stops, the car that stopped short will stay out on the track, and thereby take the lead, when everyone else stops under the caution. It may also be used when significant speed differentials exist between new and used tires. This allows for cars that may be slower on used tires to put on fresh tires and enjoy the extra speed to regain track position.
Street Circuit/Course: A road course made up partly or wholly of partitioned-off city streets. CART and many open-wheel formula road-racing series run on street circuits. There is considerable debate about the quality of racing that ensues; often the streets are too rough for high-speed racing, and the necessary barriers placed along the street edge can result in single file racing with few passes.
Stressed Member: Term used for a method of construction, seen mainly in open wheel cars, where the engine, rather than being supported by the chassis, is part of the chassis. On an IRL car, for example, the tub ends behind the cockpit, and the engine bolts on to a bulkhead there; the gearbox, rear suspension, and rear wheels hang off of the engine with no further support from the chassis.
Stringing: A procedure for checking the toe of the front wheels. Basically, it consists of running a string down the side of the car; with the steering wheel pointed straight ahead, the distance between the front edge of the wheel and the string, and the rear edge of the wheel and the string, is then measured; the difference between the two distances gives the toe angle. This is a quick-and-dirty procedure, usually used for repairing crash damage during a race; it is not accurate enough to be used for critical adjustments.
Stroking: (1) Driving conservatively so as to preserve the equipment and stay out of accidents. Drivers who do this consistently are known as "strokers" and the term carries some scorn, but sometimes stroking is necessary when a car is known to have a problem that will prevent it from finishing if it is run at full speed. See also sandbagging. (2) Changing the piston stroke of an engine in order to increase or decrease its displacement, effectively making it a larger or smaller engine. Changing the crankshaft with one that has the rod journals farther from or closer to the crank's rotation axis does this.
Submarining: A term for when the driver slides out from under the lap belt in a high-speed frontal impact.
SUMA : Southern United Modified Association.
Supercharger: An air compressor, powered by the engine (via a drive belt, gear, or shaft), which forces more air into the engine. On most internal-combustion engines, the upper limit on power output at a given compression ratio is determined by the amount of air that can be forced into the engine (since about 15 parts of air are required to burn 1 part of gasoline). A supercharger raises the air pressure in the intake manifold, which makes it possible to shove in more air through the intake valves. Supercharging is common in drag racing, and is permitted in some series of Modifieds and Supermodifieds. Sometimes called a "Blower" or a "Huffer".
Super Modifieds: An extreme form of Modifieds, rapidly distinguished from them by the fact that Super Modifieds are open-cockpit. Super-Modifieds use an offset big block engine that produces 900 horsepower for an 1800-lb car.
Superspeedway: An oval track that is usually greater than 1.5 miles in length. Note that the IRL uses a different classification. In IRL usage, a 1-mile track is a short track (the IRL doesn't race on tracks shorter than one mile), and anything longer than 1 mile is considered a superspeedway.
SUPR : Southern United Professional Racing.
Surface Plate: A large flat metal surface used as a dimensionally stable and level platform for the construction or alignment of a chassis. 
SVRA: Sports car Vintage Racing Association. 
Sway Bar: See anti-roll bar. Bar used to resist or counteract the rolling force of the car body through the turns.
Sweeper: A large sweeping corner on a road or street course.
Switchback: An "S" like track configuration generally designed on a fast portion of a track to slow cars.
Switching Ignition: Changing from a primary to a backup ignition unit. The driver can change from one unit to the other, in a manner of a few seconds.
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T

Tachometer: Also referred to as a Tach. A gauge that measures revolutions per minute.
Tacky: A track condition where the racing surface is slightly wet and sticky.
Taking Rubber: A dirt track term describing when a racetrack loses its moisture and rubber from the tires begins to stick to the dirt surface, creating an asphalt-like condition. Tires wear much quicker in these situations and races are generally less interesting as only one lane develops the necessary traction. Can also refer to an asphalt track taking rubber.
Taking the Air: When two cars are close together and the lead car has less air being applied to its rear spoiler. This causes the car to have less rear downforce, which causes it to be loose in the turns.
