A carburetor for a 1968 six-cylinder Ford engine was modified to meter gasoline into the engine through an ultrasonic horn. The engine, mounted on a test stand, was loaded by a water dynamometer. The tests were performed with the horn alternately activated and deactivated for two different tip configurations. Engine operating data were taken at five throttle positions and thermal efficiency and specific fuel consumption were determined for each of these positions. Marked improvement (5-10%) in these parameters was obtained at an ultrasonic power input of 20 watts.