Motorvermogen calculator
The detailed guide below is currently available in English.
Two runs, two views of the same power
The trap-speed method cubes the finish-line speed, so it responds to the power that actually accelerated the car at the end of the quarter mile — traction early in the run barely moves it. The elapsed-time method divides weight by the cube of the run time and is sensitive to the whole run, including the launch. Enthusiasts run both numbers: matching estimates mean an honest pass, while a fast ET with a low trap speed usually points to tire or launch help rather than extra power.
Why weight dominates
Both formulas scale linearly with weight: carrying 400 extra pounds costs roughly 12% of effective power, the same as detuning a 300 hp engine to 264. That is why strip racers remove spare tires and sound deadening before touching the engine — and why the same car feels dramatically quicker with a passenger removed. Use curb weight plus the driver, fuel, and anything else along for the run.
Veelgestelde vragen
Does this give crank or wheel horsepower?
Neither exactly — it estimates the power that reached the pavement. Subtract roughly 10–15% drivetrain loss to approximate flywheel figures, so a 250 hp-at-the-wheels car suggests about 280–290 at the crank.
Why do my ET and trap speed give different answers?
Elapsed time rewards launch skill and grip while trap speed barely notices them. A mismatch usually means poor traction, a slow shift, or a tailwind — not that the formulas disagree.
Can I use it for the eighth mile?
Not directly. The 5.825 constant is specific to the quarter mile. Eighth-mile runs use different constants, so convert with a quarter-mile ET estimator first.