An engine with a brake horsepower of 20bhp would have rated of?

To calculate the rated power of an engine with a brake horsepower of 20bhp, we need to know the mechanical efficiency of the engine. Mechanical efficiency is the ratio of the power output of an engine to the power input. It takes into account the losses due to friction, heat transfer, and other factors.

The formula for mechanical efficiency is:

Mechanical efficiency = (Brake horsepower / Indicated horsepower) * 100

Where:

Brake horsepower (bhp) is the power output of the engine measured at the crankshaft.

Indicated horsepower (ihp) is the theoretical power output of the engine without considering any losses.

For most gasoline engines, the mechanical efficiency is typically around 75%. This means that for a 20bhp engine, the indicated horsepower would be:

Indicated horsepower = (Brake horsepower / Mechanical efficiency) * 100

Indicated horsepower = (20 bhp / 0.75) * 100

Indicated horsepower = 26.67 ihp

Therefore, the rated power of an engine with a brake horsepower of 20bhp and a mechanical efficiency of 75% would be 26.67 ihp.