hp and bhp?

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Tue 27 Mar 2001 21:27
hp and bhp? - greg


what is hp and bhp mean--confused
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Tue 27 Mar 2001 22:05
Re: hp and bhp? - honestjohn
IT'S EXPLAINED IN ONE OF THE DE-MYSTIFIED MOTORS IN THE DAILY TELEGRAPH BOOK OF MOTORING ANSWERS 2000-2001.

HJ
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Tue 27 Mar 2001 22:54
Re: hp and bhp? - Peter B Karadakov
BHP (Brake Horse Power) or HP (Horse Power) is an imperial measure of power defined as 33,000 foot*pound/min, or 550 foot*pound/sec. The equivalent in metric units is 76.0402 kg*metres/sec.

The "metric" or continental measure of horse power known as PS (PferdeStarke) in german or CV (Cheval Vapeur) in french is a slightly different measure defined as 75 kg*metres/sec. One PS is therefore slightly smaller than one BHP, 1 PS = 0.98632 BHP.

Useful additional conversion factors: 1 KW = 1.341 BHP = 1.360 PS.

There appears to be a lot of confusion related to the use of the different power units. For example, the BHP and PS figures reported for different VW models here and in Germany appear to be exactly identical. On the other hand, the continental Honda PS figures are multiplied by the PS to BHP conversion factor when listed in UK motoring magazines (e.g. 110 PS becomes 108 BHP). It is probably safer to look for and trust the KW figures.
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Thu 29 Mar 2001 14:41
Re: hp and bhp? - John Slaughter
The other thing to watch here is that power outputs can be measured in different ways. They are usually measured in a test rig, not in the car. Modern cars will be measured to an (I think) ISO standard, which at least means that they are reasonably comparable and bear some resemblance to what you'll get in the car as they will have things like alternators attached.

Going back a number of years each car maker did their own tests and there was less commonality of standards, so beware of comparing older cars with modern vehicles. These older data are probably less realistic than today, the classic being the American SAE standard, also used in the UK. This used a bare engine, no accessories, and allowed tweaking of the carburation at each measurement point. Result - apparently excellent power outputs which could be used for advertising, but which bore little resemblance to real life.

At the other extreme, there seem to be indications that the makers of the hotter Japanese cars and motorcycles may be underestimating power outputs. There are pressures on the makers to restrict the power outputs of the vehicles, and they may be doing it on paper at least.

Regards

john
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Thu 29 Mar 2001 21:45
Re: hp and bhp? - greg
hi,
thank's pete and john for explaining this--it has been extremely helpful---greg
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