Nuke

SXGT, seems to me that you confuse terms. There is no term "real" power. It's either crank or wheels since those are the 2 places where HP/torque are measured. I suppose you can say that BOTH are "real".

JIM5.0

I would say that the wheel HP is the "real" BHP.
For example (this is an extreme example), it really does not matter if you get 1000 crank HP if lose 700 HP in the drivetrain and only get 300 HP at the wheels.
You butt dyno will only feel the 300 wheel BHP even though the engine is literally twisting the drive shaft like a string of lickerish candy.

HaHa, I always thought the acronym "RWHP" meant "Real World HP" instead of rear wheel HP.

VistaBlue

Jim,

BHP means brake horsepower, which is actually the more 'European' way of saying crank horsepower. Saying 300 wheel BHP is redundant; You would say 300rwhp, 300whp, 300 wheel hp, etc. Not the B.

ski

That conflicts with the current SAE standard, which mandates that all engine accessories and the stock exhaust system be installed and fully functional.

Bmr4life

I also saw the Hot Rod episode. Like its been said before. 450hp at the crank is probably standard with NO accessories or exhaust hooked up. Our stock 4.6's would probably make 330-335hp if tested that way.

This motor trend video is definitely referring to CRANK hp. They NEVER talk about RWHP because your average consumer has no idea what RWHP even means. Motortrend put that mustang on a dyno, got a RWHP number, then CALCULATED a crank HP of 436 based on an estimated drive train loss.

NaplesFL11GT

MM&FF did a test on a dyno with the 3V and with no accessories it hit close to 370 crank HP. Going to have to dig the issue out and see which month it was.

Bmr4life

Wow, our accessories suck.

JIM5.0

Actually, alot of Europeans use the PS instead of HP, and even the PS is not brake. PS is the German form of HP, which is the metric form of our SAE (British Imperial) horsepower. But alot of Euro people simple call their PS simply as horsepower also.

Note that HP or PS, is not always brake. you have calculated HP and you also have calculate PS, both of which are not brake.

When you factor in all the frictional forces (thus they have a "braking" effect on slowing down the engine internally), then you get either BHP or BPS.

The HP advertised at the crank is from experimentation and measurement of an actual engine on a dyno, thus you get the internal frictional forces (the "braking" forces). Additionally, I believe SAE standards requires that belts, the alt, starter, AC compressor, and all that other stuff be installed on the engine when it is mounted on the dyno to measure the crank HP.
In this case, the crank HP as advertised is BHP.
Or in Europe, if they have similar requirements, they would have BPS

In summary, RWHP is brake HP, and according to SAE standards, even the crank advertised HP is also brake HP.
It is not incorrect to call either RWHP or crank HP as brake HP.

Bmr4life

I suggest we don't use BHP then as it is to broad. We should stick to CRANK (HP) or RWHP in our discussions.

siggyfreud

I was using Crank horsepower as REAL power, as the OP seemed to be curious about what the engine really makes. Wheel horsepower isn't really a measurement of the engine's horse power, but just part of the formula. Which I know you know.

SXGT I am well aware they are not the same thing. If an engine, on an engine dyno makes 300hp, I would consider the engine's real power to be 300. Whatever it puts to the ground is the car's real power, as that is a combination of the engine and drive-train.

I think the OP was seeing the differences in crank/wheel HP numbers and wondering if there was some third number that was actually the correct power figures.