Do manufacturers quote flywheel or wheel horsepower?

[Whatnotacos]

Something i have just thought about

When car manufacturers release the power output of the cars, is in flywheel horsepower or wheel horsepower?

For example my Saab 9-3
175hp factory, Does this mean I make around 150hp to the wheels with 15% drive train loss? Or is it 175 + the 15%?

or lets say...202 crank horse power, so 175Hp at the wheels?

If anyone has any input it would be helpful.

[Whatnotacos]

SnailTrail said:

I'm fairly sure they normally quote the power the engine makes.

OT but don't they dyno the engine minus a lot of auxiliary stuff as well to increase the figure?

It would not surprise me, could even be making much less.

[Whatnotacos]

Scuffers said:

Err...

Wheel horsepower as a empirical measure, does not exist.

You know perfectly well what I'm getting at.

[Whatnotacos]

Scuffers said:

Then why ask?

You do realise that are standards for this stuff?

You think they would just use some random rolling road to get their published speces?

I asked because I do not know which power they publish, the power at the crank or the power which would drive the wheels (with drive train loss). I think they would have to be accurate but I'm not sure which they are supposed to publish: Crank or minus drive train loss.

Do you know?

[Whatnotacos]

Scuffers said:

So, just how do you propose they get 'accurate' figures from something that's totally uncalibrated, has no standards, etc etc?

What do you think?

I don't expect the figures to be accurate,the engine would have variations in power with different atmospheric conditions
as well as of course loss of efficiency of the years.

Let me phrase it this way, Do they quote the crank/flywheel horsepower in the specs? however accurate they may be.

(Never did I mention accuracy, power output changes with many different factors)

[Whatnotacos]

RobDickinson said:

They quote engine power withotu drivetrain.

Dyno's often measure the energy taken by the powertrain in a run down and use that to back calculate the engine power.

Thank you very much, that's a straight answer!

[Whatnotacos]

ging84 said:

it's at the fly wheel

of course it is, manufactures are always going to go towards quoting the bigger numbers

I suppose that makes sense, why would they say it would make 150bhp when they can say it makes 175.

Thanks very much