I had a quick question on the loss of power of a vehicle through the drivetrain and figured someone here could better explain it.

Suppose you have a vehicle whos engine dyno's 200hp, and the vehicle dyno's 160whp... there is a drivetrain loss of 20%.

If you take this same vehicle, with the same motor and same drivetrain assembly... and now its producing 200whp, is it safe to assume the drivetrain loss will remain at the same percentage and its power at the crank is now 250hp?

I was curious to know as you increase the power on a vehicle is the percentage loss through the drivetain constant or not?

TIA
-hS

 

It depends, but in most cases, if you are dealing with horsepower under 400, then it should be pretty linear.

As power increases, little things such as gear meshing, and the fluids used, all the way to the amount of tread on the tires can have greater and greater effect.

 

I was thinking along the line power is lost in the drive train because power is used to turn those parts, and hence the amount of power you have at the end (the wheels) is what is remaining.

As you increase power in the engine, how much of an increase is needed to turn the drivetrain?

Interesting you mention 400hp because i've seen on some higher horsepower cars where the engine power and the wheel power is much more similar than a lower hp car.

carry on
*grabs popcorn*

 

all interial losses are proportions to the square of the change of rotational speed... the more power, the faster you spin things up, the more losses you will get (squared)

most frictional losses will be proportional to the power... so those will go up linearly with power