Reciprocating engines are nothing more than energy conversion devices.
What's really interesting is how well, that is how efficiently, a given reciprocating engine converts its fuel to useful work - horsepower. The relative energy conversion efficiency of any two engines can be determined by looking at their BSFC numbers. BSFC stands for Brake Specific Fuel Consumption. It's a measure of how many pounds of fuel an engine consumes per hour per useful horsepower that the engine produces. Dynamometer tests of the Travis-100 disclose that it is capable of a maximum of 300 horsepower.