Glossary

Christmas Tree (Tree)

The electronic starting system positioned between the lanes at the starting line. It runs the light sequence that signals when each driver should launch.

Pre-stage

The first step in lining up: the front tires are positioned roughly seven inches behind the starting line so the small yellow pre-stage bulbs on that side of the Tree illuminate.

Stage

The next step after pre-stage: the front tires roll forward to the starting line until the stage bulbs light. Once both lanes are staged, the start sequence can begin.

Deep stage

Rolling a few inches farther forward after staging so the pre-stage lights go out. This can slightly shorten the distance to the finish line, but it also leaves the driver very close to a foul start.

Foul start

Leaving the starting line before the green signal. A foul start is shown by the red light on the Tree.

Reaction time

How quickly the driver responds to the start signal, measured in thousandths of a second. The timer starts when the last amber light activates and stops when the vehicle breaks the stage beam.

Full Tree

A handicap-style Tree used in Competition, Super Stock, and Stock. The three ambers flash one after another, each five-tenths of a second apart, and then the green light comes on five-tenths later. A perfect reaction time is .500.

Pro Tree

A heads-up Tree used in classes like Top Fuel, Funny Car, Pro Stock, Pro Stock Motorcycle, Top Alcohol Dragster/Funny Car, Super Comp, Super Gas, and Super Street. All three large ambers flash at once, then the green follows four-tenths of a second later.

Burnout

Spinning the rear tires (typically in the water box) to clean and heat them before a pass, improving traction. This is done prior to each run.

Sixty-foot time

The time it takes to travel the first 60 feet of the track. Its one of the best indicators of launch quality and often predicts how strong the rest of the run will be.

Elapsed time (E.T.)

The total time required for a vehicle to go from the starting line to the finish line.

Speed trap

The last 66 feet before the finish line where the vehicles speed is measured.

Interval timers

A secondary timing system that provides incremental elapsed times for racers, commonly at 60, 330, 660, and 1,000 feet.

Holeshot

Winning a race by reacting quicker at the start, even if the opponent runs a faster E.T.

Breakout

In handicap racing, running quicker than the dial-in (the predicted time). Unless the other driver commits a worse infraction (such as a red-light, crossing the centerline, or failing post-race inspection), the breakout driver loses. If both drivers break out, the win goes to the driver who is closest to their dial-in.

Eliminations

The post-qualifying rounds where cars race in pairs and the winner advances in bracket-style progression until a final winner remains.

Index

The performance target assigned by NHRA for a class. It helps different cars within a category compete on a more equal basis.

Dropped cylinder

When a cylinder becomes overly rich (too much fuel in the mixture) and the spark plug(s) fail to fire, reducing power.

Methanol

Pure methyl alcohol fuel used in Top Alcohol Dragsters and Top Alcohol Funny Cars.

Nitromethane

A drag racing fuel created through a chemical reaction involving nitric acid and propane.

Supercharger (blower)

A crank-driven compressor that forces more air/fuel mixture into the engine, increasing pressure and horsepower.

Turbocharger

An exhaust-driven compressor that pressurizes intake air (similar purpose to a supercharger, but powered by exhaust flow).

Wheelie bar(s)

Rear-mounted bars designed to limit excessive front-end lift during launch.