Originally Posted by Chip

Im not trying to do any such thing, I dont beleive that there is an accurate way to measure the power of an engine once its installed in a car, other than to quote the amount of power that ends up at the wheels, I dont believe its possible to derive from that an accurate figure showing how much its actually making at the flywheel by any means I have available to me, or anyone else who uses a rolling road for that matter.

That is why DD rollers dont even attempt to measure the rundown losses or anything like that, as they know it isnt accurate, so they just allow you to add a % which vaguely represents loss, its NOT intended even by the makers to be accurate though as far as im aware so its pointless anyone else treating it like it is definitive.