Talent: Used to describe a driver’s ability. Could also describe announcers or on air commentators.
Tank Slapper: A violent oscillation in the front end of a motorcycle. So violent that the rider ends up repeatedly hitting or slapping the gas tank with his/her legs or another body part. Can also be used in auto racing to describe an accident in which a cars back end gets loose and slaps the wall or another car.
TBARA: Tampa Bay Area Racing Association.
T-Bone: An accident where one car runs into another hitting it at a 90-degree angle directly in the side.
T-Car: In Indy car racing refers to a backup car. Traditionally, in Indy car racing each car that a team brings to a race has to have its own entry filed (as opposed to the practice in NASCAR where one entry covers a team's primary and backup car). So that each backup car won't need its own car number, which would create chaos, the backup car is allowed to bear the same number as the primary car, but has a letter 'T' decal next to the number to indicate that it is a backup car; hence the term T-car.
TDCA: Texas Dwarf Car Association.
Tear-Off: (1) A layer of clear plastic that covers the visor on a full-face helmet. The tear-off is attached with a weak adhesive, and has a tab so that the driver can rip it off and remove it when it becomes dirty. Some tear-offs have several layers, each with its own tab, so that the driver can tear them off one at a time, as they get dirty. These are popular in all forms of dirt track racing. (2) A large layer, similar to those described above, which covers the entire outer surface of a windshield. It is torn off by a pit crewmember during a pit stop.
Tech: Short for Technical Inspection, an area and/or process in which Officials inspect vehicles for rule and regulation compliance.
Telemetry: A radio system that gathers data about the car's performance from sensors, and passes that data directly to the pits via radio, without any effort on the part of the driver.
Template: A metal, wood, or plastic cutout used to check the body dimensions of a car. Often used for Stock cars, which usually must conform to rules requiring them to maintain at least a semblance of the body shape of a production car model. NASCAR introduced templates in 1967.
Ten-Tenths: Slang term for running at the maximum.
Tenths: 1/10th of a second. Used in timing lap times. The first digit to the right of the decimal point. Sometimes even broken down to a half a tenth, which is equal to 5/100ths (five one hundredths) of a second.
Tethers: steel cables which are attached to the car's wheel hubs and assembly, as well as the hood and various pieces of sheet metal, to prevent these parts from flying off the car during a high speed crash. 
Thousandths: 1/1000th of a second. Used in timing lap times. The third digit to the right of the decimal point. Threshold Braking: Braking hard, but below the point where the tires lock up and begin to skid.
Throttle: The plate(s) used to control the air/fuel delivery system that controls the output of the engine. Also refers to the gas pedal and all components that control acceleration.
Tight: A handling condition where the front wheels tend to slide when turning into a corner, which makes the car want to keep going straight. Also called push or understeer. Tight is the opposite of loose and oversteer.
Time Runs/Time Trials: Also referred to as “Qualifying”. The act of running a timed lap to earn a starting position in a race. In nearly all forms of oval track racing, this consists of one car at a time running one or more laps to try to record the fastest time, for the best starting position. In road racing, groups, or flights, of cars are sent onto the track and their specific lap times are recorded as qualification times. In drag racing, cars are given individual qualification runs, often called "time runs," to prepare for the elimination rounds. In classes such as Super Stock and Comp, these qualification runs set elimination brackets. Finishing positions from heat race events can also be classified as "qualifying."
TIN: Tire Identification Number. An alphanumeric code mark located usually on the sidewall of a tire to identify a manufacturing batch or date.
Tire: An assembly of rubber, chemicals, fabric and possibly metal, designed to provide traction, cushion road shock and carry a load under varying conditions.
Tire Designation: An alphanumeric code molded into the sidewall of the tire that describes the tire's size, including width, aspect ratio, rim diameter, load index and speed rating. Most designations use the P-Metric system, although racing tires often use non-DOT nomenclature.
Tire Placard: A metal or paper tag permanently affixed to a highway vehicle, which indicates the appropriate tire size and inflation pressures for the vehicle.
Tire Rub: When a tire is coming in contact with part of the car.
