As mentioned there are a lot of variables to consider. Even so, when I'm looking for a ballpark estimate I use 15% loss for manual transmissions and 20% for automatics.

If a car makes 400rwhp for example, I do the math like this:

manual....400/.85 = 470 engine hp

auto........400/.8 = 500 engine hp


again just an estimate smile

Last edited by BigDaddy440; 05/12/21 01:03 AM.
1969 A12 Roadrunner
1970 Plymouth Cuda
1968 Dodge Dart