In this study an effort was made to develop a flow simulation modeling and performance prediction for a centrifugal compressor stage of a heavy-duty D. I. diesel engine. The model is implemented in simulation software in MATLAB language. Additionally, a contribution of this paper to demonstrate that off-design performance of a centrifugal compressor stage in a turbocharger system can be accurately simulated using commercial CFD software, with design software, FLOEFD to generate high quality meshes and model solving. The vector plots, contour plots and stream line plots are generated for better understanding of fluid flow through centrifugal compressor stage. Correlation coefficients have been introduced in the calculation program, in order to be closer to the CFD simulation results. The results obtained from mathematical computation model were validated with the CFD analysis and experimental results performed using a test bench for the variation of the performance parameters such as isentropic efficiency, power input, and total pressure ratio with mass flow rate, the results are also presented in graphical form. The results reveal that reasonable agreement between mathematical models, the numerical results obtained from the CFD simulations and the real measurements; the maximum difference never exceeds 5%. The results indicate that the developed mathematical computation model can yield better predictions of performance for a centrifugal compressor stage in a turbocharger system.