Water-Cooled VW Performance Handbook
Horsepower estimates from ¼-mile results
If you have access to a dragstrip and a vehicle scale, you can guestimate your engine horsepower — no dyno needed!
Using trap speed and weight
If you know how fast your vehicle is traveling at the end of a quarter-mile run, you can calculate an estimated horsepower. That is, on the basis of your final speed through the traps, you can guestimate your engine horsepower.
For example, a 2,400 pound vehicle with 300 horsepower should make it through the quarter-mile in 11.65 seconds, with a trap speed of 117 miles-per-hour.
This calculator uses the formula:
HP = (MPH ÷ 234)³ × Weight
Using ¼-mile time and weight
If you know how long it takes your vehicle to run a standing quarter-mile , you can calculate an estimated horsepower. That is, on the basis of your ¼-mile time, you can guestimate your engine horsepower.
For example, a 2,400 pound vehicle with a quarter-mile time of 11.65 seconds is making about 300 horsepower.
This calculator makes use of the formula:
Note: The results you obtain from these calculators are just guestimations, though. Front-wheel drive cars are different from rear-wheel drive cars, and all-wheel drive cars are different still.