Speed control of kerosene engine by the combination of a manual throttle and centrifugal weight type governor is not adequate for evaluating energy requirements in laboratory and field performance tests. This paper describes an engine speed control system. This system consists of Apple-II microcomputer, step motor set to the throttle shaft directly, step motor driving and interfacing circuit, engine performance data acquisition system for measuring load, speed and time and potentiometer as speed adjustor. The performance of this system was successful in maintaining engine speed within ${pm}37$ rpm of reference speed indicated by computer and potentiometer.