Quote:
Originally Posted by gramicci101
Ok, you're an engineer, so hopefully you can explain this to me. Why is drivetrain loss expressed as a percentage instead of a static number?
Say your car makes 200 bhp, and for ease of math it loses 20 hp (10%) through drivetrain loss. You do some mods to it and now it's making 300 bhp. You're still spinning the same gears at the same speed in the same fluid, so it should still only lose 20 hp, not 30 hp (10%), right? If expressing it as a percentage is correct, why would drivetrain loss go up just because power went up, when the workload to spin all the gears and whatnot hasn't changed?
|
The simplest explanation is more torque = more friction = more heat = more loss. The percentage comes from the individual friction sources which is a dynamic loss combined with the loss of the energy from all mass of the moving components. Accelerating a mass takes energy, accelerating it faster takes more energy, While the percentage expressed as drivetrain loss is not always 100% accurate it's a good way to oberserve its effects.
I hope that helps, I'm sure more knowledgeable people then me will chime in.