I'm not too critical of the Magnum response. A statement that an engine makes 1.7 BHP tells you very little. Horsepower is RPM times Torque times some constant. Even as statement that an engine makes 1.7 BHP at 22,000 RPM isn't too useful if you want to run the engine at 10,000 RPM. The most useful kind of test is where they tell you the fuel, glow plug and atmospheric conditions and show a torque and horsepower curve on a graph versus RPM. This is done with calibrated test props. Then they tell you what RPM they got with various props, including the ones you want to use. Peter Chinn used to publish this sort of test in Aeromodeller and Model Airplane News. I run some older engines, and I have found his tests to be very informative.

Jim