In the present investigation, tests were carried out to determine engine performance of a naturally aspirated direct injection diesel engine fueled with diesel and jatropha methyl ester blend (JME20). Comparison of performance was done for different values of compression ratio, injection pressure and injection timing to find best possible combination for operating engine with JME20. It is found that the combined compression ratio of 19:1, injection pressure of 240bar and injection timing of 27$bTDC increases the brake thermal efficiency.From the investigation, it is concluded that the both performance was considerably improved for JME20 compared to diesel.

Keywords: diesel engine, injection timing, injection pressure, jatropha oil methyl esters, performance, emission, combustion characteristics