The ideal air-to-fuel ratio in a typical engine is approximately 14.7:1. This means that for every 14.7 parts of air, 1 part of fuel is required for optimal combustion. This ratio is known as the stoichiometric ratio, where the air-fuel mixture is chemically balanced to achieve complete combustion. It provides the most efficient and cleanest combustion process, leading to optimal performance and minimal emissions in gasoline engines.