Horsepower per Liter Calculator (Engine Specific Output)
Calculate an engine's specific output — horsepower per litre, kW per litre and PS (CV) per litre — from power and displacement in L, cc or cubic inches, plus power and displacement per cylinder.
How it works
specific output = power ÷ displacement · 1 kW = 1.341 hp · 1 PS (CV) = 0.98632 hp · 1 L = 1,000 cc = 61.02 cubic inches · power per cylinder = power ÷ cylinders
Specific output (power per litre) shows how hard an engine works its displacement and is a quick way to compare engines of different sizes. Naturally aspirated road engines usually make 60–100 hp per litre, high-revving sports engines and modern turbocharged engines 100–160 hp/L, and race or heavily tuned engines more. A high figure usually comes from turbocharging, high rpm or both, and does not by itself mean an engine is better — big low-stressed engines often give more torque and longevity.
Worked example
A 2.0-litre four-cylinder turbo engine making 250 hp: 250 ÷ 2.0 = 125.0 hp per litre, or 93.2 kW/L and 126.7 PS/L. Each cylinder displaces 500 cc and makes 62.5 hp — a high-output turbocharged engine.
Sources: Engine power — specific output (power per displacement) · NIST SP 811 — Guide for the use of the SI: horsepower and metric horsepower conversion factors
Frequently asked questions
How do you calculate horsepower per liter?
Divide the engine's power by its displacement in litres. 300 hp from a 3.0 L engine is 100 hp per litre. Convert cc by dividing by 1,000 and cubic inches by multiplying by 0.01639.
What is a good horsepower per liter?
Around 70–100 hp/L is typical for modern naturally aspirated engines, 100–160 hp/L for performance turbo engines, and well above 150 hp/L for race engines. Older and truck engines are often under 60 hp/L.
What is the difference between hp, PS and CV?
hp (mechanical horsepower) is 745.7 W. PS (German Pferdestärke) and CV (French and Spanish caballo de vapor) are metric horsepower of 735.5 W, so 100 PS = 98.6 hp.
Is higher specific output always better?
Not necessarily. It shows efficiency of displacement, not torque, fuel economy or durability. A large, lightly stressed engine can make similar power with less boost and lower rpm.
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This calculator is for educational purposes. Double-check important results before acting on them.