IMPACT OF CAM SPLAY ANGLE IN A SPARK IGNITED ENGINE WITH VARIABLE VALVE TIMING

Variable valve timing (VVT) is a widely applied technology in internal combustion engine valve train systems. Dual independent camshaft phasing (DICP) is one VVT configuration. In this report, performance of a 4 cylinder, 16 valve spark ignited (SI) engine, with DICP, turbocharger, and direct injection technology is investigated with several sets of splayed camshaft applied on the valve train system. In VVT system, the phasing change of valve opening/closing operates within the phaser shift limits. Normally, in a four valve per cylinder engine, the valve timings and lift for the two valves of the intake are the same. However, by phasing one intake valve with respect to the baseline, difference in in-cylinder charge mass is observed. In this report, engine performance with splay camshafts under late intake valve closure (LIVC), and high overlap condition are tested. Specific fuel consumption, and engine combustion stability are two main quantity parameters analyzed and evaluated engine performance.