Effect of Injection Pressure and Injection Timing on Combustion Characteristics of Spray-Guided Direct-Injection Spark-Ignition Engine under Lean Stratified Combustion Operation

In this study, single cylinder engine experiment was carried out to investigate combustion characteristics spray guided direct injection spark ignition engine. In the result of engine experiment, it was shown that flammable window of injection timing was existed. The combustion efficiency increased with retarding injection timing, reaching a peak value, subsequent to decrease again. These results were likely due to the effect of ambient pressure on stratified-premixed mixture preparation 150 bar injection pressure condition and retarded injection timing from the best combustion efficiency injection timing showed the highest IMEP value due to the advanced combustion phase of the maximum combustion efficiency condition HC emission showed sane trend of combustion efficiency, and smoke emission was increased as injection timing was retarded due to the increased locally rich area in the high ambient pressure. NOx emission showed decreasing trend as injection timing was retarded. This is likely due to the maximum in-cylinder temperature was decreased with retarded combustion phase.