ABSTRACT:In this study, a prototype four-stroke spark ignition engine with four-cylinder (that each cylinder has two valves), with and without turbocharger which equipped with a system to adjustment of variable valve duration has been investigated. This study covers the effects of intake valve opening (IVO), Intake valve closing (IVC), exhaust valve opening (EVO) and exhaust valve closing (EVC) angles on engine performances and fuel economy. The calculations of engine performance were carried out using the1-Dimensional simulation with AVL BOOST software. The effects of different valve timing strategies and a combination of them from simulations were analyzed and compared with the reference fixed valve timing cases. It has been shown that substantial improvements in fuel consumption and performance can be achieved. The improvements of Indicate Specific Fuel Consumption (ISFC) are remarkable in turbocharged models. Furthermore, we can see the noticeable improvements in torque and power in the naturally aspirated engine.
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