Real HP loss numbers

[Roger Heflin]

On Fri, 12 Mar 1999 goflo at pacbell.net wrote:

> Drive train losses are dissipated as heat, which is'nt impossible
> to keep track of on a chassis dyno - A drive train dissipating 
> 20-30% of big HP oughta be glowing in the dark... 
> 
> Jack
> 
> Bruce Plecan wrote:
> > BINGO,
> > So are many of these chassis dyno HP numbers being claimed, IMHO.
> 
> > >I wonder sometimes if people don't estimate drivetrain losses on the
> > >high side because they don't want to admit that their engines aren't
> > >as powerful as they want them to be.
> > >Dan L
> 
> 
There is also the question of how much of the hp lost is a percent of
the total hp going through the system, and how much is fixed, ie
double the hp of the engine, but still the same hp is lost in a
certain component.   I suspect things like brake rotors lose the same
hp, since hp would not seem to affect that friction.  So if a certain
car with a 300 hp engine loses 12% (36hp), you do not necessarly know
that the same car with a 400 hp engine will still loose 12% (48hp).
You can probably be fairly sure that the loss is between 36hp and 48hp
unless there is some part that loses hp in a nonlinear manner.   From
what few numbers I have see the more reasonably numbers are more like
12% for a manual and 17% for an auto, but as I mentioned above these
are at a given hp level, and the actual numbers could differ by a
number of hp.

				Roger