M.R Zangooee Motlagh - Department of Engineering mechanics, Ferdowsi University of Iran, Mashhad, Iran
M.R Modarres Ravavi - Department of Engineering mechanics, Ferdowsi University of Iran, Mashhad, Iran

This paper presents the effect of injection timing on performance and emission of a new GDI engine that has been developed from modification of a multi point fuel injection (MPFI) engine. In this study the new engine at the speed of 2500 rpm with different injection timing was simulated with KIVA-4 code. The Results are compared with those were obtained from the MPFI engine experimentally. The objective of this investigation is to find the optimum injection timing for new engine. This paper has shown that there is an optimum interval for injection timing in which the engine performance is the highest. The results show that this optimum injection timing is 142 BTDC. Generally, the output power of the GDI engine is more than the MPFI engine at the same operating condition. It is worth nothing that for the mentioned interval, the CO is higher and the NOx emission is lower than the MPFI engine.

GDI engine, MPFI engine, XU7, injection timing, KIVA-4