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NHRA Glossary

Drag racing terms

TermDefinition

Air Box

   
Used primarily on Pro Stock Motorcycles, it settles "negative air" around carburetors the way a hood scoop does on a car.

Air Foil

   
The same as a wing — a stabilizer, generally used to create downforce, which increases stability and tire-to-track adherence at high speeds.

Backpedal

   
When a driver lets off the throttle to regain traction or to avoid or stop tire shake.

Bang the blower

   
An explosion inside the supercharger caused by a flame from the combustion process accidentally re-entering the supercharger, where fuel and air are present. Generally caused by a stuck or broken intake valve that normally would be closed during the combustion sequence.

Breakout

   
Used only in handicap racing. Refers to a vehicle running quicker than the racer has ­predicted, or “dialed.” The racer who breaks out loses unless his or her opponent breaks out by more or commits a more serious foul, such as leaving too soon (see “Foul Start”) or crossing the centerline.

Bump

   
The bottom spot in the field, usually the No. 16 qualifying position. Also called the “bubble.”

Bumped

   
When a racer is moved from a higher ­qualifying position to a lower one after another ­competitor improves.

Burned piston

   
When a cylinder runs lean (too much air in the air-to-fuel mixture) and excessive heat burns or melts the piston.

Burnout

   
Spinning the rear tires in water before a run to heat and clean them and put rubber on the track for better traction.

Christmas Tree

   
Also called the Tree, the ­electronic starting device between the lanes on the starting line.

Chute

   
Short for parachute, this device helps slow the car at the end of a run.

Clutch Can

   
The bell-shaped housing, or bellhousing, used to encase the clutch and flywheel.

Clutch Lockup

   
The progression of clutch-disc engagement controlled by an air-timer management system.

Deep Stage

   
To roll a few inches farther into the stage beam, indicated by the pre-stage lights on the Christmas Tree turning off. In that position, a racer is closer to the finish line and also closer to a foul start (red-light).

Dial-Under

   
Used in Super Stock and Stock, when a driver selects, or dials, an elapsed time quicker than the national index. Drivers select a dial-under, or e.t., that they think their car will run based on ­previous performance.

Diaper

   
An absorbent blanket made from ballistic material, often Kevlar, that surrounds the oil pan to contain oil and parts in case of an engine explosion; required for Top Fuel, Funny Car, Top Alcohol Dragster, and Top Alcohol Funny Car.

Digger

   
Another word for dragster.

DNQ

   
Did not qualify.

Dropped cylinder

   
When a cylinder runs too rich (too much fuel in the air/fuel mixture) and prevents the spark plug(s) from firing.

Dropped Cylinder

   
When a spark plug fails to ignite, ­substantially decreasing total power ­output by the engine. A dropped cylinder is often ­distinguishable by raw fuel spewing from an exhaust header.

Elapsed Time (e.t.)

   
The time it takes a vehicle to travel from the starting line to the finish line.

Eliminations

   
The portion of an event that ­determines a race winner, usually Sunday. Vehicles are raced two at a time, resulting in one winner and one loser. Winners continue to race in a tournament-style ­competition until only one remains.

Flopper

   
Another word for a Funny Car.

Foul Start

   
Also known as a red-light. When a vehicle leaves the starting line before the green light, ­indicated by the red light on the Tree. When a foul start occurs in eliminations, the racer is eliminated from further competition at the event (unless his or her opponent commits a worse infraction). A red-light in qualifying has no impact on the racer’s attempt; his or her time still counts toward qualifying for the event.

Full Tree

   
Used in Comp, Super Stock, Stock, Top ­Dragster, and Top Sportsman for which a ­handicap starting system equalizes competition. The three amber lights flash consecutively five-tenths of a second apart, followed five-tenths later by the green light.

Groove

   
Path of traction laid down by other ­vehicles that have gone down the racetrack; for example, “in the groove.”

Handicap

   
The head start given to the slower car in a race featuring two vehicles of varying performance potentials. Used in Comp, Super Stock, Stock, Top Dragster, and Top Sportsman.

Header(s)

   

A fine-tuned exhaust system that routes exhaust from the engine; replaces conventional exhaust manifolds

Hemi

   
A Hemi engine has a hemispherical shaped cylinder-head combustion chamber, like a ball cut in half

Hide

   
Tire; for example, “He was smokin’ the hides.”

