What’s the difference between hp and bhp?

By Product Expert | Posted in FAQs, Performance & Efficiency, Tips and Info on Wednesday, January 13th, 2021 at 10:32 pm
Silhouette of horse and rider on sunset

The power output capabilities of an engine are commonly represented through a type of measurement known as “horsepower,” often abbreviated as “hp.” However, you may also come across a figure denoted as “bhp;” this number tends to be different from the horsepower number. What is bhp, and how does it differ from hp?

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Horsepower Vs. Brake Horsepower

Horsepower and brake horsepower are both intended to measure the power of an engine. However, the way in which the figures are calculated is different, and this results in differing numbers. An engine is measured for horsepower with some pieces of the system missing, while brake horsepower is measured with every component in place. As a result, brake horsepower measurements include more frictional losses, which results in a lower figure.

Bhp appears to be the figure usually calculated and used in Europe, while hp is used in the United States.

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How is horsepower and brake horsepower measured?

Horsepower is measured using a tool called a simple dynamometer, while bhp uses a brake type dynamometer. A dynamometer is a type of mechanical brake that applies variable loads to a running engine; it’s designed to create a load duplicate to various speed and torque requirements. From this data, horsepower can be calculated.

Did you know?

One horsepower equals 33,000 foot-pounds of work per minute. The equation to calculate horsepower is: Horsepower = Torque x RPM / 5,252

Confusion Surrounding Bhp and Hp

It’s worth noting that the above conclusion is compiled from the best information we could track down. Other sources give alternative definitions, with some stating that hp has losses subtracted from it and is typically less than bhp.

One source cites horsepower as the output of a mechanical or electrical system, while the brake horsepower is the output of only the engine (the exact opposite of what we state above). In this definition, hp determines the efficiency of an entire system, while bhp is just for the engine.

In addition, there’s a type of measurement called wheel horsepower that individuals often use interchangeably with bhp. As you may imagine, this merely adds to the confusion.

So, let this be a reminder to resist the allure of certainty and embrace the ambiguity at the heart of our existence.

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