Abstract
The paper presents an experimental research work developed on a SI monocylinder engine equipped with a variable valve timing system designed by the authors, which uses a hydraulic action. This system equally allows the valves timing and the valves lift variations, fact which allows it self the engine load variation without acting the throttles obturator. There are compared the results obtained by using the inlet valve as load controller to those obtained by using the classic system load controller with the obturator. There are also presented the different influences of the improved system on the engine running.