The Effects of Valve Timing on Performance Characteristics of Converted CNG Engine

Converting diesel engines to ones using compressed natural gas (CNG) is an efficient and suitable solution for addressing environmental pollution and depleting fossil fuels. In this paper, a study on the effect of open valve timing on brake torque of a converted CNG engine with port injection type fuel system was studied. The result of the simulational method using AVL Boost software has indicated that the open valve timing needs to be corrected earlier than that in the diesel engine to reduce the pumping losses of the intake and exhaust process. One of the critical factors required to increase brake torque is to reduce the amount of pumping losses in the exhaust process.