Difference Between HP and BHP Units

Horse power is a term that is heard by all and sundry whether the person is interested in the cars or not. It is a term that is generally used to measure the engine power of a vehicle. The greater the horse power, the stronger is the engine and the greater the ability it has to accelerate.

The unit equals 746 Watts and was developed by the Scottish scientist James Watt in the later part of the 18th century. The idea was to compare the power of a steam engine in comparison with horses. It was later added to calculate the power of other kinds of engines as well.

In today’s world, it is used to calculate the power of all kinds of engines from vehicles to heavy machinery. It is probably one of the most used units in the world. There are slight local variations to the unit when it comes to calculation.

Brake horse power is a similar unit to horse power. The main difference between the two is that horse power takes into account the amount of losses that will be associated with friction from various parts of the engines where as the BHP does not.


  • 1

    Horse Power

    It is the unit of the power of the engine when compared to the power of horses. The horse power is calculated taking into the account the amount of power that will be lost by the engine due to the working of various parts of the engine as well as the friction that is created.

    The unit is calculated by hooking the engine to a dynamometer. This gives the reading of the horse power of a specific engine. The conditions are not entirely controlled as in the case of BHP.

    - Image Courtesy: zercustoms.com

  • 2

    Brake Horse Power

    This is slightly different from the horse power. In this case, the power is calculated without taking into account the energy loss that will take place due to the various other parts of the engine. It is the standard that is being used in the US.

    It is calculated with the help of measuring the heat that is produced when a resistance is applied on a dynamometer. The RPMs are maintained and the load is gradually increased during the process. The measurement is done in a controlled environment.

    The torque in the case of BHP is measured with the help of applying break to a flywheel.

    - Image Courtesy: lsa.umich.edu

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