Quote:
Originally Posted by eXo5
Wheel horse power
from what I understand vehicles are usually rated from the crank. 332 is rated at the crank the amount of HP you would get from a dyno is probably going to be around 280. HP is lost from a number of things. WHP is the HP being put down at the wheels. I am sure someone cant explain it better than I.
|
Correct - wheel horsepower is the power that actually makes it to the wheels.
Power can be lost in many things, because power is really just another form of energy. Its all lost in the drive train in one way, shape or form. The transmission is the first place its going to lose it, particularly in the clutch and gears. In an automatic, a stall converter will make your power at the wheels look HORRIBLE, but yet you will run amazing times at the track. Then it has to make it to the rear end, and even things such as the weight of the drive shaft will cause lost power. The rear end will be even more power lost, converting the power sent through the drive shaft and sending it to the wheels. Even the weight of the wheels alone will be lost power, due to unsprung weight needing to be spun.
Its not fair to simply say, "Well, the average power loss from crank to wheels is XX%". Look at RCZ - he "only" put down mid 250's in stock form at the wheels, but that is because the dyno he chose puts a load on the wheels, versus the OTHER dynos that say we're putting down 280's to the wheels. Those are simply drums that you spin up, that don't put a load on the wheels, and are considered to be less accurate.
There is a lot more science to this than a lot of people on here understand. You need to understand that wheel horsepower ratings can fluctuate on 2 of the exact same type of dyno's side by side - each one is different. Never mind even factoring in varying weather and altitudes...