Brake Horsepower

[ProShift]

I hear people talking about brake horse power is it different than the american horse power

this might be a stupid question but i have no clue hahah

[Alastor187]

From http://www.wordiq.com/definition/Horsepower

bhp

Brake horsepower was a term commonly used before the 1970s in the USA, and is still common in the UK. It indicates the brake*, the device for measuring the true power of the engine. Stating power in 'bhp' gives some indication this is a true reading, rather than a calculated or predicted one. However, several manufacturers started to strip their engines of essential ancilliaries for the purposes of getting a high horsepower figure to use in marketing the car.

In the USA the term fell into disuse after the American Society of Automotive Engineers (SAE) recommended manufacturers use "hp (SAE)" to indicate the power of the engine, given that particular car's complete engine installation. This may also be stated as "SAE net hp" or simply "net hp". The British market seemed not to need the correction.


From http://neptune.spacebears.com/opine/horsepwr.html

SAE Net Horspower

In 1972, American manufacturers phased in SAE net horsepower. This is the standard on which current American ratings are based. This rating is measured at the flywheel, on an engine dyno, but the engine is tested with all accessories installed, including a full exhaust system, all pumps, the alternator, the starter, and emissions controls. Both SAE net and SAE gross horsepower test procedures are documented in Society of Automotive Engineers standard J1349. Because SAE net is so common, this is the standard we will use to compare all others.


*Brake does not refer to the vehicles brakes or the wheels in anyway, it is the type of device that measures the engine output.

[pro_am]

I've always wondered that. Thanks for clarifying.
Jake

[ProShift]

hmmm sooo my car has 186 BHP ..... but i can say i just have 186 horspower then ???? kinda confused here

[Alastor187]

hmmm sooo my car has 186 BHP ..... but i can say i just have 186 horsepower then ???? kinda confused here

Yes, you could say your car has 186 HP and that would be good enough for most people. Basically BHP represents the useful horsepower that can be applied to the crank, and it is what most people are concerned with.

However, when BHP is measured there are many parasitic devices attached to the engine and each one uses a certain amount of horsepower. So if your car makes 186 BHP with the exhaust system, all pumps, the alternator, and etc., it would make more horsepower without those devices.

The horsepower of the motor alone without any parasitic devices is referred to as ‘SAE gross horsepower’ (in the US anyway). Because this number is always larger than BHP it may be nice for bragging rights, but that is about it. Engineers use gross horsepower for various calculations but for everyone else it doesn’t really give the most realistic idea of the engines capability.

[SaabJohan]

There are also imperial and metric definitions on what one horsepower is. The imperial system defines it with feet and pounds while the metric defines it with kg and meters. This causes a slight difference on what one hp is.