How does humidity affect engine performance?

The impact of humidity on engine performance primarily relates to the changes in air density and the combustion process. When humidity levels are high, the air contains more water vapor, which is less dense than the oxygen it replaces. This reduction in air density can lead to less oxygen being available for combustion in the engine, thereby decreasing the overall efficiency of the engine.

As a result of the decreased efficiency, the engine may produce less power or thrust because it is not able to burn fuel as effectively as it could in drier conditions with denser air. This is particularly evident in piston engines and turbocharged engines, where air density plays a crucial role in performance. Consequently, high humidity levels ultimately contribute to decreased performance rather than enhancing it or having no effect at all.