An air intake and exhaust system for a marine engine having an intake manifold and an exhaust manifold includes an air compressor configured to compress ambient air into compressed air and a catalytic converter assembly configured to convert pollutants in an exhaust gas stream received from the exhaust manifold. The air compressor is configured to be fluidly coupled to the intake manifold of the engine for directing at least a first portion of the compressed air to the intake manifold of the engine. The air compressor is also selectively fluidly coupled to the catalytic converter assembly for selectively directing a second portion of the compressed air into the exhaust gas stream at a secondary air injection location at or upstream of the catalytic converter assembly.

A heat shield includes an outer jacket including a fluid inlet port and a fluid outlet port, and an inner jacket nested within the outer jacket and spaced apart therefrom to define a fluid passageway therebetween. The fluid passageway is in fluid communication with the fluid inlet port and the fluid outlet port for directing a cooling fluid from the fluid inlet port to the fluid outlet port through the fluid passageway. The inner jacket at least partially defines a main cavity configured to at least partially protect a turbocharger of the marine engine.

An outboard motor (10) includes a V-engine (20) having a left bank (BL) and a right bank (BR) extending obliquely toward a rear left side and a rear right side, respectively, relative to a crankshaft (21) extending in a vertical direction. An intake device (18) is provided between the left bank and the right bank, and catalyst devices (62L, 62R) that treat exhaust gas are disposed rearward of cylinder heads (24L, 24R) of the left bank and the right bank.

A marine outboard motor has an internal combustion engine including an engine block, at least one cylinder, an air intake configured to deliver a flow of air to the at least one cylinder and an exhaust conduit configured to direct a flow of exhaust gas from the at least one cylinder. The internal combustion engine also includes an exhaust gas recirculation system configured to recirculate a portion of the flow of exhaust gas from the exhaust conduit to the air intake. The exhaust gas recirculation system comprises a heat exchanger for cooling recirculated exhaust gas. The heat exchanger is removably integrated into the engine block.

A marine drive includes an engine; an exhaust conduit that conveys exhaust gases from the engine to an idle relief outlet on the marine drive, wherein the idle relief outlet discharges the exhaust gases to atmosphere when the marine drive is operated at an idle speed; and an idle relief muffler having a muffler inlet that receives the exhaust gases from the exhaust conduit, a muffler outlet that discharges the exhaust gases to the idle relief exhaust outlet, and a drain for draining water from the idle relief muffler. The muffler inlet conveys exhaust gases into the idle relief muffler in a direction that is oriented away from the muffler outlet and away from the drain, such that water in the exhaust gases is encouraged to separate from the exhaust gases and then drain from the idle relief muffler via the drain.

A crankshaft lubricating oil passage structure of a V-shaped engine includes a main oil passage and a sub oil passage. The V-shaped engine includes a pair of banks. The pair of banks includes cylinders and is disposed in a V shape with respect to the crankshaft. The V bank angle as an included angle of the cylinders of the respective banks is set at a narrow angle. The main oil passage is provided between the pair of banks in the cylinder block or the crankcase. The sub oil passage extends from the main oil passage to the bearing portion of the crankshaft and guides lubricating oil to the bearing portion. The main oil passage is formed by connecting divided passage portions that are divided partway in an axial direction by an oil passage connection member that is a separate member from the cylinder block or the crankcase.

An outboard motor that significantly reduces or prevents discoloration around an exhaust opening includes an engine, a drive shaft, a propeller shaft, a housing, an exhaust passage, a water intake passage, and a valve. The exhaust passage guides an exhaust gas from the engine toward the discharge chamber inside the housing. The water intake passage guides water, which enters an inside of the housing, to the discharge chamber when a forward propulsive force is generated. The valve regulates passage of the exhaust gas at the first opening due to water pressure when a forward propulsive force is generated. The valve permits the passage of exhaust gas at the first opening due to exhaust pressure when a backward propulsive force is generated.

Constraints on arrangement of catalysts are reduced, and early activation and long-term performance maintenance of the catalysts are both achieved. An exhaust pipe includes a first catalyst provided in a first exhaust pipe extending upward on the side of an exhaust manifold, and a second catalyst provided in a second exhaust pipe that extends downward from a bent pipe extending from the first exhaust pipe and that is adjacent to the first exhaust pipe. The second catalyst is disposed at a position offset to a higher location from an up-down middle position of the first exhaust pipe.

A propulsion system has an internal combustion engine including an exhaust manifold and an engine air intake, an exhaust port fluidly connected to the exhaust manifold, a fresh air intake fluidly connected to the engine air intake and a filter assembly including adsorbent material and being configurable between a loading configuration allowing for filtration of at least some components of an exhaust gas of the engine, and a purging configuration allowing for removal therefrom of at least some of the components of the exhaust gas. In the loading configuration, the filter assembly is fluidly connected between the exhaust manifold and the exhaust port. In the purging configuration, the filter assembly is fluidly connected between the fresh air intake and the engine air intake. Above a threshold effective engine speed of the engine, the filter assembly is in the purging configuration. A method for treating exhaust gas is also described.

A marine propulsion system configured to propel a marine vessel in a body of water. The marine propulsion system includes an engine and an exhaust system that conveys exhaust gas from the engine. A controller controls the marine propulsion system and includes a memory module that stores operating modes with corresponding sound profiles for controlling the marine propulsion system. An input device is provided for selecting one of the operating modes for controlling the marine propulsion system. Selecting a first operating mode causes the marine propulsion system to sound different than selecting a second operating mode.