An Experimental Study on Fuel Injection System and Emission of a Small GDI Engine

A newly developed " common-rail-valve-nozzle" hole type injector for a small direct injection spark ignition engine (125ml) is introduced in this paper. The injection parameters were adjusted by a high speed solenoid valve (HSV) numerically controlled. Based on testing results, the influences of air-fuel ratio and injection timing on performance of GDI engine are analyzed. Results show that the lean-burn limit can be extended and the fuel economy and emissions can be improved by using the combination of injection quantity with injection timing adjustment.