PERFORMANCE TUNING OF AN IC ENGINE BASED ON PRESSURE WAVE PROPAGATION WITH A CONTINUOUSLY VARIABLE EXHAUST RUNNER LENGTH AND EXHAUST VALVE TIMING SYSTEM

The momentum of exhaust gas flowing out of the valve creates a pressure wave which can have a positive effect on the evacuation of gases. This concept is known as wave tuning, utilizes the sub-atmospheric pressure waves in the runner to evacuate more exhaust gases. When tuned precisely by varying length and/or exhaust valve timing in such a way that the wave returns in accordance to the exhaust valve opening, it creates a scavenging effect and this improves the engine performance. In this research both exhaust runner length and valve duration have been changed to arrive the sub-atmospheric wave at exhaust valve to improve the performance of the engine using Ricardo WAVE software. It was found that varying the exhaust valve timing managed to improve the torque by 1-3% at different rpm. However, varying both length and timing improved the toque 7-10% at lower speed and 3-6% at higher rpm.