The combat car used the heavy duty diesel engine must have a large output for maintaining excellent mobility. The compacted graphite iron (CGI) is a material currently under study for the heavy duty diesel engine demanded for high torque, durability, stiffness, fatigue. In this study, three dimensional finite element model of a heavy-duty diesel engine was developed to conduct the stress analysis by using property of CGI. The use of CGI property on the FE model was expected to result in improved distribution of distortions and stresses. The loading conditions of engine are assembly load and operational gas load.