This paper describes a Computational Fluid Dynamics (CFD) technique for evaluating the effectiveness of an intake manifold/ EGR system. The effectiveness of the intake manifold is defined in terms of equal distribution of EGR to individual cylinders. The procedure described in this work is unparalleled, since the available testing techniques are inadequate to make measurements of the actual EGR distribution. This paper also outlines a 1D - 3D coupling approach to apply transient boundary conditions on the CFD model.As part of this study, the development of an intake manifold/ EGR system is described under different operating conditions. Different intake manifold designs are also compared. Various parameters affecting the distribution of the EGR are discussed.