Lean Combustion in a High Compression Four Stroke Gasoline Engine

To achieve lean combustion in a gasoline engine, a swirl type combustion chamber is placed in the piston top. The compression swirl thereby created makes a rapid combustion possible, which is essential to a lean burn engine.

The experiments are carried out with a single cylinder four stroke engine, mainly at a compression ratio of 13.8:1, and are compared to a Heron-type combustion chamber.

Minimum fuel consumption is obtained at an air-fuel ratio of 19, and as an average, an improvement of approximately 5 per cent is found.

The peak cylinder pressure is reduced in comparison to the Heron chamber at the same compression ratio.