Abstract: A split piston in an internal combustion engine, having a base rockably secured to the connecting rod, and a detachable ring head which interfaces with the cylinder wall. The detachable ring head is snugly fitted onto a cylindrical extension of the base having an axis parallel to the cylinder walls, to allow removal on the head without removal of the engine crankshaft or connecting rod. The snug fit minimizes combustion gas losses and eliminates to need for gas tight seals, while allowing removal of the head. Threaded fasteners are used to secure the head to the base.