|INDYCAR RACING GLOSSARY OF TERMS
Adhesion: The maintenance of contact between two touching objects. Adhesion refers to a static condition, whereas traction (also
known as "grip") refers to a moving condition.
Aerodynamics: As applied to racing, the study of the interaction between air and the resistance and pressures created by the
passage of a moving car through the air.
Apron: The paved (and usually flat) portion of a racetrack that separates the racing surface from the infield. Generally, a concrete
wall or steel guardrail separates the apron from the infield.
Attenuator: A safety device made of carbon fiber and honeycombed aluminum mounted on the rear of the gearbox. Enhances
driver protection by absorbing much of the force of a rear impact.
Bite: Adhesion of a tire to the track surface.
Blister: Bubbles on the surface of a tire created by overheating of the tread compound.
Camber: Degree to which right-side tires lean in toward the car (from the top of the tire) and the left-side tires lean out. A useful tool
to gain grip in corners by maximizing the amount of tire-to-track contact.
Camshaft: A rotating shaft in the engine that opens and closes the engine's intake and exhaust valves.
Chassis: The central body of the car, including the dirver's compartment. Also referred to as the "tub."
Contact patch: The portion of the tire that makes contact with the racing surface. Various chassis and tire adjusments can be
made to maximize the contact patch.
Crankshaft: The rotating shaft within the engine that is turned by the up-and-down motion of the pistons. The crankshaft transfers
power to the flywheel, and in turn to the transmission. The crankshaft is housed within the crankcase, which is part of the engine
Diaper: A blanket made from ballistic and absorbent material that surrounds part of the engine and serves as a containment device
during accidents and engine malfunctions.
Disc: In brakes, the rotor, the part which revolves, and against which brake linings are pressed during braking.
Displacement: In an engine, the total volume of air-fuel mixture an engine theoretically is capable of drawing into all cylinders
during one operating cycle.
Downforce: Creation of force through aerodynamics, which keeps the car stuck to the track. High-speed movement of air
underneath the car creates a vacuum, while the wings on the car force it to stay on the ground, acting in a manner opposite to the
wings on a jet airplane.
Drafting: See "Tow."
Dyno: Short for "dynamometer," a static machine used to measure an engine's horsepower output.
Engine block: An aluminum casting from the manufacturer that contains the crankshaft, connecting rods and pistons.
Fuel injection: A system replacing conventional carburetion that delivers fuel under pressure into the combustion chamber of the
engine or air flow before entering the chamber.
Grip: How well the tires maintain traction through contact with the racing surface.
Groove/line: Term for the fastest or most efficient way around the track. Often most drivers will use the same groove around the
racetrack, and that portion of the track will consequently appear darker in color than the rest of the track due to the build-up of tire
Handling: A race car's on-track performance, determined by the factors such as tire and suspension setup, and other aerodynamic
Line: See "Groove."
Loose: The rear of the car is unstable due to a lack of rear-tire grip caused by too much front downforce, or not enough rear
downforce. Also known as "oversteer."
Marbles: Excess of rubber build-up above the groove on the track, the result of normal tire wear thoughout the race.
Neutral: Term used to describe the handling of the car when it is neither loose nor pushing (tight).
Nomex: Trade name of Du Pont, a fire-resistant fabric used in the manufacturing of protective clothing.
Pushing: The car does not want to turn in the corners due to a lack of tire grip. This can be caused by a lack of downforce on the
front of the car, or too much downforce on the rear of the car. Also known as "understeer" and "tight."
Rev limiter: Electronic/computer device in the engine controls which causes a controlled engine misfire if engine revolutions per
minute (rpms) exceed the limit set by Indy Racing League rules. The legal rpm (or "rev") limit for 2003 is 10,300 rpms. The rev
limiter is used primarily to control speeds, thereby increasing safety and controlling costs.
Ride height: The distance from the bottom of the chassis to the ground when a car is at speed. Indy Racing League rules stipulate
that the ride height of the sides of a car should be 2 inches off the ground for all tracks.
Short track: Racetracks that are 1 mile or less in length.
Side pod: Bodywork on the side of the car covering the radiators and engine exhaust. Aids in engine cooling, car aerodynamics and
driver protection in the event of a side impact.
Slick: A trakc condition where a car's tires do not adhere to the surface. This could be for a variety of reasons, such as a lack of
rubber on the surface (a "green track"), dirt on the track or high track temperatures.
Stagger: Right-front and/or right-rear tire is larger in diameter than left-side tires in order to improve turning ability on ovals.
Sticker tires: Slang term for new tires, derived from the manufacturer stickers placed on each brand-new tire.
Superspeedway: A racetrack of more than 1 mile in length.
Suspension & Wheel Energy Management System (SWEMS): Wheel-restraint system using multiple restraints attached at
multiple points to a car's chassis and suspension designed to minimize the possibilities of wheel assemblies becoming detached
during high-speed accidents. The restraints are made of FIA-approved Zylon. This material, with its high-tensile properties and its
wound construction (opposed to woven), has a breaking strength of 5 tons. The Indy Racing League introduced SWEMS in May
Telemetry: A radio device that relays information such as engine, tire, steering and throttle performance to team engineers in the
pits. The team can monitor both car and driver activity to ensure the car is performing properly. Also enhances driver safety by
allowing the team to notice any developing mechanical problem the driver cannot foresee.
Tight: Also known as "understeer." A handling condition characterized by a lack of grip in the front tires. As the driver steers through
a turn, the front wheels want to continue straight ahead.
Tire compound: A formula based on rubber polymers, oils, carbon blacks and curatives used to create a tire. The varying lengths
and banking of Indy Racing tracks require different compounds.
Tow/drafting: As a car moves around the track at 215 mph, it literally splits the air, some of which goes over the car, and some of
which goes beneath. This lack of air behind the car creates a vacuum, which a trailing car may use to be pulled, or "towed," by the
Tub: See "chassis."
Weight jacker: A hydraulic cylinder the driver uses to adjust car handling. The cylinder compresses or extends springs, which
transfers the car's weight distribution from one side of the car to the other, thereby adjusting the car's handling to the driver's liking.
Wicker bill: A long, narrow, removable spoiler made of steel, aluminum or carbon fiber on the trailing edge of the front and rear
wings which varies in height, creating downforce. Teams will use different sized wicker bills to create more or less downforce. The
larger (higher) the wicker bill, the greater the downforce, and vice versa for smaller wicker bills.