An experiment... 5 Horsepower engine connected to a dynamo meter with a fuel supply and all the whistles and bells. The engine was throttled at differing rpm and readings of Torque, Exhaust temperature, Air Flow, and Fuel Consumption were taken. Its amazing how interesting this experiment actually is, if you haven't done it, I'd strongly recommend you find the means to do it.
Many things can be found out from engines, espically if you do not normally work with engines.
Anyway, back to work