In general, the design of intake manifold (IM) for Otto cycle engines starts with one-dimensional (1D) gas dynamics simulation which is used to define its main characteristics. The use of unsteady CFD (Computer Flow Dynamics) methodology can provide additional information not captured in 1D method, allowing a greater optimization of the IM geometry. Due to dynamic boundary conditions involved, this type of analysis increases significantly the results making the compilation more difficult and time consuming (1). This paper presents a methodology for unsteady simulation where qualitative results may provide a direction at an early stage in the design process. Examples and practical results already implemented are discussed to guide designers through IM development.