What is lean combustion?

Lean combustion refers to a condition in which there is more air relative to fuel in the combustion mixture than what is required for complete combustion. When this occurs, the air-fuel mixture is said to be "lean." This leads to more air than the optimal stoichiometric ratio, which is the ideal balance of air and fuel that achieves complete combustion.

In lean combustion, the excess air helps improve fuel efficiency and can reduce emissions of certain pollutants, as the combustion process is more complete. However, it can also lead to issues like higher combustion temperatures which might cause engine knocking or pre-ignition if leaned out too much.

Understanding lean combustion is essential for optimizing engine performance, fuel efficiency, and emission control in modern engines.