Tire Run: The amount of laps or time run during the useful life of a set of tires.
Tire Rule: When a racing series mandates that competitors can run only one "spec" or specified brand of tires. See "Spec."
Tire Shake: A drag racing phenomenon when a loss of traction and/or tire distortion causes the tires to shake violently. Normally, the car becomes out of control and the driver's vision is blurred from the movement. See also back-pedaling.
Tire Softener: A solvent, which is applied to the surface of tires, changes the chemical characteristics of the tread rubber. Sanctioning bodies and most weekly tracks have banned the use of tire softeners because they are based on aromatic hydrocarbons (such as benzene or xylene), which are toxic with repeated exposure. They may also cause damage to the structure of the tire and increase the risk of failure.
Tire Stint: The amount of laps or time run during the useful life of a set of tires.
Tire Wear: The loss of rubber from tire treads due to use.
Toe: (1) This is the area of the bead that describes the point of termination of the bead. (2) One of the three major suspension geometry adjustments. The angle of the wheels, relative to the car's forward motion. With the steering wheel in the straight-ahead position, if the wheels are pointed inward the wheels are said to be "toed in"; the opposite condition is "toed out".
Toe Steer: Changes in the direction of a wheel or wheels due to deflection of suspension parts. Usually during cornering or driving on an uneven surface.
Top End: (1) The parts of the engine above the cylinders, including the cylinder heads and valves. Compare with bottom end. (2) The part of an engine's RPM range near the redline.
Top End Power: The amount a car accelerates at high speeds or in its highest gear.
Top Wing: An airfoil, used to generate down force to improve handling characteristics and improve traction. It's size is normally around 5' x 5'. This wing is generally mounted directly above the roll cage.
TORA: Topless Outlaw Racing Association.
Torque Steer: The tendency of a car to steer a certain direction when power is applied.
Torsion Bar: A rod in the suspension system that, when twisted from a grip at one end, functions like a spring.
TQ: Abbreviation for "three-quarter" midget, a sort of downsized Midget. TQ's are run at some tracks as a support division to train drivers for Midgets and Sprint cars.
Track: A racing surface. Racetrack or racing facility.
Track Bar: In a Stock car rear suspension, a lateral bar that prevents the axle from moving left or right. It is generally attached to the end of the axle housing on the left, and to a frame bracket on the right. Also called a Panhard bar.
Tracking: The direction an object is moving. May be different than the direction the object is pointing.
Track Out: The point on the track exiting a turn where the car comes closest to the wall.
Track Temperature: The temperature of the surface of the racetrack.
Track Width: Refers to the overall width of the axles, from their widest points. Usually, track width is measured from the centerline of one tire to the centerline of the other.
Traction: The friction between the tires and the road surface; the amount of grip provided.
Traction Control: Devices used to limit acceleration to only the amount beneficial for traction.
Trading Paint:  Slang term used to describe aggressive driving involving a lot of bumping and rubbing.
Trail Braking: When the brake is applied after steering into a curve. Traditionally in racing, brakes are applied while the front wheels are still steering straight. Trail braking may allow deeper braking into a corner, but if not done properly can very quickly result in massive oversteer.
Trailing Arm: A rear suspension piece holding the rear axle firmly fore and aft yet allowing it to travel up and down.
Tramping: A state in which a vehicle bounces up and down abnormally. If the bouncing is localized to the rear tires while under power, the car is said to be experiencing "wheel hop".
Trans Am: A road-racing series for sedans, sanctioned by the SCCA. Trans Am cars are based around American-made sports cars such as the Camaro, Firebird, and Mustang. In construction, the cars are almost identical to Late Model cars, with tube-frame chassis and plastic or fiberglass body panels, and pushrod V-8 engines.
Transfer Slot/Spot: In a race that uses heat races to determine qualifying for the feature or main race, the transfer slots are the finishing positions in the heat races that qualify the drivers who finish in those positions to advanced to the feature. Typically, this will be anywhere from the first six to the first fifteen finishing positions, depending on how many heat races there are and how many starting positions are available in the feature.
