HP numbers are very deceptive.

HP is calculated by multiplying torque * RPM. So you can have an engine that puts out a lot of HP at a high RPM but very little at lower RPMs. If the peak HP is at an RPM that you cannot use then the number has no meaning. For example if the HP peak is at 10,000 RPM on a 58 cc engine that HP number would be useless in an aerobatic plane since the props you need to use would be very inefficient at that speed. It would be nice in a racer though.

So what we want to know is what is the HP figure at the engine's torque peak, this is the real sweet spot for power production.

Until such time as manufacturers put HP and torque graphs in their literature HP figures will continue to be useless, we will need to go by what works and what doesn't.

TF