question on HP and how its measured (LAC)

[Dupree, Jim]

Normally the published ratings are crankshaft HP & torque. Most are probably
calculated and not test stand numbers.

I have been told different thing with regards to hp measured at the wheel. I
have heard of 15% loss, 25% loss and several different set HP 's loss
measuring this way. We were told when we dyno'd a 914 track car that there
was probably about 70hp loss. This is a 3.2L 911 6cyl engine with twin plug
ignition, carbs and headers. It measures 227HP at the wheels and we were
told it should be making close to 300 HP at the crank. Is there any standard
or method for figuring the loss?

Thanks
Jim

 -----Original Message-----
From: 	Tony Lum [mailto:tlum at flash.net]
Sent:	Tuesday, July 23, 2002 11:52 AM
To:	quattro at audifans.com
Subject:	question on HP and how its measured (LAC)

Hi gang,

Since we have a discussion on horsepower today, I was wondering where
manufacturers are specifying the rating.  Is it at the crankshaft or at the
wheel?  If its at the crankshaft are the manufacturers measuring the output
on a test stand?

For reference, some of you may recall that I ran my urq on the 4 wheel dyno
at ATP a while ago and recorded a max of 152.2 HP at the wheel.  In
contrast, a stock A4 1.8T rated 150HP, measures only 99 at the wheel.  On
the other hand a modified S4 (2.7 V6 bi-turbo) measured 295 HP at the
wheels.

Regards,

-Tony
urq #900302