Transponder: A small electronic box, attached at the same point in each car, that sends out a small signal every time it crosses a fixed scoring point.
Transporter: A large tractor-trailer used to transport racecars and parts to a racetrack. Those used by teams in the major series usually have the space to carry two cars (one above the other), spare engines, transmissions, and axles, and a small workshop complete with machine tools, all in the trailer.
Traps: The two beams of light at the end of the drag strip which compute mile per hour.
Tread: The portion of a tire that comes into contact with the road.
Tread Depth: The usable thickness of the tread. Small pinholes, called depth holes, are placed in the tread so tread depth can be measured.
Tread Pattern: This refers to the groove design on the operating surface of a tire. Most patterns are molded into the tread at the factory, but a custom grooved tire is also said to have a tread pattern.
Tread Rib: The tread section that runs around the circumference of the tire separated by the tread grooves.
Tread Width: The width of a tire's tread.
Tread Wear Indicator: Narrow bands, sometimes called "wear bars," that appear across the tread of the tire when only 2/32 inch of treads remains. This applies to DOT type tires.
Triangular: A track has the tri-oval stretched out from the center of the track to the point that the track has three corners of nearly equal angle. At such a track, the dogleg is considered a numbered corner (unlike the other types of tri-oval, where the dogleg isn't numbered), and the other corners are numbered singly, instead of split into two halves. This means that triangular tracks have only three numbered turns instead of the ovals usual four. Pocono is the best example of a triangle track.
Tri-Oval: An oval track where the front straight is built with a dogleg (the word "tri-oval" is also the name used for the dogleg itself). The main advantage of this type of track is that, for fans in the front straight sitting around the curve of the dogleg, the cars appear to be coming straight at them, which makes for a better show. Daytona, built in 1959, was the first tri-oval.
Trip Strips: Small undulations on an open wheel driver’s helmet used to reduce buffeting and increase helmet stability at high speeds.
Tunnel: Underground entrance and exit to a tracks infield. Installed at many tracks to allow for smaller trucks and other traffic to access the infield without damaging or soiling the track.
Turbocharger: A device that uses engine exhaust pressure to drive a compressor, which forces more air into the engine, usually directly into the intake. See also supercharger.
Turbulence: Swirling, disrupted air.
Turn In: Location on the track where the driver starts to turn the steering wheel to enter the turn.
Turn Numbering: A numbering system that is used to refer to the individual turns of an oval. Since the typical 180-degree corners can constitute the bulk of an oval, they are split into two halves, which are numbered separately. Thus, the first half of the first 180-degree corner after the start-finish line is turn 1, and the second half of that corner is turn 2. The other 180-degree corner is numbered as turns 3 and 4. Thus, ovals are generally considered to have four turns
Turn Out: Location on the track where a driver turns the steering wheel back for exiting a turn.
TUSA: Team United Sanctioning Association.
Tweak: Minor adjustments.
Tweel: Combination of the two words tire and wheel. A single piece product that serves as both a tire and a wheel. The Tweel features a network of polyurethane spokes fused to a wheel hub and a circular outer flat rim that replaces the casing, beads and sidewall structures of a conventional tire. Attached to the outer surface is an underlying reinforcing belt covered with a flat rubber tread. The airless tweel uses a series of polymeric rings arranged radially around a wheel hub, to which is attached a reinforcing belt/tread package. Because Tweel-type units would be manufactured perfectly round, they would require no tire-to-wheel mounting or balancing, making them basically a bolt-on application.
Two Hundred MPH Tape: Also known as "racer's tape." Highly adhesive Duct tape strong enough to hold parts of the racecars body together at high speed.
Tyre: Alternate spelling for “tire”.
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U

UARA : United American Racing Association.
UDRA : United Drag Racers Association.
UDTRA: United Dirt Track Racing Association.
ULMS : United Late Model Series. 
UMARA: United Midget Auto Racing Association. 
UMP: United Mid-Western Promoters. Sanctions Late Model and Modified racing in the United States.
UMRA: United Midget-Racing Association.
UMSA : United Mini-Sprint Association.
