Glossary
Drag Racing Glossary
Every term a racer reads on a time slip, defined.
Time slip basics
What is ET in drag racing?
ET stands for elapsed time — the seconds from when the front tire breaks the staging beam to when it crosses the finish line. A quarter-mile (1320 ft) ET of 10.50 seconds means the car covered the 1320 feet in 10.50 seconds. Lower ET is faster. Time slips always print ET to the thousandth (10.501).
ET (Elapsed Time) — also called: elapsed time, et, quarter-mile ET, eighth-mile ET
What is MPH on a drag racing time slip?
MPH on a time slip is the trap speed — the car’s speed averaged across the last 66 feet before the finish line. It’s a measure of horsepower per pound, not how fast you were going at the finish exactly. A 10.50 ET at 130 mph means more power than the same ET at 120 mph.
MPH (Trap Speed) — also called: mph, trap speed, finish line speed
What is reaction time in drag racing?
Reaction time is the seconds between the green light turning on and the front tire leaving the staging beam. A perfect reaction is 0.000 (Pro Tree) or 0.500 (Sportsman/Full Tree). Anything quicker is a red light — automatic disqualification. The number does not count toward your ET, but it decides who wins a close race.
Reaction Time — also called: RT, reaction, light
What is a 60-foot time?
The 60-foot time is how many seconds the car takes to cover the first 60 feet of the track from launch. It’s the single best indicator of launch quality and traction. A 1.40 sixty is street-tire fast; a 1.10 is full-prep slick territory. Quarter-mile ET typically tracks at roughly 60-foot × 7.5.
60-Foot Time — also called: 60ft, short time, launch time
What are 330, 660, and 1000 foot times?
Splits are checkpoints printed on every NHRA time slip: 330 feet, 660 feet (eighth-mile), 1000 feet, and 1320 feet (quarter-mile). Each is the elapsed time at that distance, plus an MPH at 660 and 1320. Splits show whether the car was strong early, late, or both — critical for diagnosing why an ET changed.
330 / 660 / 1000 Splits — also called: splits, 330ft, 660 foot, incremental times
Dial-in & bracket racing
What is a dial-in in bracket racing?
A dial-in is the ET you predict your car will run on the next pass. It’s written on the windshield or staged via control panel before the race. If you dial 10.50 and run 10.49, you "break out" (lose); 10.51 means you ran slower than your dial, which is legal but slow. The closer to your dial without going under, the better.
Dial-In — also called: dial, dial number, dial-in time
What does breakout mean in bracket racing?
Breakout is when your car runs a quicker ET than the dial-in you posted. In a heads-up bracket race, breaking out loses the round automatically — unless your opponent breaks out by more or red-lights first. Bracket racers chase the dial without going under, which is why ET prediction tools matter so much.
Breakout — also called: break out, going under your dial
What is bracket racing?
Bracket racing is handicap drag racing where each driver picks a dial-in time and the starting tree gives the slower car a head start equal to the difference in dials. Winner is whoever crosses the finish line first without leaving early (red light) or running quicker than their dial (breakout). It rewards consistency over raw power.
Bracket Racing — also called: bracket, handicap racing, index racing
What is a delay box in drag racing?
A delay box is an electronic device that holds the transbrake or starting solenoid for a set amount of time after the driver releases the button, so the car launches at a precise moment relative to the tree. It lets racers cut perfectly tuned reaction times. Legal in most bracket and super classes; banned in heads-up.
Delay Box — also called: delay, transbrake delay
What does deep stage mean?
Deep staging is rolling the front tire a few inches past the normal staging position so the pre-stage beam goes out. This shortens the rollout distance, makes the reaction time appear quicker, but trades a tiny amount of ET because the car has slightly less wheel-speed when it triggers the finish beam. Common in bracket racing.
Deep Stage — also called: deep staging
Weather & atmosphere
What is density altitude in drag racing?
Density altitude is the altitude your engine "feels" given the current air temperature, humidity, and barometric pressure. Hot, humid, low-pressure air at sea level can feel like 3000 ft of elevation to the engine. Higher DA = thinner air = less horsepower = slower ET. Every Drag Race Logbook Pro run records DA automatically.
Density Altitude — also called: DA, density alt
What is a correction factor in drag racing?
A correction factor is a number used to normalize your ET or MPH to a standard atmospheric baseline (typically 60 °F, 29.92 inHg, 0% humidity, sea level). Multiply actual ET by the CF to estimate what the car would have run at that standard. It’s how racers compare runs from different days or tracks.
