The term BPH is an acronym, which is normally used to stand for 'Brake HorsePower'. It is sometimes also written as 'BHP Horsepower' or 'BHP break horsepower', although this is somewhat incorrect as the acronym is thereby duplicated.

The output of an engine depends on where it is measured and under what conditions. Consequently, there are a variety of terms (e.g. BHP, effective horsepower, wheel horsepower) to describe where the power is measured and under what conditions. In the case of BHP, the measurement is done at the crankshaft and excludes power consumption by certain elements (e.g. gearbox, differential, alternator, muffler, cooling system). For a list and explanation of the various types of horsepower and measurement points, see types of horsepower.

In the case of cars, the two most common points of power measurement are at the crankshaft (known as BHP) or at the wheels (known as Wheel HorsePower or WHP). As a rough indication, BHP is about 15% to 25% higher than WHP, due to the consumption of power by mechanical elements and accessories between the crankshaft and the wheels. Note that 15-25% is a typical range but depending on the configuration and use of the car, the actual figure can be even higher or lower than this.

BHP is also known as 'crankshaft horsepower' or 'net horsepower'. The term 'break horsepower' is based on a device called a 'brake', which is used to measure the rotational speed and torque of the crankshaft and thereby calculate the horsepower.

Alternative Meanings

The most common meaning of BHP is 'break horsepower', as described above. It is also used to stand for British HorsePower, which is another name for mechanical horsepower, as opposed to electrical or metric horsepower.

Another possible meaning of BHP is Boiler Horse Power, which is a measurement related to steam engines. With the replacement of steam engines by more modern engines, this term is now seldom used.

For a more detailed discussion of each of these terms, see types of horsepower.

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