CFD analysys with automatically generated mesh has been carried out by tetrahedral cells. This type of Computational Fluid Dynamics (CFD) method requires larger number of cells compared to those based on hexahedral cells. Also its cell arrangement on the wall is important to get correct wall friction effect in case wall function model is used.The purpose of this study is to investigate the influence of tetrahedral and prismatic cell size and thickness on the pressure loss and the heat transfer coefficient in the case of engine intake duct and coolant flow CFD. We found the prismatic cell thickness and layer number on wall has improved Y+ distribution and pressure drop accuracy at intake duct. Also heat transfer coefficient of coolant flow simulation accyracy is improved.We carried out automatic mesh generation and high speed computing by Windows personal computer. For example, mesh generation time with prismatic element of 1.8 million cells is finished in 2 hours by Pentium III 550MHz. Flow analysis time is about 17 hours within 200 MB memory. Also we compared commercial CFD codes to invesigate which code is suitable for practical use as design tool to shorten lead time and to reduce cost.