In this paper, the authors built a three-dimensional model by applying reverse engineering techniques on targeting the intake port of 2900cc diesel engine before that three-dimensional design technique is applied, and predicted the performance of the intake port through the flow analysis. For each valve lift, flow simulation has been carried out to confirm both swirl and tumble flow in the cylinder. Maximum velocity has been occurred between a valve head and a seat-ring regardless of valve lift. As valve lift increases, swirl velocity increases and pressure decreases at the cylinder center. This reverse-engineered model could be used to calculate the flow coefficient and swirl number.