In this study, we investigated the influence of compression ratio and injection timing on the performance, combustion, and emission profile of a six-cylinder diesel engine. We conducted a numerical analysis of the fluid dynamics using GT-Power software, covering a range of injection timing varying from 10 degrees before top dead center (BTDC) to top dead center (TDC) with 2 degree increments, and a compression ratio range from 15:1 to 19:1 in single unit increments. The results showed that starting fuel injection at a compression ratio of 19:1 and 10 degrees before top dead center resulted in a 2.95% increase in braking torque and power, while reducing specific fuel consumption by 2.87% despite the power increase. In addition, advancing the start of fuel injection relative to the baseline (4 degrees before top dead center) at a 19:1 compression ratio resulted in a 19% reduction in CO emissions and a 5.99% reduction in HC emissions. NOx emissions were lowest at a 15:1 compression ratio with retarded injection timing.

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