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Aerodynamics: As applied to racing, the study of airflow and the forces of resistance and pressure that result from the flow of air over, under, and around a moving car.
A-frame: Either the upper or lower connecting suspension piece (in the shape of an A) locking the frame to the spindle.
Adhesion: The “stick” between two touching objects. Adhesion implies a static condition, while traction implies a dynamic (moving) condition.
Air box: Housing for the air cleaner that connects the air intake at the base of the windshield to the carburetor.
Air dam: A metal strip that hangs beneath the front grill, often just inches from the ground. The air dam helps provide aerodynamic downforce at the front of the car.
Air filter: Paper, gauze, or synthetic fiber element used to prevent dirt particles from entering the engine. Located in the air box.
Air pressure: Force exerted by air within a tire, expressed in pounds per square inch (psi).
Alternator: A belt-driven device mounted on the front of the engine that recharges the battery while the engine is running.
A-post: The post extending from the roofline to the base of the windshield on either side of the car.
Apron: The paved portion of a racetrack that separates the racing surface from the (usually unpaved) infield.
Axle: Rotating shafts connecting the rear differential gears to the rear wheels.
Ball joint: A ball inside a socket that can turn and pivot in any direction. Used to allow suspension to travel while the driver steers the car.
Banking: The sloping of a racetrack, particularly at a curve or corner, from the apron to the outside wall. Degree of banking refers to the height of a track’s slope at its outside edge.
Bear grease: Slang term used to describe any patching material used to fill cracks and holes or smooth bumps on a track’s surface. Can also be used as a sealer on the track.
Bell housing: A cover, shaped like a bell, that surrounds the flywheel and clutch that connects the engine to the transmission.
Bias-ply: Layers of fabric within a tire that are woven in angles. Also used as a term to describe tires made in this manner.
Binders: Slang term for a race car’s brakes.
Bite: (1) “Round of bite” describes the turning or adjusting of a car’s jacking screws found at each wheel. "Weight jacking" distributes the car’s weight at each wheel. (2) Adhesion of a tire to the track surface.
Bleeder valve: A valve in the wheel used to reduce air pressure in tires.
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.
Blister: An overheating of the tread compound resulting in bubbles on the tire surface.
Blown motor: Major engine failure, for instance, when a connecting rod goes through the engine block. Usually produces a lot of smoke and steam.
Bodywork: The fabricated sheet metal that encloses the chassis.
Bore: Pistons travel up and down within each cylinder, or bore, in the engine block.
B-post: Post extending from the roofline to the base of window behind the driver’s head.
Brake caliper: The part of the braking system that, when applied by the driver, clamps the brake disk/rotor to slow or stop the car.
Camber: The amount a tire is tilted in or out from vertical. Described in degrees, either positive or negative.
Cam shaft: A rotating shaft within the engine that opens and closes the intake and exhaust valves in the engine.
Carburetor: A device connected directly to the gas pedal and mounted on top of the intake manifold that controls the air-fuel mixture going to the engine.
Chassis: The steel structure or frame of the car.
Chute: A racetrack straightaway
Compound: A formula or “recipe” of rubber composing a particular tire. Different tracks require different tire compounds. “Left-side” tires are considerably softer than “right-side” tires, and it’s against the rules to run left sides on the right. There are four basic components: rubber polymers, carbon blacks, oils and curatives.
Compression ratio: Amount that the air-fuel mixture is compressed as the piston reaches the top of the bore. The higher the compression, the more horsepower produced.
Contact patch: The portion of the tire that makes contact with the racing surface. The size of each tire’s contact patch changes as the car is driven.
Cowl: A removable metal scoop at the base of the windshield and rear of the hood that directs air into the air box.
C-post: The post extending from the roofline of a race car to the base of the rear window to the top of the deck lid.
Crank case: The area of the engine block that houses the crankshaft.
Crank shaft: The rotating shaft within the engine that delivers the power from the pistons to the flywheel, and from there to the transmission.
Cubic-inch displacement: The size of the engine measured in cubic inches.
Cut tire: A slice or puncture of the tread or sidewall due to high speed contact with debris on the race track or by contact with part of another race car.
Cylinder head: Made of aluminum, it is bolted to the top of each side of the engine block. Cylinder heads hold the valves and spark plugs. Passages through the heads make up the intake and exhaust ports.
Deck lid: Slang term for the trunk lid of a race car.
Dirty air: Aerodynamic term for the turbulent air currents caused by fast moving cars that can cause a particular car to lose control.
Donuts: Slang term for black, circular, dent-line marks on the side panels of stock cars, usually caused after rubbing against other cars at high speed.
Downforce: A combination of aerodynamic and centrifugal forces. The more downforce, the more grip your car has. But more downforce also means more drag, which can rob a race car of speed.
Draft: Slang term for the aerodynamic effect that allows two or more cars traveling nose-to-tail to run faster than a single car. When one car follows another closely, the one in front cuts through the air, providing a cleaner path of air, that is, less resistance, for the car in back.
