There are significant geometrical as well as operational parameters which affect the emission performance of a diesel engine. In this work, various important engine variables are selected for optimization. The objective of this work is to satisfy BS III norms, that too, with a healthy margin. Among the selected variables, swirl is a complex variable to control, and that itself depends on number of geometrical and operational parameters. Chamfer angle of the valve seat is modified to vary swirl ratios, actual swirl performance test is done. Further, CFD and analytical analysis is done on various geometrical parameters of intake port and important parameters affecting swirl were identified. Thus, by the above exercise three optimum swirl ratios were selected for design of experiments. Engine variables selected for optimization are swirl ratio, fuel injection timing, nozzle orifice (K and KS type) and turbocharger (waste gate and free float). L9 Orthogonal array was formed consisting of 9 experiments, in which each variable was varied at different levels. Standard Engine Steady state Cycle (ESC) was performed for each experiment. Analytical tools of Taguchi method like Analysis of Means, Signal to Noise ratio and Analysis of Variance was applied on the obtained experimental results and an optimum setting was found. Fuel injection timing, swirl ratio and nozzle orifice were found out to be significant parameters affecting emissions. The optimum setting gave a good margin for PM, CO, HC and NOx at 20%, 65.23%, 90.9% and 9% respectively, from BS III norms.