JimGreek wrote:Since I must make a decision about what you guys will read in the V6 book, I will ask for a general opinion on it. Do you want the book plots to only show wheelpower? If you want engine power, what do you think is a reasonable loss for transaxles?
Good question about losses, but unfortunately there's no universal answer on it.
Real losses aren't only prosentage part of the engine power. There are also some losses which are dependent on driving speed, tyre type/size and axle weight, but not much to do with the amount of power transferred via driveline. That means the total loss prosentage value may vary a lot and the number is typically lower with high power engines.
The prosentage loss of engine power is also there and it can also vary depending what kind of tyres and dyno is used. The transmission teeth contact loss is easiest and least changing part, but the tyre-roller contact does a big differences. In worst cases there may be even 10% slipping on the contact and it still feels like tyre does well.. 10% slip means also 10% power loss in only this part of the whole loss chain..
Those wheelpower values you got are really very near to each other, but there's also some luck on the game. Anyway, the wheel power is still the best number to compare.
If having access to engine dyno, it would be good idea to do a comparison between it and the chassis dyno you are using. Later using same tyres and similar mounting of the car on the same bench will quarantee reasonable accuracy for absolute power values. Relative values will usually work, if nothing else changes..
As people use to want to hear about engine powers, if claiming something there should be heavy note that the values are based on certain approximations. After all, maybe you should give some values to satisfy the readers.
assumed 
total losses. This has always seemed high to me and I tend to go looking for the 50kW heat exchanger it is being lost through 
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