Just a thought on the percentage loss. A trans and differential will take a certain hp to turn no matter what engine is in front of them. There are other inefficiencies through the drivetrain such as brake drags and bearing drags that you can not get exactly right. Force is a factor of mass times acceleration not including drag/heat efficiency losses so I agree that if you spin them up faster they will take more hp but it is not proportional. A 165hp 318 will still overcome the same losses as a 600hp one. Maybe I am wrong but I think any percentage loss is just a SWAG.