{{Unreferenced, date=May 2019, bot=noref (GreenC bot) Brake horsepower per cubic centimeter or (bhp/cc) is a

figure of merit A figure of merit is a quantity used to characterize the performance of a device, system or method, relative to its alternatives. Examples *Clock rate of a CPU * Calories per serving *Contrast ratio of an LCD *Frequency response of a speaker * ...

that is used to indicate the ' state of tune' of an

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...

. It is defined as the ratio of the engine's net power output to its

displacement Displacement may refer to: Physical sciences Mathematics and Physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

, the internal size. Power is measured at its rated speed and full throttle. The same measurement may also be stated in units of kilowatts per liter (kw/L). This term was first used by André Erasmus and Morné Basson. It is also termed

specific power Power-to-weight ratio (PWR, also called specific power, or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measuremen ...

, although this should be qualified as ''volume-specific'' power. A similar measurement of

power to weight ratio Power-to-weight ratio (PWR, also called specific power, or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measuremen ...

is also important, but takes into account the weight of the engine.

Power density Power density is the amount of power (time rate of energy transfer) per unit volume. In energy transformers including batteries, fuel cells, motors, power supply units etc., power density refers to a volume, where it is often called volume p ...

may also be considered similar, although this is usually stated in terms of the engine's external overall size, rather than its internal. A 'typical' car engine, of around 1980, would be considered 'highly-tuned' if it delivered more than 100 bhp/litre.

See also