Abstract: A device for increasing fuel efficiency in an internal combustion engine and for reducing emissions, including a rotor assembly positioned entirely within the manifold of the engine and including a post secured to the bottom of the manifold below the carburetor and mounting a freely rotatable rotor on the top of the post adjacent the carburetor opening of the manifold. The rotor includes a plurality of angled slots therethrough whereby the flow of the combustible mixture impels the rotor to spin. The spinning rotor causes the droplets of gasoline to further vaporize, thus boosting the fuel efficiency of the engine and reducing emissions.