A V8 engine, each bank of which is configured such that four crank pins connected to four piston pins via a connecting rod are positioned at 90° intervals when viewed from one end of a crankshaft. The four crank pins on the bank side are offset by 60° relative to the four crank pins on the bank side when viewed from the one end.

An outboard motor to be attached to a hull of a marine vessel that reduces an amount of oil in blow-by gas reaching a breather chamber includes an internal combustion engine including a cylinder block including at least one cylinder. The cylinder block includes two blow-by gas flow paths to guide blow-by gas from a crank chamber to a breather chamber, and the internal combustion engine is oriented such that a crankshaft extends along a direction perpendicular or substantially perpendicular to a bottom of the hull when the marine vessel is sailing.

A vessel propulsion apparatus includes an engine and a propulsion unit to be driven by the engine. The engine includes a cylinder head including a combustion chamber and a pair of intake openings to communicate with the combustion chamber. The engine further includes a pair of intake ports respectively including a pair of downstream portions respectively connected to the pair of intake openings. A distance between the pair of downstream portions decreases toward the pair of intake openings.

Combustion air intake ports are provided on left and right side faces of an upper part of an engine cover. An outer louver is disposed to confront the combustion air intake port, and an inner louver is disposed inward of the outer louver at a predetermined interval to face the outer louver. The combustion air received from the combustion air intake port passes through the outer louver and the inner louver and is guided to the engine unit from the guide hole. In this case, a splash of water is dispersed in the outer louver, and a large-sized water droplet falls down due to its self-weight before the combustion air reaches the inner louver, so that a small-sized water droplet can be collected and removed using inertial impaction at the inner louver. Therefore, it is possible to effectively separate water.

An outboard motor includes a power source disposed, a propeller shaft, a drive shaft, a gear mechanism, a lower case having an internal space in which gear oil is stored, a gear oil gauge configured to check a level or a state of the gear oil stored in the internal space, a gauge mounting hole provided configured to removably mount the gear oil gauge to the lower case such that one end side of the gear oil gauge is immersed in the gear oil stored in the internal space, a gauge insertion portion configured to insert the gear oil gauge into the gauge mounting hole, an oil supply and discharge passage provided in the lower case, and a pump connecting portion configured to connect a pump. The gauge insertion portion and the pump connecting portion are arranged side by side.

A pump device includes a first case, a second case, a sacrificial anode. The first case has a channel in which hydraulic fluid flows. The second case provides in contact with the first case. The sacrificial anode is coupled to one of the first case and the second case and suppresses corrosion of the first case and the second case. At least one of the first case and the second case includes an insulating section that interrupts electric coupling between the first case and the second case. The pump device further includes a valve member provided in the channel, controlling the flow of the hydraulic fluid flowing in the channel, and electrically coupling the first case and the second case.

A cooling structure for an outboard motor comprises an oil case which has an oil chamber for storing lubricant oil for an engine. Said cooling structure further comprises: a main exhaust gas passage which guides exhaust gas to a lower side; a cooling water outbound path which guides cooling supply water taken from outside the outboard motor to an upper side, and cools the periphery of the main exhaust gas passage in the oil case by means of the cooling supply water; a cooling water inbound path which guides cooling discharge water that has cooled the engine to the lower side and cools the oil chamber by means of said cooling discharge water; and a mixed fluid passage which, on a side below the oil case, cools the exhaust gas by mixing the exhaust gas and the cooling discharge water.

Engine includes: crankcase housing crankshaft extending in vertical direction; cylinder block mounted on side of crankcase and formed with cylinder; cylinder head mounted on side of cylinder block and provided with air inlet port and air outlet port communicating with cylinder; cylinder head cover mounted on side of cylinder head and covering air inlet port and air outlet port; mount case including: supporting portion provided below crankcase and cylinder block and supporting crankcase and cylinder block; and extending portion extending from supporting portion below cylinder head and cylinder head cover; oil pan provided below mount case and storing lubricating oil; and communication tube communicating first space formed between cylinder head and cylinder head cover and second space formed between mount case and oil pan. Communication tube is provided between cylinder head cover and extending portion.

Upper anti-vibration mounts have axial lines arranged in parallel to a longitudinal center line extending in a longitudinal direction of the outboard motor body. Lower anti-vibration mounts have axial lines concentrated on one point on the longitudinal center line extending in a longitudinal direction of the outboard motor body. Meanwhile, the axial lines are inclined at the identical angle symmetrically with respect to the longitudinal center line, so that they intersect in a V-shape in front of the support shaft as seen in a plan view of the outboard motor body.

A watercraft propulsion system includes a propulsion unit to be driven by an engine. The engine includes a cylinder block, an air intake channel, an exhaust channel, a supercharging device, and a fuel injector. The watercraft propulsion system includes the engine, the propulsion unit to be driven by the engine, a rotation speed sensor to detect a rotation speed of the engine, an air intake pressure sensor to detect an air intake pressure of the engine, and a controller. The controller is configured or programmed to compute a command fuel injection amount so that the engine performs a combustion operation at an air/fuel ratio in a lean-burn range (lean-combustion range) according to the rotation speed detected by the rotation speed sensor and the air intake pressure detected by the air intake pressure sensor, and to drive the fuel injector based on the computed command fuel injection amount.