How does elevation above sea level affect engine power?

As elevation above sea level increases, the density of air decreases. This reduction in air density means that there is less oxygen available for combustion in the engine. Since combustion requires a specific ratio of fuel to oxygen, less oxygen results in incomplete combustion, which ultimately leads to a decrease in the engine's power output.

Engines are typically designed to operate optimally at sea level, where the air is dense and provides enough oxygen for combustion to maximize power. As a result of elevated locations, you would find that engines lose power because they cannot draw in or utilize as much oxygen. This decrease in available oxygen leads to a reduction in the efficiency of fuel combustion, resulting in less horsepower being produced, which is why engine power decreases at higher elevations.