What is the optimal fuel-to-air ratio for best power?

The optimal fuel-to-air ratio for best power in a typical internal combustion engine, especially in aviation applications, is approximately one part fuel to 14 parts air, known as the stoichiometric ratio. This ratio allows for complete combustion of the fuel and maximizes the engine's efficiency and power output. At this balance, there is enough oxygen from the air to ensure that all the fuel can be utilized, leading to maximum performance.

In contrast, a leaner mixture (such as one part fuel to 16 parts air) can lead to incomplete combustion, reducing power. Conversely, a richer mixture (like one part fuel to 10 or 12 parts air) can provide more fuel than the air can combust, resulting in wasted fuel and excessive hydrocarbon emissions, potentially leading to fouled spark plugs and decreased overall efficiency.

Understanding this optimal ratio is critical for pilots and engineers in managing engine performance, especially when adjusting mixtures for various phases of flight, such as takeoff and climbing, where maximum power is typically desired. Thus, the choice of one part fuel to 14 parts air stands as the benchmark for optimal power output.