Originally Posted by afm

This is the explanation given by the Dyno Manufacturer

X-Dyno Horsepower vs. Claimed Horsepower

You may have noticed that X-Dyno power data doesn’t always match up with manufacturers’ claimed horsepower and torque figures. We attribute this discrepancy to the fact that many manufacturers publish theoretical horsepower and torque figures based on rough estimates rather than actual dyno data, or that a manufacturer’s data collection protocol doesn’t match our own. The X-Dyno calculates horsepower using known mathematical formulas and precise physical data measurement.

This means that since there is no RC Industry Standards for measuring Hp and torque figures, which are affected by ambient conditions (temp, humidity, air density, altitude, air vapor etc. etc.), you have to use a correction factor like for example SAE JI349 relative Hp factor.

Although the X-Dyno’s power numbers may not equal the numbers you’re accustomed to seeing, the figures they provide are accurate from engine to engine, and are directly comparable with power data from test to test. All engines are tested equal using correction factors, so it is a reliable source for comparing engines.

AFM