FAA Powerplant Written Practice Test

How does thermal efficiency affect an engine?

1. Affects the fuel consumption of an engine

2. Increases engine weight

3. Reduces horsepower

4. Improves exhaust emissions

The correct answer is: Affects the fuel consumption of an engine

Thermal efficiency is a measure of how well an engine converts the heat from fuel into useful work. When thermal efficiency improves, the engine is better at converting energy from fuel into mechanical energy, which directly affects fuel consumption. Higher thermal efficiency means the engine can achieve more power output from the same amount of fuel, leading to lower fuel consumption for a given power requirement. Hence, if an engine has high thermal efficiency, it will use less fuel to produce the same amount of power compared to an engine with lower thermal efficiency. This is particularly important in aviation and automotive applications, where fuel costs can be significant and efficiency is crucial for performance and range.