Understeer: A handling condition where the front wheels tend to slide when turning into a corner, which makes the car want to keep going straight. Also called push or tight. The opposite of loose and over-steer.
Undertray: A portion of the underbody of a car that is sculpted to increase downforce.
Un-Lap: When a driver down one lap passes the leader to regain their position on the lead lap.
Un-Sprung Weight: The weight of the wheel, tire, and suspension parts that are not supported by the springs. More un-sprung weight means more inertia in the suspension, which usually means less responsiveness and poorer handling, so reducing un-sprung weight is a major preoccupation of suspension, wheel, and tire designers.
URC : United Racing Club.
USA: United SprintCar Alliance. 
USAC: United States Auto Club. This organization sanctions open-wheel racing including Silver Crown, Sprint, Midget, and Formula 2000 events from the Midwest to California.
USAR : United Speed Alliance Racing. 
USCS : United Sprint Car Series. 
USMTS: United States Modified Touring Series. 
USOMS: United States Outlaw Mini-Sprint Association. 
USRA: United States Racing Association. Sanctions weekly racing.
USTAR: Ultimate Short Track Auto Racing. 
USTCC : United Stated Touring Car Championship.
UTQGS: (Uniform Tire Quality Grading Standards) A tire information system that provides consumers with ratings (from A to C) for a tire's traction and temperature. Tread wear is normally rated from 60 to 620. Ratings are determined by tire manufacturers using government-prescribed test procedures, and are molded into the sidewall of the tire. 
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V

Valance: A panel that extends below the vehicles front bumper. This is used to divert air around the car and not allow it to travel under the car. This helps with increasing downforce.
Valve: A device used to start and stop the flow of a liquid or a gas.
Valve Core: This is the core of a valve stem. The core is depressed to apply or remove air from the tire through the stem. The core can be removed from the stem to increase the airflow.
Valve Float: What happens when an engine is run at an RPM higher than what the valve train is capable of operating at, resulting in the valves' failing to close completely during the compression stroke. Valve float causes loss of power and usually leads to engine damage.
Valve Stem: An assembly, metal or rubber that houses a valve cap to keep out dirt and moisture and a valve core to prevent air from escaping.
Valve Train: All parts related to the function of the valves.
VARA: Vintage Auto Racing Association. Sanctions vintage road racing.
VARC: Vintage American Race Cars. Sanctions vintage car oval track racing.
Vent Hose: On an Indy car, the alternative to a catch can for recovering fuel that overflows from the fuel cell during the refueling process. The vent hose plugs into the vent port and takes the overflow back over the pit wall to a tank for measuring and recovery.
Vent Man: On an Indy car, the pit crew's member who handles the vent hose. This person also handles the air hose for the car's built-in pneumatic jacks.
Venturi: An area of a device that reduces area in order to speed up flow.
Victory Lane: An area on or inside the track where the winner is honored after the end of the race.
Victory Lap: A celebratory lap taken by a race winner, after the race is over. Generally, the driver will remove helmet or gloves and wave to the fans. Some weekly racing venues don't give out trophies for heat races or other preliminary events, so on such occasions they may allow the winner to take the checkered flag and make a victory lap while holding it out the window. See also Polish victory lap.
VMRA : Vintage Modified Racing Association. 
VNT: Variable Nozzle Turbocharger.
VOTRC : Virginia Old Timers Racing Club.
VSS: Virginia Sprint Series. 
VTEC: Valve Timing and Lift Electronically Controlled.
Vulcanization: The curing portion of the tire manufacturing process when the tire is inserted into a press and heated to encourage polymer bonding and cross-linking.
VVT-I: Variable Valve Timing Intelligence. Refers to a computer controlled valve system rather than a hydraulically controlled one.
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W

"W": Can refer to an engine with its cylinders in a "W" configuration (three banks), but in the context of oval-track racing, this is usually understood to mean the Ford "Windsor" small-block V-8, which is a common alternative to the Chevy small-block in many forms of Stock car racing, and also serves as the basis for some Sprint car engines. (The name comes from the city in Ohio where the production block is manufactured.) See also Clevor.
