Cylinder head and induction system for engine

A cylinder head arrangement for an internal combustion engine comprising a cylinder head assembly having a surface for cooperation with a cylinder block having a cylinder bore in which a piston is reciprocally supported to form a combustion chamber, at least three valve seats formed in said cylinder head surface at the termination of respective intake passages for delivering an intake charge to said combustion chamber, two of said valve seats comprising side valve seats and lying at least in part on a plane containing the axis of the cylinder bore, said side valve seats lying primarily on one side of said plane, the third of said valve seats comprising a center valve seat lying generally between said side valve seats and completely on said one side of said plane, said intake passages comprising a pair of side intake passages, each serving a respective one of said side valve seats, and a center intake passage serving said center valve seat, said center intake passage being formed with a generally straight first section opening through an outer side of said cylinder head and terminating in a curved portion extending to said center intake valve seat, the upper surface of said first section adjacent and leading to said curved portion being generally planar for directing the flow generally toward the side of the intake valve seat closest to the plane and for restricting the flow therethrough and thereby increasing the velocity of the intake charge flowing therethrough, the side of said center intake passage facing the planar portion of said first section being formed with a flow restriction for reducing the flow through the side of said center intake passage, for directing the flow from said center intake valve seat toward said plane, said center intake passage being substantially smaller in cross-sectional area than at least one of said side intake passages for generating a tumble motion to the intake charge in said combustion chamber.