The present work describes a theoretical investigation concerning the performance of a four strokes compression ignition engine, which is powered by alternative fuels in the form of diesel and biodiesel blends. The developed simulation model used to estimate the cylinder pressure, heat release rate, brake thermal efficiency, brake specific fuel consumption and engine out emissions. The simulation model includes Honerberg’s equation heat transfer model, Zero dimensional combustion model for the prediction of combustion parameters and NO formation during combustion process using Zeldovich mechanism.Experiments were performed in a single cylinder DI diesel engine fuelled with a blend of pungam methyl ester for the proportion of 10%, 20% and 30% by volume with diesel fuel for validation of simulated results. It was observed that there is a good agreement between simulated and experimental results which reveals the fact that the simulation model developed predicts the performance and emission characteristics of any biodiesel and diesel fuel and engine specifications given as input.