1. ABSTRACTSteady flow simulations have been performed on two typical intake port shapes: a straight port and a swirl producing one. The code Star-CD was used with the standard k-ε turbulence model. For both ports, detailed comparisons with measurement data have shown good qualitative results for the discharge coefficient and velocity field in the cylinder. For the second port, the swirl coefficient computation has been largely improved by a global mesh refinement and a blended higher order discretization scheme. Due to the more complex flow structure produced, results for the straight port were found to be less sensitive to those parameters. The discharge coefficient evaluation was also slightly better.As this approach was shown to be efficient, it is now applied industrially.Sensitivity to upstream conditions is shown for particular port shapes. Correlation with the swirl measured by a paddle wheel is discussed. The swirl production mechanisms are described using several tools. By analysing these mechanisms, we improved port shape to reach a requested compromise between the discharge and the swirl coefficients.Engine torque predictions based on computed discharge coefficients correlate properly with test bench results for various cases.