Drafting: The practice of two or more cars, while racing, to run nose-to-tail, almost touching. The lead car, by displacing the air in front of it, creates a vacuum between its rear end and the nose of the following car, actually pulling the second car along with it.
Drag: The resistance a car experiences when passing through air at high speeds. A resisting force exerted on a car parallel to its airstream and opposite in direction to its motion.
Drive shaft: A steel tube that connects the transmission of a race car to the rear end housing.
Dyno: Shortened term for "dynamometer," a machine used to measure an engine's horsepower.
Engine block: An iron casting from the manufacturer that envelopes the crankshaft, connecting rods, and pistons.
Equalized: When the inner liner of a tire loses air pressure and that pressure becomes the same as that within the outer tire, creating a vibration. The inner shield should have a higher PSI than the outer tire.
Esses: Slang term used for a series of acute left- and right-hand turns on a road course, one turn immediately following another.
Fabricator: A person who specializes in creating the sheet metal body of a stock car. Most teams employ two or more.
Factory: A term designating the “Big Three” auto manufacturers: General Motors (GM), Ford, and Daimler Chrysler. The “factory days” refer to the periods in the 1950s and ’60s when the manufacturers actively and openly provided sponsorship money and technical support to some race teams.
Fan: An electrically or mechanically driven device that is used to pull air through the radiator or oil cooler. Heat is transferred from the hot oil or water in the radiator to the moving air.
Firewall: A solid metal plate that separates the engine compartment from the driver’s compartment of the race car.
Flat-out: Slang term for racing a car as fast as possible under the given weather and track conditions.
Flywheel: A heavy metal rotating wheel that is part of the race car’s clutch system, used to keep elements such as the crank shaft turning steadily.
Four-barrel: A type of carburetor.
Frame: The metal “skeleton” or structure of a race car on which the suspension parts and roll cage are mounted. Also referred to as a “chassis.”
Front clip: Beginning at the firewall, the frontmost section of a race car. Holds the engine and its associated electrical, lubricating, and cooling apparatus; and the braking, steering, and suspension mechanisms.
Front steer: A race car in which the steering components are located ahead of the front axle.
Fuel: Also known as “gasoline.”
Fuel cell: A holding tank for a race car’s supply of gasoline. Consists of a metal box that contains a flexible, tear-resistant bladder and foam baffling. A product of aerospace technology, it’s designed to eliminate or minimize fuel spillage.
Fuel pump: A device that pumps fuel from the fuel cell through the fuel line into the carburetor.
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.
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).
Gears: Circular, wheel shaped parts with teeth along the edges. The interlocking of these two mechanisms enables on to turn the other.
Greenhouse: The upper area of the race car that extends from the base of the windshield in the front, the tops of the doors on the sides, and the base of the rear window in the back. Includes all of the A, B and C pillars, the entire glass area and the car’s roof.
Groove: Slang term for the best route around the racetrack; the most efficient or quickest way around the track for a particular driver. The “high groove” takes a car closer to the outside wall for most of a lap, while the "low groove" takes a car closer to the apron than the outside wall. Road racers use the term “line." Drivers search for a fast groove, and that has been known to change depending on track and weather conditions.
Harmonic balancer: An element used to reduce vibrations in the crankshaft, located on front of engine.
Handling: Generally, a race car’s performance while racing, qualifying, practicing. How a car “handles" is determined by its tires, suspension geometry, aerodynamics, and other factors.
Hauler: The 18-wheel tractor-trailer rig that teams use to transport two race cars, engines, tools, and support equipment to the racetracks. Cars are stowed in the top section, while the bottom floor is used for work space.
Heat cycle: Each time a tire is raised to operating temperature is a heat cycle.
High heat: Above normal (260 degrees Fahrenheit) tire temperature.
Horsepower: A measurement of mechanical or engine power. Measured in the amount of power it takes to move 33,000 pounds one foot in a minute.
Ignition: An electrical system used to ignite the air-fuel mixture in an internal combustion engine.
Intake manifold: A housing that directs the air-fuel mixture through the port openings in the cylinder heads.
Intermediate track: Term describing a racetrack one mile or more, but less than two miles, in length.
Interval: The time-distance between two cars. Referred to roughly in car lengths, or precisely in seconds.
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.
Lapped traffic: Cars that have completed at least one full lap less than the race leader.
Lead lap: The lap that the race leader is currently on.
Line: See Groove
Loading: Weight at a given tire position on a car due to aerodynamics, vehicle weight and lateral G-forces in a turn.
Loose: Also known as “oversteer.” When the rear tires of the car have trouble sticking in the corners. This causes the car to “fishtail” as the rear end swings outward during turns. A minor amount of this effect can be desirable on certain tracks.
Loose stuff: Debris such as sand, pebbles, or small pieces of rubber that tend to collect on a track’s apron or near the outside wall during a race.
Lug nuts: Large nuts applied with a high-pressure air wrench to wheel during a pit stop to secure the tires in place. All NASCAR cars use five lug nuts on each wheel, and penalties are assessed it a team fails to put all five on during a pit stop.
