Abstract
A new gasoline combustion engine system with high compression ratio was studied and proposed in order to achieve higher thermal efficiency than that of a conventional SI engine. A special cranking mechanism was adopted which allowed the piston to move rapidly near TDC. Some mechanisms were proposed and two of them were designed and built for the testing. The experimental results showed that knocking was avoided and better indicated thermal efficiency was obtained. An inconstant speed gear mechanism with compression ratio of 14 could be operated up to 2500 r/min and thermal efficiency was improved by 18% compared to a conventional engine with compression ration of 10. Also, a cam mechanism driven by a planetary gear was tested to achieve higher engine speed up to 4000 r/min, but the improvement of thermal efficiency was not so large as much as of the inconstant speed gear mechanism.
