Abstract: In a closed Stirling Cycle system gas, such as dried air, is heated and expanded within a power piston chamber, driving the power piston outwardly of the chamber into contact with a cam groove of a flywheel, rotating the flywheel. When the power piston reaches the top of its stroke, the cam slope reverses, and drives the power piston back into its chamber expelling the heated gas therefrom into one or more cooling chambers, cooling and contracting the gas which is then charged into a recovery piston chamber, driving the recovery piston outwardly of its chamber into contact with another cam groove of the flywheel. When the recovery piston reaches the top of its stroke, its cam groove reverses and drives the recovery piston back into its chamber, expelling the cooled gas therefrom back to the power piston chamber recommencing the power cycle to drive the flywheel. Preferably, several pair of power-recovery pistons operate out of phase to drive the flywheel.