Parasitic losses due to the drivetrain are a percentage of total transmitted power. Most loss factors (gear tooth friction, bearing friction, shaft friction) increase linearly with load. This is why towing packages on trucks often include a transmission cooler, to dissipate the extra friction that is produced under higher load. In a similar way, adding HP increases the tranny load (friction losses) and therefore robs more power.
Here at work we design transmissions for Aerospace applications and we typically use
1% loss per gear mesh. HTH
flyer
