A mechanism for Internal Combustion (IC) engines, wherein such mechanism improves the efficiency and power output of IC engines through dividing the conventional connecting rod between the crank shaft and the piston into two parts; a first part and a second part, and connecting these parts together by a pin joint, wherein the second part slides through an oscillating rocker that is connected to an engine block by another pin joint, thus adding a degree of freedom to the conventional connecting rod. The mechanism may be retrofitted in an existing combustion engine without the need for any significant change in the design of the engine. The mechanism may replace the traditional connecting rod that connects the piston with the crank shaft of the engine and comprises essentially a primary connecting rod, a secondary connecting rod, and an oscillating rocker.