Originally Posted by
oldford
I once measured the same car on the road in both cold (-10 degrees Celsius) and warm (32 degrees Celsius) weather.
In cold weather i measured 325 bhp and in warm weather 295 bhp. That's about 10% difference in total.
Nominal the engine had 305 bhp. (At 21 degrees Celsius. the car was a Sierra Cosworth 4x4.)
I have not done a comparison with any measuring data but it would not suprise me what you have said as the difference I can feel is real! Likewise on a very hot Summers day performance is less.