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Glossary

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ACTIVE DIFFERENTIAL
Computer-controlled differential used in World Rally that distributes engine's power to those tires with best grip to maximize performance.
AERO
Abbreviation commonly used when referring to the all-important science of aerodynamics.
AERO PUSH
When following another vehicle closely, the airflow off the lead vehicle does not travel across the following one(s) in a normal manner. Therefore, downforce on the front of the trailing vehicle(s) is decreased and it does not turn in the corners as well, resulting in an "aero push." This condition is more apparent on the exit of the turns.
AERODYNAMIC DRAG
A number that is a coefficient of several factors that indicates how well a race vehicle will travel through the air with how much resistance. Crewmen work to get the best "drag horsepower" rating they can, determining how much horsepower it will take to move a vehicle through the air at a certain mile-per-hour rate. At faster speedways teams strive to get the lowest drag number possible for higher straightaway speeds.
AERODYNAMICS
The science of understanding different forces acting on a moving element in gasses such as air. The application of this study to racing is credited with much of the sport's recent progress as teams learn more about drag, air turbulence and downforce.
AIR FOIL
In NHRA racing, the same as a wing - a stabilizer, generally used to create downforce, which increases stability and tire-to-track adherence at high speeds.
AIR PRESSURE
Mechanics can adjust a car's handling by increasing or decreasing air pressure in the tires. Flex in the sidewall of a tire acts like another spring in the suspension. Increasing the air pressure makes the overall spring rate stiffer, while lowering the pressure will make it softer. This adjustment can be made much more quickly and easily than changing a spring on a shock.
AIR WRENCH
This tool uses compressed air to quickly remove wheel nuts on contact. A crew member proficient with the air wrench can save a team valuable seconds on a pit stop. Also referred to as an air gun or impact gun.
ANGLE OF ATTACK
The angle of an Indy car style wing, the angle is varied from track to track to produce optimal downforce and minimize drag.
ANTI-LAG
World Rally electronic engine management program that reduces the normal delay in turbocharger response to a minimum.
ANTI-ROLL BAR
A bar linking suspension parts which can be adjusted to alter handling characteristics to compensate for tire wear and varying fuel loads.
APEX
Often heard in oval track racing, the apex is the geometric inside center point in a corner where a car is closest to the inside edge of the track. Drivers try to hit the apex to take the straightest line and maintain maximum speed. See also early apex and late apex.
ARMCO BARRIER
Similar to a highway guardrail, this corrugated steel crash barrier is designed to prevent a vehicle from leaving a race track or race course. AK Steel Holding, formerly known as Armco, now produces the barrier.
ASPHALT SETTINGS
The suspension adjustments made to optimise the handling of a World Rally car for smooth surfaced special stages.
ATMO ENGINE
Engine that uses natural, atmospheric air flow as opposed to forced induction. Used by NASCAR and NHRA Pro Stock cars while NHRA Top Fuel and Funny Car engines use forced induction.