After every pass down a drag strip, you get a small printed receipt, or a text on your phone at newer tracks, full of numbers. That's the time slip. To a new racer it looks like a jumble of decimals. To an experienced one, it's a complete story of the run: how you left, how well the car hooked, where it pulled hard and where it didn't.
This article goes through a typical slip line by line and explains how to read the numbers together.
A sample time slip
Here's what a slip for one lane might look like for a mid-12-second street car. Layouts vary from track to track, but the lines are usually in this order, following the car down the track.
| Line | Value |
|---|---|
| Dial-in | 12.45 |
| R/T (reaction time) | .041 |
| 60' | 1.812 |
| 330' | 5.221 |
| 1/8 ET (660') | 7.998 |
| 1/8 MPH | 88.14 |
| 1000' | 10.380 |
| 1/4 ET (1320') | 12.474 |
| 1/4 MPH | 109.52 |
Every time on the slip, except R/T, is measured from the moment the car leaves the starting line. None of them include reaction time.
Reaction time (R/T)
How long after the green light your car cleared the stage beam. Lower is better, and a negative number means a red light. The reaction time article covers this in detail. The key point for reading a slip is that R/T is separate from ET. A great ET with a slow R/T can still lose.
60-foot time
The 60-foot time is how long the car took to cover the first 60 feet. It's the single most useful number for judging the launch, because almost nothing else affects it: not the top-end power, not the shifts into the higher gears, just how well the car left and how well the tires held.
Some rough reference points:
- 2.0 seconds or more: a typical street car on street tires, often with some wheelspin.
- 1.6 to 1.9: a well-driven car with decent tires and a good launch.
- Under 1.4: a serious race car with slicks and a prepared track.
A common rule of thumb is that every hundredth you take off the 60-foot takes somewhere around one and a half to two hundredths off the quarter-mile ET. The car carries that extra speed the rest of the way down the track. That's why racers obsess over launch technique, tire pressure and track prep. See Burnouts and Traction for more on that.
330-foot time
The time to 330 feet, a quarter of the way down. By now the car is usually through first gear and into second. Comparing the 60-foot and the 330-foot tells you whether the car kept pulling after the launch. A great 60-foot followed by a weak 330 often points to tire shake, a missed or slow shift, or the tires losing grip once the car's weight shifts.
Eighth-mile ET and MPH
The time and speed at 660 feet, the halfway point. Many tracks race the eighth mile only, so for some racers this is the finish line. On a quarter-mile pass it's a useful checkpoint, because it splits the run into a launch half and a power half.
The speed here, like the trap speed at the finish, isn't a single instant reading. It's an average over a short "speed trap" just before the mark, calculated from how long the car took to cross it.
1,000-foot time
Not every track reports this, but it's valuable. It's the time at 1,000 feet, which is also the finish line for the fastest professional classes. For a sportsman car, a big change in the gap between the 1,000-foot time and the quarter-mile ET usually means something happened at the top end, like a late shift, the engine hitting the rev limiter, or the driver lifting before the finish.
Quarter-mile ET
The elapsed time, from the moment the car left the starting line to the moment it crossed the finish line, 1,320 feet later. This is the number everyone quotes: "it runs 12.47." It's measured to the thousandth of a second.
ET is a mix of everything: the launch, the shifts, the power and the aerodynamics. On its own it tells you how good the run was. Paired with the other numbers, it tells you why.
Trap speed (MPH)
How fast the car was going as it crossed the finish line, averaged over the last stretch before the stripe. Trap speed mostly reflects power-to-weight. A launch problem costs you a lot of ET but only a little trap speed, because the car still makes its power once it's rolling.
That makes ET and MPH a useful pair:
| ET | MPH | Usually means |
|---|---|---|
| Slow | Normal | A launch or traction problem. The car made its power, but lost time early. Check the 60-foot. |
| Slow | Low | A power problem, a missed shift, or the driver lifting before the stripe. |
| Quick | Normal | A good pass. |
| Quick | High | A good pass in good conditions (cool, dry air). |
Our power-to-weight article has a calculator that estimates the trap speed and ET a car should run from its weight and horsepower, which is a good sanity check for your own numbers.
Dial-in and the win light
In bracket racing, each driver predicts their own ET before the run. That prediction, the dial-in, is printed on the slip. The slip also shows who won the round, and many tracks print the margin of victory as a time. If you ran quicker than your dial-in, that's a breakout, and in most cases it means you lost.
Weather and density altitude
Engines make more power in cool, dry, dense air. Many tracks print the temperature, humidity and barometric pressure on the slip, or a single number called density altitude. Racers who run the same car every week use it to explain why the car picked up or slowed down, and to predict what it will run next time.
Reading your slip in The Drag Car Racer
After each run, the simulator hands you a time slip laid out like the one above, for both lanes: R/T, 60-foot, 330-foot, eighth-mile ET and MPH, 1,000-foot, and quarter-mile ET and MPH, with trap speeds averaged over the last 66 feet like a real track's. The simulator has no weather, so changes in your numbers come down to your driving. A slow ET with a normal trap speed means you lost time at the start, so work on staging and the launch. A slow ET and low trap speed usually means a missed shift or riding the rev limiter. Your best ETs in each class go on the top-5 leaderboard.