Lower Specific Fuel Consumption with High Compression Lean Burn Spark Ignited 4 Stroke Engines

General aspects to improve the thermal efficiency of four stroke spark ignited internal combustion engines. Lean air-to-fuel ratios and high compression ratios call for a revised combustion chamber shape. One practical simple and cheap concept has been realized and tested on a large variety of engine sizes and types. Some test results are shown to evaluate the potential of lean burn high compression engines.