A six-stroke reciprocating engine that combines a four-stroke internal combustion cycle with a two-stroke Rankine cycle is presented. A heat regenerator extracts the residual energy of the combustion gases expelled during the exhaust stroke of the internal combustion cycle. The heat regenerator is located in an antechamber directly adjacent to the cylinder to minimize heat losses and maximize the temperature of the captured energy. During the Rankine cycle liquid is injected directly onto the heat regenerator where it vaporizes and superheats. A multi-link arrangement is incorporated into the engine's reciprocating mechanism to provide for dynamic clearance volume adjustment. This dynamic adjustment allows maximum expansion of the vapor during the Rankine cycle and provides the proper compression of the intake charge during the internal combustion cycle. Modeling of the engine performance predicts a thermal efficiency for the combined cycle of 56%.