The investigation of the effects of valve timing variation on engine performance and exhaust emissions in spark ignition engines

viTHE INVESTIGATION OF THE EFFECTS OF VALVE TIMINGVARIATION ON ENGINE PERFORMANCE AND EXHAUST EMISSIONSIN SPARK IGNITION ENGINES(M.Sc. Thesis)Fazıl AKGÜNGAZI UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYSeptember 2006ABSTRACTValve timing is one of the most important operating and design parametersaffecting the performance and exhaust emissions in spark ignition engines.Investigations on valve control systems proved that, especially by controlling theintake valve, decrease in fuel consumption and increase in engine performancewere obtained.In this study, a variable valve timing mechanism was designed andmanufactured. Intake valve closing timing was changed from 10º crankshaftangle (CA) advance to 10º, 20º, 30º CA retard according to the standart timing.Exhaust valve opening and closing timing, intake valve opening timing and liftwere not changed. A single cylinder, four stroke, spark ignition engine was usedfor the experiments.Depending on the engine speed, torque, volumetric efficiency, output power,specific fuel consumption and exhaust emission variations were investigated forfive intake valve closing timing values. The engine torque was increased by 10%viiat low speeds and it was increased by 4.6% at high speeds with variable intakevalve timing. Specific fuel consumption was increased by 6% at low and highengine speeds. Also, HC emissions was decreased.Science Code : 708.3.026Key Words : Spark ignition engine, intake valve timing,engine performance, exhaust emissionsPage Number : 81Adviser : Assist. Prof. Dr. Can ÇINAR