Walking the Dog: Describes a driver who was lucky enough to hit the proper setup and is running away from the field.
Wally: Trophy given to all NHRA National Event winners. Named for series founder Wally Parks.
War Wagon: A large pit cart usually stocked with all the necessary components to rebuild a racecar after a wreck. These carts become popular in most all-traveling series when access to the team's trailer during a race was limited, or when returning to the trailer led to disqualification.
Warm-Up Lane: A paved lane, separate from the racing surface, that extends from the pit exit to some point further around the track. The idea is to give cars exiting the pits a separate area for coming up to speed, before they merge back in with the race traffic.
Water Burnout: Process of spinning your tires in water to get the tires hot and sticky for better traction.
WCAR: West Coast Auto Racing.
WCS : Wisconsin Challenge Series.
WDRA: Western Dirt Racing Association. 
WDRL: World Dirt Racing League.
Wear: The loss of material from a part due to friction.
Wear Bars: Raised sections of tread grooves that indicate only a small portion of tread depth remains. In race tires, wear bars usually appear at 2/16^th of an inch of tread remaining. Applies to DOT type tires.
Weaving: Zigzagging across the track to warm up and clean off tires.
Wedge: (1) In Stock cars, the dynamic weight balance of the car from corner to corner using a jackscrew at each corner, attached to the spring mount; turning the screw transfers weight to or from that wheel, altering the handling characteristics.  (2) Extra rubber inserted into the sidewall of a tire during construction to stiffen the tire.
Weekly Racing: Weekly racing at most tracks consists of several classes of racing, some amateur and some professional classes. Generally, each class will run qualifying, heat races, and a feature.
Weight: A measured piece of metal usually lead attached to a wheel by tape or clamped on. Used to balance a tire/wheel assembly to reduce vibration. 
Weight Jacking: The art of shifting a portion of the weight of a car to certain wheels or corners to improve tire grip and the cars handling.
Weight Transfer: The dynamics of weight being transferred. Side to side during cornering, to the rear wheels during acceleration and to the front during deceleration or braking.
WESCO: Washington Economy Sprints.
Wet Nitrous Setup: Injecting nitrous mixed with fuel.
Wets: Tires used during wet conditions. Usually grooved to channel water away from the center of the tire in order to have a good contact patch. Also referred to as rains.
Wet Sump: The type of oiling system used in most passenger cars, and in some racecars (usually the lower classes). In a wet sump, oil that isn't being used at the moment is stored in a sump, which is an area built into one end of the oil pan (under the engine), like the deep end of a swimming pool. The pan catches oil running down from the engine, and the oil runs into the sump, where a pump picks it up and forces it back into the engine. Compare with dry sump.
Wheelbase: The length of a vehicle when measured from the center of the front hub to the center of the rear hub.
Wheel Hop: A hopping action of the rear wheels during heavy acceleration. Traction is lost and regained in rapid cycles after power is applied to the rear wheels.
Wheelie Bars: Bars attached to the rear of the car to prevent excessive front wheel lift.
Wheel Packing: Dirt terminology for using racecars to smooth the surface of a dirt track. Prior to a race night, most dirt tracks are dug up and watered. In order to level and smooth the surface, cars turn slow laps, often clockwise, to pack the dirt down smooth prior to racing.
White Flag: A flag displayed to indicate one more lap remains in the race.
Wicker Bill: Also called a Gurney flap. A small spoiler-like tab that sticks up (or down) perpendicular to an aerodynamic surface, such as a wing; it has the effect of increasing air pressure on that side of the surface, making it produce more force in one direction or the other. Perfected in the early '70s by legendary Indy car driver and designer Dan Gurney.
Wicking: (1) Very slow loss of air pressure from a tire. (2) Process used in the manufacturing of tires to eliminate air pockets.
Wide-5: A wheel-and-hub system where the area that would normally be the center of the wheel is instead part of a star-shaped hub. The wheel itself has no center; the wheel's mounting holes are on small tabs protruding from the inside of the rim. Wide-5 wheels have the wheel studs close to the rim, supported by the much stronger hub, and so are immune from having the center ripped out of the wheel by cornering forces, as sometimes happens with regular wheels.
