Bhp

[zeiss150]

Hey Z people,

This is a lame question... but here it is anyway. Is blown Horse Power messured at the rear wheels, or is it messured at the flywheel? Thats, it...

Good times, Matt -

[Gav240z]

Well first off I think BHP stands for Brake Horse Power.

Most (if not all) manufacturers measure horse power at the flywheel.

Back before the government put a regulation in place manufacturers could measure horse power of a motor with all accessories off and in a controlled atmosphere ie: to read highest output so the US government instroduced a law stating they had to give a more accurate reading and therefore BHP was introduced.

[Alfadog]

And then we had SAE NET HP instead of gross HP and then decided to go to kW cos it was better! Or something! I dont really know!

[sblake01]

I don't see the 'kw' thing much over here and I'm still trying to figure out how it works. I've used conversion tables to convert kw to hp and vice versa but that still doesn't tell me anything different.

[Gav240z]

Kilowatts or KW is the metric unit or something similar i believe you would take say 150HP and divide by 1.3 to give you a KW rating.

[TomoHawk]

All I know is there are 746 watts per horsepower.

150 HP x 746 Watts /1000=112 kW

[mdbrandy]

Horsepower and KW are both just units of power, and mean the same thing. Power is a measure of energy per unit time - a kilowatt is 1000 Joules per second. A joule is a measure of energy. I'm not sure what the english units are that go into making up a horsepower, but it's the same idea, some unit of energy per some unit of time.

I think the main question for an engine is, where is that energy per unit time available - there are losses through the transmission and differential, so that there is less energy available at the rear wheels than there is at the flywheel.

[zeiss150]

Thanks for the info guy's

If it's Break horse power, Where did I get Blown horse power? I talked with my local nissan dealer and I asked them if the horse power rating of 287 for the 2004 350Z was messured at the flywheel or the rear wheels and they assured me that it was messured at the rear wheel. But for some reason I dont belive them. Am I to sinical? I drove the car and it didn't feel like it had any where near that amout of HP. My 240 Z with L24 seemed to pull harder. Is there more torque in the L24 than the 3.5 v6? and just to be extra clear ... BHP is messured at the flywheel... right?

Matt-

[mdbrandy]

After a little googling, I found the following at http://www.corridor-o.com/html/kids/html/horses.html:

The good old days

Up until 1971, engines were listed with what is called brake horsepower (Bhp) Brake horsepower is a calculation where the engine horsepower is measured at the point of output, with no load from a chassis or any accessories and with fuel and ignition operations under ideal conditions. Brake horsepower is often called gross horsepower today. This figure was often used for advertising purposes up to 1971.

An accessory is anything attached to the engine, by any means, which is not required for basic engine operation. By this definition, this would include a power steering pump, smog pump, air conditioning compressor and an alternator.

Ideal conditions, often called laboratory conditions, are standardized settings for use during horsepower measurement. During the 1960s they were a barometric pressure of 29.92 Hg and a temperature of 60 degrees F.

Today

Net horsepower, also called road horsepower, (Rhp) is a calculation where horsepower is measured after the load from a chassis and accessories. Essentially, this is the power available at the drive wheel or wheels of a vehicle. Nowadays called SAE net horsepower, it is the only method used for advertising purposes since 1972.

[TomoHawk]

Originally posted by zeiss150 Where did I get Blown horse power?....

You musta got that from some "expert". IHP is Injected HP? CHP is Carbed HP? THP is Turbo HP?

... nissan dealer assured me that the horse power rating of 287 for the 2004 350Z was messured at the rear wheel. But for some reason I don't believe him.

What!!?? Do you actually think that he doesn't know the REAL facts?? Like he's going to tell you something wrong to turn you off from buying a car? Of COURSE he'll tell you what you WANT to hear! Of course, you will have to buy the BHP (Big Horsepower) accesories! 110 octane gas for 30 more HP too!

Your dealer is also the MOST KNOWLEDGEABLE car expert in the area! He knows your car and every other car better than you or the engineers do!

They ARE good at B.S-ing tho. I hope no car salesmen are here....

[TomoHawk]

Do you know how "BHP" horsepower is measured?

If I remember right, you run the engine way up in RPM, then find out how much force it takes to stop (stall) the engine)

Something like that. See if your dealer knows that?

Maybe I'll go talk to my local dealer... I love to dress in a sport jacket, then go to a luxury dealer and tell him I wanna buy a car for my mom....

[mdbrandy]

Originally posted by TomoHawk

Do you know how "BHP" horsepower is measured?

Several of the other google'd web sites I was looking at defined BHP as being measured with a friction brake - thus a known force applied to the brake with a known coefficient of friction should be able to measure the energy it takes to stall the engine. Don't know the details of it though.