Abstract: A turbocharger includes a turbine housing. The turbine housing includes a turbine inlet wall defining an inlet passage, an exducer shroud wall defining an exducer interior, a turbine outlet wall defining an outlet passage, a wastegate port wall defining a wastegate channel, and a bushing wall coupled to the wastegate port wall and defining a bushing boss extending along a bushing axis, and a valve seat disposed about the wastegate channel. The turbocharger also includes a wastegate assembly. The wastegate assembly includes a valve element engageable with the valve seat. The wastegate port wall is disposed outside of the exducer interior such that the wastegate port wall and the bushing wall are configured to be thermally decoupled from the turbine inlet wall and such that relative displacement between the valve seat and the bushing axis is reduced during operation of the turbocharger.

Abstract: An asymmetric twin scroll turbine 10 combined with an integrated exhaust manifold cylinder head 20 may be designed to accommodate mixed, radial or axial flow turbines. The asymmetric twin scroll turbine 10 includes a first scroll 11 and second scroll 12 wherein the first scroll 11 is larger and has greater mass flow capacity than the second scroll 12. The larger volute increases flow capacity and counteracts backpressure creating evenly balanced or equalized peak pressures and pulsations between both volutes and balancing of gas flow between cylinder sets. By equalizing peak pressures, pulsations, and gas flow between cylinder sets, engine self-ignition can be avoided in the cylinder set that would have had the largest peak pressures and pulsations. By in creasing flow capacity of the larger volute and balancing gas flow between cylinder sets, the turbine pressure differential is reduced and the engine can operate more efficiently, improving fuel economy.