Exhaust system for an engine

A snowmobile comprising:

• a frame;
• at least one ski connected to the frame;
• an engine supported by the frame, the engine having an engine air inlet and an exhaust outlet;
• an exhaust pipe fluidly connected to the exhaust outlet of the engine;
• a turbocharger fluidly connected to the exhaust pipe, the turbocharger including:
• an exhaust turbine, and
• a housing housing the exhaust turbine;
• a bypass conduit disposed upstream of the housing and fluidly communicating with the housing, the bypass conduit including:
• an exhaust inlet fluidly connected to the exhaust pipe;
• and
• a flow divider for separating a flow of exhaust gas into a first exhaust flow path and a second exhaust flow path;
• a first valve disposed in the first exhaust flow path for selectively controlling the flow of exhaust gas through the turbocharger and diverting the flow of exhaust gas from the first flow path to the second flow path, the first valve being selectively movable between a first position, a second position, and at least one intermediate position between the first and second positions;
• the engine having:
• a throttle valve, and
• a throttle valve position sensor operatively connected to the throttle valve;
• and
• the first valve is selectively moved based at least on a rate of change of a throttle valve position, the rate of change being determined by the throttle valve position sensor;
• an exhaust collector fluidly connected to the housing and the bypass conduit for receiving the flow of exhaust gas therefrom, the exhaust collector including a single collector outlet;
• and
• a muffler fluidly connected to the single collector outlet,
• the first exhaust flow path being defined from the exhaust inlet to the exhaust collector, exhaust gas flowing along the first exhaust flow path passing through the exhaust inlet, then through the bypass conduit, and then into the exhaust collector,
• the second exhaust flow path being defined from the exhaust inlet to the exhaust collector, exhaust gas flowing along the second exhaust flow path passing through the exhaust inlet, then through the bypass conduit, then through the exhaust turbine, and then into the exhaust collector, exhaust gas flowing from the exhaust turbine entering and flowing through the exhaust collector directly,
• the muffler receiving the exhaust gas from both the first exhaust flow path and second exhaust flow path via the single collector outlet, exhaust gas flowing through the exhaust collector and into the muffler directly,
• in the first position of the first valve, at least a majority of the exhaust gas flowing along the first exhaust flow path,
• in the second position of the first valve, at least a majority of the exhaust gas flowing along the second exhaust flow path,
• in the at least one intermediate position, the exhaust gas flows along both of the first exhaust flow path and the second exhaust flow path.