The Sowda^® Engine mechanism provides the most fuel efficient engine in the world. The high efficiency is accomplished by providing an infinitely variable compression ratio applicable to both 2-cycle and 4-cycle engines. With the infinitely variable compression ratio, the engine can automatically adjust the top dead center height of the piston so as to maintain a constant pressure ignition (CPI). Emission are dramatically reduced. Additionally, the 4-cycle engines have two distinct stroke lengths: short intake/compression strokes and longer power/exhaust strokes so as to extract maximum power. Typically, the power/exhaust strokes are 40% longer than the intake/compression strokes. Exhaust temperatures are dramatically reduced as more power is extracted.