justyourcalculatorEngine Horsepower Calculator
Estimate your engine's horsepower from a drag strip time slip.
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Engine Horsepower Calculator
Engine hp from quarter-mile ET or trap speed
Estimated horsepower
343 hp
255.9 kW at the wheels (approx.)
- Expected trap speed182.8 km/h
- 113.6 mph
- Power-to-weight
- 8.74 lb per hp
Quarter-mile formulas (Hale) give a rough estimate of power at the wheels. Traction, gearing and launch technique affect ET a lot, so trap speed is usually the better guide.
How it was calculated
- hp = weight ÷ (ET ÷ 5.825)³ = 3,000 ÷ (12 ÷ 5.825)³ = 343.1
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How the engine horsepower calculator works
The ET method uses the Hale formula hp = weight ÷ (ET ÷ 5.825)³, where weight is the car plus driver in pounds and ET the quarter-mile time in seconds.
The trap speed method uses hp = weight × (speed ÷ 234)³, with the speed in mph at the finish line. Trap speed depends less on traction and launch, so it usually gives the steadier estimate.
Both estimate power reaching the wheels. Engines are rated at the crank, which is higher by the drivetrain loss (often 10 to 20%).
Using and checking your result
Published by JustYourCalculator. Check the units and assumptions above, and compare a known example before relying on the output. Calculations use browser arithmetic and may round displayed values.
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