Windmill: Another name for a supercharger.
Window Net: Tight webbing that covers most of the left-side window of a Stock car, next to the driver. It prevents the driver's head and left arm from going out of the window in a left-side impact or roll, and it keeps crash debris from flying in the window and striking the driver's head. The window net unfastens at the top so the driver can get in and out. Developed in the mid-'60s.
Windscreen: The windshield or a transparent fiberglass surface on the front of a car designed to aid airflow and deflect turbulent air from the driver.
Wind Tunnel: Controlled environment in which cars are tested against a generated airflow. Used to test and improve aerodynamic characteristics of a racecar and its components.
Wing: As used in auto racing, the object of the wing is to provide downforce to stick the tires to the track, as opposed to the aircraft use of creating lift. Early wings were aircraft wing sections turned upside down, but nowadays most are purpose-built for racing. Some series permit cars to have hydraulic systems with cockpit levers allowing the driver to adjust the angle.
Winglet: Name given to any smaller body wing or aerodynamic device.
Winners Circle: Located in Victory Lane. The location the winning driver takes his car.
Winston Cup: NASCAR's top Stock car racing series whose primary sponsor was RJ Reynolds Tobacco Company who manufactures Winston cigarettes. Prior to 1982, this was referred to as the Grand National division.  Primary sponsorship was changed to Nextel in 2004.
Winston West: A NASCAR series in the western U.S., which uses cars similar to the Winston Cup cars. The series evolved from the old Grand National West series on the West Coast. Today, the cars are similar enough to Winston Cup cars that, prior to 1997, Winston Cup events in the West were also part of the Winston West series and awarded Winston West points. The Winston West series is generally considered to be at the same level of competition as the Busch North Series, and in 2003, NASCAR united the rules of both organizations and renamed that level of competition it's Grand National Division.
Wire-to-Wire: A driver who wins the race from the pole position.
Wishbone: Suspension member that connects the wheels to the chassis. Named this because it is shaped similar to a turkey wishbone.
WKA: World Karting Association. Sanctions kart racing in North America.
WMRA: Washington Midget Racing Association. 
WoO: World of Outlaws, a sanctioning body that sanctions Sprint car events across the United States. WoO cars are noted for their large wings (as opposed to USAC sprints, which aren't allowed wings).
Worst to First: When a car starts in the back at the beginning of a race and then wins in the end he is said to go from worst to first.
WOWMS: Wolverine Outlaw Winged Midget Series.
WRA : Western Racing Association.
Wrench: Slang term for a mechanic.
WRL : Welterweight Racing League or Western Racing League. 
WSOA: Winged Sprints On Asphalt.
WTQMA: Winged Three Quarter Midget Association.
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X

Xtreme: Late Model Dirt Car series formally known as the United Dirt Track Racing Association.

Y

Yaw Angle: The difference between the direction the front of the car is pointing and the direction the car is actually traveling.
Yellow Flag: A flag indicating that a wreck has occurred, or some other condition (such as rain, debris, or spilled oil) has made the track unsafe for racing at speed. In oval-track racing, when the yellow is in effect, all cars must slow to a safe speed, and passing is prohibited. Generally, a pace car will enter the track, and drive in front of the race leader to control the speed; passing the pace car or other cars is not permitted. Other cars can draw up into a pack immediately behind the leader; exact procedures vary from one series to the next. In road racing, there are two forms of a yellow flag. 1) Local yellow: drivers must slow and attempt no passes in the area where the flag is displayed. The rest of the track remains under green flag conditions. 2) Full-course yellow: all cars must slow to a safe speed, and passing is prohibited on all portions of the track.
Yellow Stripe: In many oval track series, a rookie driver is required to put yellow strips of tape on rear of their car. The purpose of this is to warn other drivers that they are approaching an inexperienced driver.
Yellow Tail: Slang term for a rookie driver. In most series rookies are required to have a yellow stripe on the back of their car.
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Z

Zig Zagging: Weaving across the track to warm up and/or clean off tires.
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