Correction Factor — also called: weather correction, CF
How does barometric pressure affect drag racing?
Barometric pressure measures the weight of the column of air above the track. Higher pressure (closer to 30.00 inHg) means denser air, more oxygen in each combustion event, more horsepower, and a quicker ET. A 0.10 inHg drop in baro typically slows a quarter-mile car by 0.01–0.02 seconds.
Barometric Pressure — also called: baro, barometer, pressure
What is vapor pressure in drag racing?
Vapor pressure is the partial pressure of water in the air, measured in inches of mercury. Higher vapor pressure means more water displacing oxygen in each cylinder — less power, slower ET. Racers monitor it alongside DA because two days can have the same DA but very different vapor pressure and feel different.
Vapor Pressure — also called: water vapor pressure
What is air density in drag racing?
Air density is the mass of air in a given volume, usually expressed as a percentage of standard sea-level dry air (100% = 60 °F, 29.92 inHg, 0% humidity). 95% means thinner air, less oxygen per intake stroke, less power. It’s the same physical concept as density altitude, expressed differently.
Air Density — also called: relative air density, air density percent, AD
Lights, lanes & the tree
What is the Christmas tree in drag racing?
The Christmas tree is the column of starting lights at the line: two amber pre-stage and stage bulbs at the top, three or four amber countdown bulbs below, and a green at the bottom (red if you leave early). It controls launch timing and sets the handicap in bracket racing.
The Tree — also called: starting tree, christmas tree
What is the difference between a Pro Tree and a Sportsman Tree?
A Pro Tree flashes all three amber bulbs at once, then green 0.400 seconds later — perfect reaction is 0.000. A Sportsman (Full) Tree counts down the ambers one at a time 0.500 seconds apart, then green — perfect reaction is 0.500. Pro Tree is heads-up classes; Sportsman is bracket racing.
Pro Tree vs Sportsman Tree — also called: pro tree, sportsman tree, full tree
What is a red light in drag racing?
A red light means you broke the staging beam before the green came on — you "left too early." It’s an automatic loss in any race, regardless of who crossed the finish line first or what ETs were run. The reaction-time number printed will be negative (e.g. –0.012 = twelve thousandths too early).
Red Light — also called: red lighting, red
What are the staging beams?
The staging beams are infrared light beams across each lane near the starting line. The first beam (pre-stage) lights when the front tire enters; the second (stage) lights when the tire is at the launch point. Both must be lit for the tree to start. Rolling through the stage beam is what triggers reaction-time measurement.
Staging Beams — also called: pre-stage beam, stage beam, staging lights
What is rollout in drag racing?
Rollout is the small distance the front tire travels between unblocking the stage beam and triggering the timing system at full launch. Deep staging shortens rollout (quicker reaction, slightly slower ET). Tire diameter, suspension squat, and how shallow the car is staged all change rollout — and therefore your numbers.
Rollout — also called: stage rollout
Sanctioning & classes
What is the NHRA?
NHRA is the National Hot Rod Association, the largest drag racing sanctioning body in the world. It runs the professional Mission Foods NHRA Drag Racing Series plus sportsman and bracket programs at hundreds of member tracks. NHRA rules govern safety equipment, class definitions, timing system standards, and the licensing program.
NHRA — also called: national hot rod association
What is the IHRA?
IHRA is the International Hot Rod Association, the second-largest drag racing sanctioning body. It runs its own pro and sportsman classes (Top Dragster, Top Sportsman, Quick Rod) alongside bracket programs. Many tracks are dual-sanctioned NHRA + IHRA, so the same strip hosts events from both bodies.
IHRA — also called: international hot rod association
What are the Super classes in drag racing?
The Super classes are NHRA index classes where every car runs the same target ET: Super Comp at 8.90, Super Gas at 9.90, Super Street at 10.90 (all quarter-mile). Heads-up, no handicap. Run quicker than the index and you break out. They are heavily delay-box-driven sportsman classes.
Super Comp / Super Gas / Super Street — also called: super class, super comp, super gas, super street, index class
What is a junior dragster?
A junior dragster is a half-scale rear-engine dragster powered by a small Briggs & Stratton or comparable engine, raced on eighth-mile tracks. The NHRA Jr Drag Racing League runs three classes: 12.90 (8–9 yr), 8.90 (10–12), 7.90 (13–17). It’s the entry path most pro drivers came up through.
