A computer - controlled valve actuation system for research engines is described. The system can be used for the complete real-time control of valve motion, including valve lift, dwell, valve event overlap and valve timing. The value actuator is a fast electro-hydraulic unit, incorporating a small hydraulic actuator and a high-performance servovalve. The actuator assembly mounts over the engine valve and replaces the existing camshaft and rocker arm. An analog position-feedback controller coupled to a laboratory minicomputer provides the system control. The closed-loop step response time is 3 milliseconds with a 0.5 millisecond initial delay. The system currently operates at engine speeds less than 1000 rpm and with appropriate control software is expected to operate at engine speeds approaching 3000 rpm. The actuation system is suitable for a research environment and has many potential applications in piston engine research and development.