Trap Speed

There are two simple horsepower formulas that can estimate the on-the-pavement horsepower for a given car.

The ET method

This method uses the weight of the car and the time it took that car to travel 1330 feet (¼ mile).

The formula is: hp = weight / (ET / 5.825)3

The Trap-speed method

This method uses the weight of the car and the speed at which the car completed the quarter-mile run.

The formula is: hp = weight * (speed / 234)3

or speed = (cube root of (hp / weight)) * 234

Example

cbr ( 585 hp / 3400 lbs) * 234 = 130mph

Here is a cube root calculator. I know, there's never one around when you need one.