Glossary of drag racing terms:

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.

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, "breakout" refers to a contestant running quicker than he or she "dialed" his or her vehicle (predicted how quick it would run). Unless the opponent commits a more serious foul (e.g., red-lights, crosses the centerline, or fails a post-race inspection), the driver who breaks out loses. If both drivers break out, the one who runs closest to his or her dial is the winner.

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 to heat and clean them prior to a run for better traction. A burnout precedes every run.

Christmas Tree:
Also called the Tree, it is the noticeable electronic starting device between the lanes on the starting line. It displays a calibrated-light countdown for each driver.

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 beams after staging, which causes the pre-stage lights to go out. In that position, a driver is closer to the finish line but dangerously close to a foul start.

Dial under:
When drivers in Super Stock and Stock (handicap categories) select an elapsed time quicker than the national index. Drivers select a dial-under, or e.t., that they think their cars will run based on previous performance. The breakout rule is in effect.

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.

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

Elapsed time:
The time it takes a vehicle to travel from the starting line to the finish line. Also called e.t.

Eliminations:
After qualifying, vehicles race two at a time, resulting in one winner from each pair. Winners continue in tournament-style competition until one remains.

Foul start:
Indicated by a red light on the Christmas Tree when a car has left the starting line before the green light, or starting signal.

Full Tree:
Used in Competition, Super Stock, and Stock, for which a handicap starting system is used to equalize competition. The three amber bulbs on the Christmas Tree flash consecutively five-tenths of a second apart, followed five-tenths later by the green starting light. A perfect reaction time on a full Tree is .500.

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.

Holeshot:
When a driver reacts quicker to the Christmas Tree to win a race against an opponent with a quicker e.t.

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:
The expected performance for vehicles in a class as assigned by NHRA. It allows various classes of cars in the same category to race together competitively.

Interval timers:
Part of a secondary timing system that records elapsed times, primarily for the racers' benefit, at 60, 330, 660, and 1,000 feet.

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

Nitromethane:
Produced specifically as a fuel for drag racing, it is the result of a chemical reaction between nitric acid and propane.

Pre-stage:
To position the front wheels about seven inches behind the starting line so the small yellow lights atop that driver's side of the Christmas Tree are glowing. The next step is to stage and be ready to race.

Pro Tree:
Used in Top Fuel, Funny Car, Pro Stock, Pro Stock Motorcycle, Top Alcohol Dragster, Top Alcohol Funny Car, Super Comp, Super Gas, and Super Street, which feature heads-up competition. All three large amber lights on the Christmas Tree flash simultaneously, followed four-tenths of a second later by the green starting light.

Reaction time:
The time it takes a driver to react to the green starting light on the Christmas Tree, measured in thousandths of a second. The reaction-time counter begins when the last amber light flashes on the Tree and stops when the vehicle clears the stage beam.

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 in most cases determines how quick the rest of the run will be.

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

Speed trap:
The final 66 feet to the finish line where speed is recorded.

Stage:
To position the front wheels right on the starting line so the small yellow lights below the pre-stage lights are glowing. Once both drivers are staged, the calibrated countdown (see Christmas Tree) may begin.

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

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

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.

What is E.T Bracket Racing?

By far the most popular form of drag racing is a handicapped form of competition known as E.T. bracket racing. In this form of racing, two vehicles of varying performance potentials can race on a potentially even basis. The anticipated elapsed times for each vehicle are compared, and the slower car receives a head start equal to the difference of the two. With this system, virtually any two vehicles can be paired in a competitive drag race.

For Example: Car A has been timed at 17.78, 17.74, and 17.76 seconds on the quarter-mile, and the driver feels that a dial-in of 17.75 is appropriate. Meanwhile, the driver of car B has recorded elapsed times of 15.27, 15.22, and 15.26 on the same track and has opted for a dial-in of 15.25. Accordingly, car A will get a 2.5-second head start against car B when the Christmas Tree counts down to each car's starting green lights.

If both vehicles cover the quarter-mile in exactly the predetermined elapsed time, the win will go to the driver who reacts quickest to the starting signal. That reaction to the starting signal is called reaction time. Both lanes are timed independently of one another, and the clock does not start until the vehicle actually moves. Because of this, a vehicle may sometimes appear to have a mathematical advantage in comparative elapsed times but actually lose the race. This fact makes starting-line reflexes extremely important in drag racing!

What is "Breakout" and/or "Red-light"?

After both cars are staged, the starter activates Christmas Tree, and three amber lights and one green are sequenced.    Racers use amber lights as a guide to anticipate the green bulb coming on. If they leave too soon, a bright red foul shows.What is "Breakout" and/or "Red-light"?
Should a racer go quicker than his or her predetermined dial-in, it is a breakout and grounds for disqualification. If both racers make runs under their dial-ins, the win goes to the racer who breaks out the least. Another form of disqualification is a foul start, or red light. This happens when the racer reacts to the Christmas Tree too quickly and leaves the starting line before the green go signal. When dual infractions occur (for example, a red-light and then a breakout), the red-light takes precedence over the breakout.