A dyno doesn't measure hp. It measures torque. HP are calculated from torque and rpm.
There are different parameters that can affect a measurement:
- Temperature
- Humidity
- Grip
- Fuel quality
- Air filter, sparks…
If you don't use a calibrated and certified dyno, measurements are just written lines on a piece of paper.
Funny how people are hunting for 5 hp at the top end. Useless to say that this doesn't affect the driveability of the approx. 250 hp car in any way.
But keep on searching. Always funny to me.
Just my 2 cents.
Markus