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 other piece of the puzzle not mentioned is
power is work performed/time, so yes, 200 hp at 50 mph shouldn't have any more frictional losses than 300 hp at 50mph, everything *should* be moving at the same speed in that instant, but power is not an instantaneous measurement, but rather a time averaged measurement, and so that 300hp is revving up the system at a quicker rate resulting in a higher absolute power loss.