Originally Posted by
Sport_Pilot
200 RPM is much more than 2%. Take a look at the formula for propeller torque and speed. To raise the RPM by 200 RPM the torque must increase exponentially so a 2% increase in speed is more like an 8% increase in torque, and HP may be more like 10%.
The only real method I have at my disposal to determine power production of an engine is how fast it will turn the propeller. I have no way of measuring the HP or torque of the engine except through how the engine turns the prop. If an engine turns 200rpm faster and burns 10% more fuel, it wouldn't be worth it to me. 400-500rpm would be more "worth it" in my eyes.
I do not doubt what you're saying though.