A High Efficiency SI Engine Concept

A single cylinder test prototype developed from a production engine required only a modified camshaft, piston, and intake manifold to achieve a continuously variable compression ratio, an extended expansion ratio, and a wide range of operation at WOT. This prototype has demonstrated substantially reduced BSFC, reduced ECT, and reduced CO, CO₂ and NO_X exhaust emissions when compared to an unmodified identical production engine at equal rpm and torque. This mechanically conventional concept retained fixed valve timing, carburetion, and mechanical torque and speed control, and offers a means of achieving high fuel efficiency in a simple, relatively low cost design.