Abstract: An exhaust system for an engine has a volume element such as a muffler or a silencer. First and second exhaust pipes are connected as dual exhaust pipes upstream of or downstream of the volume element. The first exhaust pipe has a first length (L1). A valve is positioned in the second exhaust pipe at a distance (D) from the volume element. The distance D is a fraction of L1 such that the second pipe is a resonator for the first pipe with the valve in a closed position. A method of controlling exhaust noise includes positioning a valve in the first exhaust pipe at a distance (D) from a volume element with D being a specified fraction of a length of the second exhaust pipe, and closing the valve such that the first pipe provides a resonator for the second pipe to counteract standing wave in the second pipe.

Abstract: An exhaust system for an engine has a volume element such as a muffler or a silencer. First and second exhaust pipes are connected as dual exhaust pipes upstream of or downstream of the volume element. The first exhaust pipe has a first length (L1). A valve is positioned in the second exhaust pipe at a distance (D) from the volume element. The distance D is a fraction of L1 such that the second pipe is a resonator for the first pipe with the valve in a closed position. A method of controlling exhaust noise includes positioning a valve in the first exhaust pipe at a distance (D) from a volume element with D being a specified fraction of a length of the second exhaust pipe, and closing the valve such that the first pipe provides a resonator for the second pipe to counteract standing wave in the second pipe.

Abstract: An air induction arrangement 7 for a variable displacement engine is provided. The air induction arrangement 7 includes first and second plenums 22, 24 fluidly connected to respective first and second throttles 26, 28. The first and second throttles 26, 28 are connected to respective first and second inlets 44, 60. In partial operation, the air induction arrangement 7 induces air into the first plenum 22. In higher power demand operation, the air induction arrangement 7 additionally induces air through the second plenum 24. There is a reduction of the cancellation of acoustic output between the first and second inlets 44, 60 so that an acoustic output of the engine 14 operating with only a first group of cylinders 16 is similar to the acoustic output of the engine when the engine is operating with both groups of cylinders 16, 20.

Abstract: An air induction arrangement 7 for a variable displacement engine is provided. The air induction arrangement 7 includes first and second plenums 22, 24 fluidly connected to respective first and second throttles 26, 28. The first and second throttles 26, 28 are connected to respective first and second inlets 44, 60. In partial operation, the air induction arrangement 7 induces air into the first plenum 22. In higher power demand operation, the air induction arrangement 7 additionally induces air through the second plenum 24. There is a reduction of the cancellation of acoustic output between the first and second inlets 44, 60 so that an acoustic output of the engine 14 operating with only a first group of cylinders 16 is similar to the acoustic output of the engine when the engine is operating with both groups of cylinders 16, 20.