Junior Dragster — also called: jr dragster, junior drag racing league, jdrl
What are Top Dragster and Top Sportsman?
Top Dragster and Top Sportsman are NHRA/IHRA fast-bracket classes for dragsters and door cars, respectively, with dial-ins typically ranging from 5.70 to 7.70 quarter-mile. Cars are full race cars with delay boxes and pro-style components, but the format is still bracket: pick your dial, don’t go under it, don’t red light.
Top Dragster / Top Sportsman — also called: TD, TS, top dragster, top sportsman
Hardware & technique
What is a transbrake?
A transbrake is a solenoid-actuated valve inside an automatic transmission that locks first and reverse simultaneously, holding the car still against the converter. Press the button at full throttle, release to launch. It allows much higher launch RPMs than the brakes alone, which is why every bracket and pro-style sportsman car uses one.
Transbrake — also called: trans brake, transbrake button
What is a two-step?
A two-step is a secondary rev limiter wired to the transbrake or clutch switch that holds engine RPM at a programmed launch number. Release the button and the limit clears — engine pulls clean instantly. It’s how stick-shift and transbrake cars stage at a consistent, repeatable launch RPM (e.g. 4500 rpm) every pass.
Two-Step — also called: 2-step, launch rev limiter
What is a wheelie bar in drag racing?
A wheelie bar is a pair of arms extending rearward from the chassis with small wheels at the ends. It prevents the front wheels from lifting too high under launch — when the car wheelies, the bar wheels touch the track and limit the angle. Required on most fast doorslammers and dragsters for safety and ET consistency.
Wheelie Bar — also called: wheelie bars
What is a burnout in drag racing?
A burnout is spinning the rear tires in the water box ahead of the starting line to heat the slicks, clean them, and lay down a thin layer of rubber for traction. Bracket racers run short, low-temp burnouts to stay consistent; fast doorslammers do long high-temperature burnouts. Done wrong, it kills 60-foot times.
Burnout — also called: burnout, water box
Track distances
How long is a quarter-mile drag strip?
A quarter-mile drag strip is 1320 feet from the starting line to the finish line — 0.25 miles, or 402.34 meters. That’s the original NHRA standard distance and what most sportsman, bracket, and IHRA events still run. Time slips print both ET and MPH at the 1320 mark.
Quarter Mile (1320) — also called: 1/4 mile, 1320, quarter
How long is an eighth-mile drag strip?
An eighth-mile drag strip is 660 feet from start to finish — half a quarter-mile. Most junior dragster classes, many fast doorslammers, and small-town tracks race eighth-mile because it’s safer for high-horsepower cars (lower top speed) and shorter overall events. Every NHRA time slip prints the 660 split anyway.
Eighth Mile (660) — also called: 1/8 mile, 660, eighth
Why do Top Fuel and Funny Car race 1000 feet?
NHRA shortened the racing distance for Top Fuel and Funny Car from 1320 to 1000 feet in 2008 after a fatal accident, to reduce top speeds in the shutdown area. Sportsman and bracket classes still run the full 1320. Time slips for 1000-foot races show ET at the 1000 mark as the official result.
1000-Foot Racing — also called: 1000 ft, thousand foot
Logbook & data
What is a drag racing logbook?
A drag racing logbook is the record a racer keeps of every pass: ET, MPH, splits, reaction time, weather, dial-in, lane, and any tuning changes. Historically a paper book in the trailer; today, a digital logbook like Drag Race Logbook Pro that scans time slips, fetches weather, and predicts the next pass.
Logbook — also called: drag racing logbook, race log
What is a drag racing time slip?
A time slip is the printed receipt the timing system produces after every run, with reaction time, 60-foot, 330, 660 (ET + MPH), 1000, and quarter-mile (ET + MPH), plus dial-in and lane. Snapping a photo of it into Drag Race Logbook Pro auto-fills every field in seconds instead of typing them in.
Time Slip — also called: time slip, timeslip, ticket
What does PB mean in drag racing?
PB stands for personal best — the quickest ET and fastest MPH you’ve ever run with a given car. Tracked separately, since a strong tailwind day might set an ET PB without a matching MPH PB. Drag Race Logbook Pro flags each new PB automatically as you log runs.
PB (Personal Best) — also called: personal best, PB ET, PB MPH
Put the terminology to work.
Drag Race Logbook Pro records every term above automatically — ET, MPH, splits, dial-in, density altitude, reaction time — from a single time-slip photo.