The primary function of the intake manifold is to evenly distribute the air to each intake port in the cylinder head(s). Even distribution is important to optimize the efficiency and performance of the engine. An uneven air distribution leads to less volumetric efficiency, power loss and increased fuel consumption. There is some scope to increase the velocity of air and volumetric efficiency by change the geometry of intake manifold. In this research, it was studied about the design of intake manifold for existing design and then proposed the new design which has the performance is better than the conventional. Computational Fluid Dynamics (CFD) software is used to analyze the air flow and pressure of air inside the intake manifold especially for the plenum. According to this analysis, the proposed design is agreed to give more performance to the engine.