A new and improved combustion-powered linear air motor/compressor wherein the new and improved combustion-powered linear air motor/compressor comprises new and improved structure for achieving the scavenging of residual combustion products or exhaust gases from the combustion chamber during the return stroke of the power piston assembly. More particularly, the speed and efficiency of the scavenging of the residual combustion products or exhaust gases is able to be achieved as a result of the power piston assembly causing fresh or ambient air to be rammed or forced into, through, and out of the combustion chamber during its return stroke.