Abstract: An internal combustion engine includes a cylinder head with an exhaust manifold configured to supply exhaust gas through a main exhaust outlet to a main exhaust aftertreatment system having a main catalytic converter, a bypass passage in fluid communication with the exhaust manifold via a bypass port, a bypass catalytic converter disposed within the bypass passage, and a dual-acting valve assembly configured to move between a first position that seals the bypass port, and a second position that seals the main exhaust outlet. During cold start, long idle, and/or low main catalytic converter temperature conditions, the dual-active valve assembly is moved to the second position to direct exhaust flow through the bypass passage and the bypass catalytic converter to reduce emissions.

Abstract: A cylinder head assembly for an internal combustion engine includes a cast cylinder head, a turbocharger housing including a compressor housing and turbine housing integrally cast with the cylinder head, and a turbocharger cartridge assembly configured to be inserted into the turbocharger housing and including a shaft coupled between a compressor wheel and a turbine wheel. A compressor cover is configured to couple to the compressor housing and define a compressor inlet and at least partially define a compressor diffuser passage. The cartridge assembly includes a housing having a diffuser flange extending outwardly therefrom, the diffuser flange including a front surface and an opposite contoured volute surface. The compressor diffuser passage is at least partially defined by the compressor cover and the diffuser flange front surface. A compressor volute is at least partially defined by the diffuser flange contoured volute surface and a contoured inner surface of the compressor housing.