May 13, 2005 1:03:15 PM
- 69bossnine
- Rennteam Pro
-
- Loc: FL, USA , United States
- Posts: 2028, Gallery
- Registered on: Jan 27, 2005
- Reply to: Dilinger
Re: My 997c2 dyno
Quote:
Dilinger said:
What size are the wheels of your car?
This is important when measuring HP on the wheel
Dilinger, the wheel size only changes the effective gear ratio, not the HP measurement. A larger wheel has less leverage in the same gear, but will generate more drum speed. The horsepower measurement is taken across a range of drum speed, point "a" to point "b", also taking into account engine rpm at point "a", and engine rpm at point "b". It's not a static-speed measurement. Therefore, wheel size is irrelevant. Parasitic drag between the flywheel and the wheels will affect rear-wheel horsepower, but leverage does not, as drum speed increases congruently with leverage loss.