Holeshot Win

   
When a racer with an e.t. slower than that of his or her opponent wins an ­eliminations round because he or she had a ­better reaction time, or left the starting line first.

Hydraulic

   
When a cylinder fills with too much fuel, thus prohibiting compression by the cylinder and causing a mechanical malfunction, usually an explosive one

Index

   
An e.t. assigned by NHRA as a predictor of performance for vehicles in that class. Indexes allow various classes of cars in the same ­eliminator to race competitively.

Interval Timers

   
Elapsed time clocks at 60, 330, 660, and 1,000 feet that record the e.t. from the starting line to those intervals.

Loose

   
When a car gets out of the groove; for example, “He got loose at about 60 feet.”

Loud Pedal

   
Gas pedal or throttle.

Methanol

   
Pure methyl alcohol produced by ­synthesis; used in some Top Alcohol Dragsters and all Top Alcohol Funny Cars.

Nitromethane

   
Known as “nitro,” CH3NO2 is the result of a chemical reaction between nitric acid and propane. Primary fuel for Top Fuel dragsters, Funny Cars, and injected nitro ­dragsters in Top Alcohol Dragster.

Oildown

   
When a race car deposits oil from the engine onto the racing surface, causing a delay.

On the Trailer

   
Where a race car is put after ­losing or not qualifying; for example, “He was on the trailer after round one.”

Pre-staged

   
When a racer is approximately 7 inches behind the starting line and the top half of the circle of small blue lights atop his or her side of the Christmas Tree is illuminated.

Pro Tree

   
Used in Top Fuel, Funny Car, Pro Stock, Pro Stock Motorcycle, Top Alcohol Dragster, Top Alcohol Funny Car, Super Comp, Super Gas, Super Street, and Pro Mod, all of which feature ­heads-up (no handicap) competition. The three large amber lights flash simultaneously, followed four-tenths of a second later by the green light.

Rail

   
Another name for a dragster.

Reaction Time

   
The time it takes for a vehicle’s front tires to clear the staging beam after the green light comes on; measured in fractions of a second. A perfect reaction time is .000.

Red-Light

   
See “Foul Start.”

Safety Safari®

   
A team of men and women responsible for transporting equipment from race to race, preparing and maintaining the racing surface, and providing support in an emergency. The NHRA Safety Safari is presented by AAA.

Sand Trap

   
Located beyond the shutdown area; used to help stop errant race cars.

Shoe

   
Driver.

Shutdown Area

   
Area past the finish line where race vehicles come to a stop and racers are picked up by their crews.

Sixty-Foot Time

   
The time it takes a vehicle to cover the first 60 feet of the racetrack. It is the most accurate measure of the launch from the starting line and is the interval most critical to a quick e.t.

Slick

   
Racing tire that does not have tread.

Slider clutch

   
A multi-disc clutch designed to slip until a predetermined rpm is reached; decreases shock load to the drive wheels.

Smoked the Tires

   
When a car loses traction; also “blew the tires off” or “hazed the tires.”

Speed Trap

   
The final 66 feet to the finish line where speed is calculated.

Staged

   
When the front wheel or wheels of the vehicle are on the starting line. Once the racer is staged, the calibrated countdown of the amber lights leading to the green starting light may begin anytime.

Stripe

   
Slang term for the finish line.

Supercharger

   
A crank-driven air/fuel-mixture compressor, also called a blower. It increases atmospheric pressure in the engine to produce more horsepower.

The Wally®

   
Official NHRA trophy.

Time Slip

   
Given to the racer or crew after a run, it lists the reaction time, interval times, elapsed time, and speed.

Tire Shake

   
A severe vibration that usually occurs at the beginning of the run and is the result of losing traction.

Treed

   
A racer whose reaction time is ­significantly slower than an opponent’s is said to have been Treed.

Turbocharger

   
An exhaust-driven intake air compressor (see supercharger).

Wally Parks

   
NHRA founder (1913-2007), for whom The Wally is named.

Wedge

   
An engine with a combustion chamber resembling a wedge in shape

Weight transfer

   
Critical to traction. Vehicles are set up to provide a desired weight transfer to the rear wheels. Upon acceleration, the front wheels lift and the weight shifts to the rear wheels, which makes them less likely to spin.

Wheelie bar(s)

   
Used to prevent excessive front-wheel lift.