Tubby Vs New Audi RS4 (420bhp)

[Andy Champ]

surely the only thing a rolling road can measure is the force from the contact patch spinning the rollers, that force is the tractive effort from the car. The computer in the dyno knows how big the rollers are, so converts this force into a torque, which it can then convert into power, no?

Given known moment of inertia and known acceleration, you can calculate the rate of change of kinetic energy. That's power.

Given known engine revs, you can get the torque for the engine. Without the engine revs, you can get tractive effort.

[Andy Champ]

Can't say what gear/revs any of us were at but i would say between 4000 and 5000 for me and between 5500 and 6500 for him. We were both absolutely gunning it.

I admit I'm surprised. I can't see how the 130 would beat the 150, if both were being driven at max power.

Your never going to give in and i'm getting fed up saying the same things over and over. This thread has went from off topic to way off topic to off the scale off topic. It was very interesting for a while reading all the different views and digesting all the relevant information but even the information you provided backed up my views.

Just one last thought then. When you're doing a quarter, or a 0-60, or whatever, do you run at peak torque or peak power? Remember there is a special case, at the beginning where traction is the limiting factor and not the engine.

Now lets go driving instead!

Andy