Which mixture type is less likely to cause detonation in the engine?

A rich mixture is less likely to cause detonation in an engine due to its higher fuel-to-air ratio, which helps in cooling the combustion process. In a rich mixture, there is more fuel present than needed for complete combustion. This excess fuel absorbs some of the heat generated during combustion, which can help prevent the peak temperatures that lead to detonation or knocking. Additionally, since there is not enough air for all the fuel to burn efficiently, the combustion happens in a more controlled manner, reducing the chances of unwanted auto-ignition of the fuel-air mixture. This makes rich mixtures safer in terms of detonation, especially under high-load conditions.

In contrast, lean mixtures (which have less fuel relative to air) can lead to higher combustion temperatures and greater susceptibility to detonation. Balanced mixtures may provide optimal combustion but are not specifically designed to prevent detonation as effectively as rich mixtures. Weak mixtures generally have too much air compared to fuel, leading to inefficiencies and potential misfire rather than a detonation-triggering situation.