BHP - Knowledge is king.

[MK4 Slowride]

Brake horse power, I've been under the impression that this is the time it take for a horse to pull a hundred weight up a well. So my question is, A) How deep is the well? B) What is the time frame in which to execute this?

[AL666]

A hundred weight of what?

[MitchT]

Why is it called 'brake horsepower' anyway? Why not just 'horsepower'? What does the word 'brake' designate?

[r5gttgaz]

Its a pit pony pulling 33000lbs at a rate of 1ft / min.

[MK4 Slowride]

Horses were also used to stop heavy things like boulders from rolling down hills etc, i think that's where the brake bit comes from.

[mackie1]

http://en.wikipedia.org/wiki/Horsepow

Wikipedia said:

Brake horsepower (bhp) is the measure of an engine's horsepower without the loss in power caused by the gearbox, generator, differential, water pump and other auxiliaries. Thus the prefix "brake" refers to where the power is measured: at the engine's output shaft, as on an engine dynamometer. The actual horsepower delivered to the driving wheels is less. An engine would have to be retested to obtain a rating in another system. The term "brake" refers to the original use of a band brake to measure torque during the test (which is multiplied by the engine RPM and a scaling constant to give horsepower).

Dunno how correct that is but hey

Edited by mackie1 on Wednesday 7th February 18:16

[MK4 Slowride]

I'm at work and have anything remotely interesting (other than cars) blocked. please paste on to reply. Ta.

[r5gttgaz]

r5gttgaz said:

Its a pit pony pulling 33000lbs at a rate of 1ft / min.

[srebbe64]

MitchT said:

Why is it called 'brake horsepower' anyway? Why not just 'horsepower'? What does the word 'brake' designate?

Well didn't you know? It's "the power needed to break a horse". This is the reason that TVR used to quote high BHP figures, because they found the weakest point on the horse (the top of the ear) and broke it with the the engine.

Edited by srebbe64 on Wednesday 7th February 18:16

[w00dy]

the brake part comes from where the horsepower is measured on a car engine; at the engine brake, or as it's more commonly known, flywheel. Thus, this is the power after the drain of accessories.

[Sam_68]

srebbe64 said:

MitchT said:

Why is it called 'brake horsepower' anyway? Why not just 'horsepower'? What does the word 'brake' designate?

Well didn't you know? It's "the power needed to break a horse". This is the reason that TVR used to quote high BHP figures, because they found the weakest point on the horse (the top of the ear) and broke it with the the engine.

It's called Brake Horse Power because it's measured against an engine brake... ie. something that resists the engine turning and measures the amount or resistance to establish the amount of work being done.

And TVR didn't measure their engines against horses, nor even pit ponies (all the pits were in Wales and Yorkshire). The only available benchmark in Blackpool was a 23-year-old donkey on the beach.

[drags06]

r5gttgaz said:

Its a pit pony pulling 33000lbs at a rate of 1ft / min.

[TallMark]

I always thought the "brake" part referred to the fact that the power created was controllable.

Unlike say a jet engine where the power is relatvely uncontrollable.

Anyone else heard that one?

[drags06]

So what will a top fuel dragster lump make in TOTAL HP if it makes 8oooBHP and takes 35% just to drive the supercharger alone?

[Time Machine]

BHP is an attempt to provide a standard for comparisons of engines alone (if tested at S.T.P.). Al figures bandied around for Top Fuel Dragster are a bit approximate anyway as dynos which can accurately measure that level of power output have traditionally been hard to come by.

I have seen the stated power output of a Top Fueller go from 3,000 bhp to 10,000 bhp in my lifetime, and some people have tried to derive an accurate value with all sorts of calculations. All I know is that they are damn powerful beasts :-)

Even a blown alky V8 makes a whole load of power, I was interested to read in an interview with Freddy Fagerstorm of Pro Mod pickup fame that the aerodynamic inefficiency of a 1966 Chevy pickup means that however much power he throws down he can't break 220mph - the air resistance at that speed is such that when he tries to put the power down it'll smoke the tires. At over 200mph. That is a fair amount of power!

Edited by Time Machine on Wednesday 7th February 19:45

[slinky]

drags06 said:

So what will a top fuel dragster lump make in TOTAL HP if it makes 8oooBHP and takes 35% just to drive the supercharger alone?

8000hp..

The 35% is parasitic loss in driving the supercharger... if it were 100% efficient, you could add 35% of the power back on top to give you 10800hp..

[drags06]

So its all to do with maths estimates and conditions! Sort of clears it up a bit! Thanks guys Doe's this help Phil?

Edited by drags06 on Wednesday 7th February 20:44

[slinky]

Time Machine said:

I was interested to read in an interview with Freddy Fagerstorm of Pro Mod pickup fame that the aerodynamic inefficiency of a 1966 Chevy pickup means that however much power he throws down he can't break 220mph - the air resistance at that speed is such that when he tries to put the power down it'll smoke the tires. At over 200mph. That is a fair amount of power!

A very interesting interview.. would love to go to the pub with Freddy... and a translator!

[cyberface]

To the guys who reckoned that 'brake horse power' has to do with the amount of power required to break a horse, I'm sorry but you're utterly wrong. You appear to have got the words 'break' and 'brake' mixed up - for your theories to be plausible the measure would have to be called 'break horse power'. So there.

In fact, the 'brake' refers to brakes i.e. systems that slow down. Brake horse power is therefore the power required to slow down a horse from its terminal velocity when attached to the engine in question. Therefore you can attach an engine (without ancillaries, if you're american, but with all ancillaries except the exhaust pipe if you're european - the exhaust pipe can cause anomalous readings with terminal velocity due to air resistance) to a horse of standard weight and size, drop under standard gravity until it reaches terminal velocity, and then measure the braking power required to stop the horse.

This is still flawed as many point out, since the 'standard horse' is still variable, with those from Blackpool supposedly the Homo Floresiensis of horses, whereas those from Pfaffenhausen tend towards gigantism.

Hic.

[slinky]

cyberface said:

To the guys who reckoned that 'brake horse power' has to do with the amount of power required to break a horse, I'm sorry but you're utterly wrong. You appear to have got the words 'break' and 'brake' mixed up - for your theories to be plausible the measure would have to be called 'break horse power'. So there.

In fact, the 'brake' refers to brakes i.e. systems that slow down. Brake horse power is therefore the power required to slow down a horse from its terminal velocity when attached to the engine in question. Therefore you can attach an engine (without ancillaries, if you're american, but with all ancillaries except the exhaust pipe if you're european - the exhaust pipe can cause anomalous readings with terminal velocity due to air resistance) to a horse of standard weight and size, drop under standard gravity until it reaches terminal velocity, and then measure the braking power required to stop the horse.

This is still flawed as many point out, since the 'standard horse' is still variable, with those from Blackpool supposedly the Homo Floresiensis of horses, whereas those from Pfaffenhausen tend towards gigantism.

Hic.

Good work fella..