Magnaflux: Short for “magnetic particle inspection.” A procedure for checking all ferrous (steel) parts (suspension pieces, connecting rods, cylinder heads, etc.) for cracks and other defect utilizing a solution of metal particles and fluorescent dye and a black light. Surface cracks will appear as red lines.
Marbles: Excess rubber build-up above the upper groove on the racetrack. Also known as loose stuff.
Neutral: A term drivers use when referring to how their car is handling. When a car is neither loose nor pushing (tight).
Oil pump: This device pumps oil to lubricate all moving engine parts.
Piston: A circular element that moves up and down in the cylinder, compressing the air-fuel mixture in the top of the chamber, helping to produce horsepower.
Pit road: The area where pit crews service the cars. Generally located along the front straightaway, but because of space limitations, some racetracks sport pit roads on both the front and back straightaways.
Pit Stall: The area along pit road that is designated for a particular team’s use during pit stops. Each car stops in the team’s stall before being serviced.
Pole position: Slang term for the foremost position on the starting grid, awarded to the fastest qualifier.
Post-entry (PE): A team or driver who submits an entry blank for a race after the deadline for submission has passed. A post-entry receives no driver or owner points.
Push: See Tight
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.
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.
Restart: The waving of the green flag following a caution period.
Restrictor plate: A thin metal plate with four holes that restrict airflow from the carburetor into the engine. Used to reduce horsepower and keep speeds down. The restrictor plates are currently used at Daytona International Speedway and Talladega Superspeedway, the two biggest and fastest tracks in NASCAR.
Ride height: The distance between the car’s frame rails and the ground.
RPM: Short for revolutions per minute, a measurement of the speed of the engine’s crankshaft.
Roll cage: The steel tubing inside the race car’s interior. Designed to protect the driver from impacts or rollovers, the roll cage must meet strict NASCAR safety guidelines and are inspected regularly.
Round: Slang term for a way of making chassis adjustments utilizing the race car’s springs. A wrench is inserted in a jack bolt attached to the springs, and is used to tighten or loosen the amount of play in the spring. This in turn can loosen or tighten up the handling of a race car.
Scuffs: Slang term for tires that have been used at least once and saved for further racing. A lap or two is enough to “scuff” them in. Most often used in qualifying
Setup: Slang term for the tuning and adjustments made to a race car’s suspension before and during a race.
Short track: Racetracks that are less than a mile in length.
Slick: A track condition where, for a number of reasons, it’s hard for a car’s tires to adhere to the surface or get a good “bite.” A slick racetrack is not necessarily wet or slippery because of oil, water, etc.
Slingshot: A maneuver in which a car following the leader in a draft suddenly steers around it, breaking the vacuum; this provides an extra burst of speed that allows the second car to take the lead. See Drafting.
Splash and Go: A quick pit stop that involves nothing more than refueling the race car with the amount of fuel necessary to finish the race.
Spoiler: A metal blade attached to the rear deck lid of the car. It helps restrict airflow over the rear of the car, providing downforce and traction.
Stagger: The difference in size between the tires on the left and right sides of a car. Because of a tire’s makeup, slight variations in circumference result. Stagger between right-side and left-side tires may range from less than a half inch to more than an inch. Stagger applies to only bias-ply tires and not radials.
Stick: Slang term used for tire traction, as in “the car’s sticking to the track.”
Stickers: Slang term for new tires. The name is derived from the manufacturer’s stickers that are affixed to each new tire’s contact surface.
Stop and Go: A penalty, usually assessed for speeding on pit road or for unsafe driving. The car must be brought onto pit road at the appropriate speed and stopped for one full second in the team’s pit stall before returning to the track.
Sway bar: Sometimes called an “antiroll bar.” Bar used to resist or counteract the rolling force of the car body through the turns.
Template: A device used to check the body shape and size, to ensure compliance with the rules. The template closely resembles the shape of the factory version of the car.
Tight: Also known as “understeer.” A car is said to be tight if the front wheels lose traction before the rear wheels do. A tight race car doesn’t seem able to steer sharply enough through the turns. Instead, the front end continues toward the wall.
Toe: Looking at the car from the front, the amount the tires are turned in or out. If you imagine your feet to be the two front tires of a race car, standing with your toes together would represent toe-in. Standing with your heels together would represent toe-out.
Track bar: A lateral bar that keeps the rear tires centered within the body of the car. It connects the frame on one side and the rear axle on the other. Also called the panhard bar.
Trading paint: Slang term used to describe aggressive driving involving a lot of bumping and rubbing.
Trailing arm: A rear suspension piece holding the rear axle firmly fore and aft yet allowing it to travel up and down.
Tri-oval: A racetrack that has a “hump” or “fifth turn” in addition to the standard four corners. Not to be confused with a triangle-shaped speedway, which has only three distinct corners.
200 mph tape: Also known as "racer’s tape." Duct tape so strong it will hold a banged up race car together long enough to finish a race.
Wedge, round of: Adjusting the handling of the car by altering pressure on the rear springs.
Wedge: Term that refers to the cross weight adjustment on a race car.
Window net: A woven mesh that hangs across the driver’s side window, to prevent the driver’s head and limbs from being exposed during an accident.