HP from 1/4-Mile Trap Speed

Estimate crank horsepower from your quarter-mile trap speed and weight.

How it works

1

Get your trap speed

The speed at the end of the quarter mile, in mph (the most power-dependent number on a time slip).

2

Enter weight

Race weight including driver, in kg or lb.

3

Read the estimate

Trap speed reflects power-to-weight well, so it gives a solid crank-HP estimate.

Frequently asked questions

How do you estimate HP from trap speed?

With the Hale formula: HP = weight_lb x (trap_mph / 234)^3. Trap speed depends mostly on power-to-weight and is far less affected by traction than the ET, which is why it gives a reliable horsepower estimate.

Why use trap speed and not the ET?

The 60-foot and ET are heavily affected by launch and traction; trap speed mainly reflects how much power moved the weight down the strip, so it is the better number for estimating engine output.

Is it crank or wheel HP?

The Hale formula returns approximate crank/flywheel horsepower for a typical car. Real figures vary with aero and conditions, so treat it as an estimate.

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