Engine CC to HP Converter

1. 1Enter the engine size in cc, litres or cubic inches.
2. 2Choose the kind of engine, such as a turbocharged petrol car or a sport motorcycle.
3. 3Read the exact size conversions and the estimated power range.
4. 4Or enter a known power figure to convert between horsepower, metric PS and kilowatts.

Displacement conversions are exact. One litre is 1,000 cubic centimetres and one cubic inch is exactly 16.387064 cc, so a 1,998 cc engine is 2.0 litres or 121.9 cubic inches.

Horsepower cannot be converted from cc, because displacement is only one ingredient of power. Two engines of the same size can differ several times over depending on turbocharging, how fast they rev and what they are tuned for. What can be done is an estimate from typical specific output — power per litre — for each kind of engine, shown as a low, typical and high figure.

The specific outputs used are: small scooter and commuter motorcycle engines about 60–95 hp per litre; naturally aspirated petrol car engines 70–110; turbocharged petrol engines 100–160; turbodiesel car engines 55–100; high-revving sport motorcycles 150–220; and large truck diesels 25–40. For a real engine, the manufacturer's rated figure is always the one to use.

Power units are converted exactly: one mechanical horsepower is 745.7 watts and one metric horsepower (PS, used on many European and Japanese specification sheets) is 735.5 watts, so 100 PS is 98.6 hp or 73.5 kW.

A 1,500 cc turbocharged petrol car engine

1. Enter 1500 cc and choose Petrol car, turbocharged.
2. 1500 ÷ 1000 = 1.5 litres, and 1500 ÷ 16.387064 = 91.5 cubic inches.
3. 1.5 litres × 100 to 160 hp per litre, with 120 as the typical figure.

Result: 1.5 L or 91.5 cu in, with an estimated 150–240 hp and typically around 180 hp.