Optimized valve timing, according to engine load, may lead to significant improvements in pumping losses and internal EGR generation. Thus, VVT technology constitutes an effective way to reduce both fuel consumption and pollutant emissions.
In this paper, the behavior of a small displacement, 2 valve, Spark-ignition engine, with variable valve timing, has been numerically and experimentally analyzed.
The use of VVT allows obtaining combined internal EGR and Reverse Miller Cycle effects so to achieve a significant dethrottling at part load operation.
High EGR rates require high turbulence intensity in order to accelerate the combustion rate. The engine performs an accurate combustion chamber design and a tangential intake port able to generate optimized swirl motion, according to the engine speed and load, during both the exhaust gas re-aspiration and the intake stroke. Engine performances at different cam phaser positions have been calculated by means of a 3-D computer code. Many of the obtained results have been compared to the measured data provided by ELASIS research center.