The stringent emission norms and increasing demand for engines with higher power density lead to an extensive investigation of parameters affecting combustion performance. Recent emission norms have forced the engine manufacturers to reduce the Particulate matter (PM) emissions along with other emissions substantially. In order to achieve lo PM emissions the lubrication oil consumption need to be controlled by optimizing piston group design with low liner bore distortion.Bore Distortion is the deviation of actual profile from perfect circular profile at any plane perpendicular to axis of cylinder. Liner bore distortion in engines causes' number of problems like deterioration of piston ring performance, liner-ring conformability issues, high lubricating oil consumption and emissions. Besides traditional prediction of stresses, fatigue life and verification by mechanical testing, the prediction of liner bore distortion is one of today's most important topics in crankcase structure development. Low bore distortion opens up potential for optimized piston group design.The research work focuses on analyzing the parameters affecting liner bore distortion in DI Diesel engines. The study has been carried out on direct injection diesel engine of heavy duty off-highway application with top hung liner. The effects of variation in gasket thickness, liner thickness, number of cylinder head bolts and bolt pre load on liner bore distortion are analyzed successfully.Firstly, a FEA model of crankcase-liner-cylinder head assembly has been developed and the bore distortion results are compared with actual measurements on engine. An extensive analysis has been carried out to study effect of four parameters considered on liner bore distortion. Thus the present research work helps to bridge the gap between understanding the effect of these parameters on liner bore distortion occurrence, lube oil consumption and hence PM emissions.