A flow model is a convenient tool for developing the engine intake system. Two flow models for the branched engine intake were developed by the finite difference method and the method of characteristics. The results from the models were compared with the experimental data and the appropriate boundary conditions were established for each model. Modeling the flow at the intake and exhaust valves with a cylinder and at the pipe branches were the most critical part of the flow models affecting the accuracy of the solutions.
From two models, it was found that the finite difference model was simpler than the characteristic model in formulation with the better accuracy. The effects of valve timings and intake geometry were studied by the flow models to design the optimum intake system.