A cooling structure of a multi-cylinder engine is provided, which includes a water jacket formed in a cylinder block to surround cylinder bores of cylinders arranged inline, a spacer, and a coolant inlet. The spacer includes openings at positions corresponding to inter-cylinder-bore portions and a rectifying part extending outwardly on a lower side of the openings. The rectifying part inclines continuously upwardly while extending in one of an exhaust- and intake-side section of the jacket from a first end side to a second end side that is the opposite side from the first end side in a cylinder line-up direction, extending on the second end side from the one of the exhaust- and intake-side sections to the other one of the exhaust- and intake-side sections, and then extending from the second end side to the first end side in the other one of the exhaust- and intake-side sections.

A cooling structure of an engine is provided, which includes a water jacket formed in a cylinder block to surround a cylinder bore of the engine, a spacer having a vertical wall surface and inserted into the water jacket, and a coolant inlet formed in an outer wall of the water jacket, and for circulating to the water jacket coolant introduced from the coolant inlet. The vertical wall surface surrounds the cylinder bore. The spacer includes a guide part provided at a position of a lower end part of the vertical wall surface corresponding to the coolant inlet, and for guiding the coolant introduced from the coolant inlet to flow around the vertical wall surface. The guide part extends outwardly from the lower end part of the vertical wall surface toward the coolant inlet along a bottom wall of the water jacket.

A cooling structure of a multi-cylinder engine is provided, which includes a first water jacket formed in a cylinder block to surround cylinder bores of cylinders arranged inline, a spacer having a vertical wall surface and inserted into the first jacket, and a coolant inlet formed in the first jacket on a first end side in a cylinder line-up direction. The structure circulates coolant introduced from the inlet to the first jacket and a second water jacket formed in a cylinder head coupled to the cylinder block via a gasket. The spacer has a flow dividing rib extending outwardly from the vertical wall surface and for vertically dividing the coolant flow, introduced from the inlet to an intake- or exhaust-side section of the first jacket, toward the second jacket through a communication hole formed in the gasket and toward a discharging section provided to the cylinder block.

A method for operating an internal combustion engine is provided. The method includes during a first operating condition, operating two primary cylinders and two secondary cylinders to perform combustion, the two primary and secondary cylinders arranged in an inline configuration, the two primary cylinder adjacent to one another, the two secondary cylinders adjacent to one another, and the secondary cylinders positioned 175°-185° out of phase relative to the two primary cylinders and during a second operating condition, selectively deactivating the two secondary cylinders to perform combustion in only the two primary cylinders.

An engine cylinder block forms a cooling jacket adjacent to a cylinder and that intersects a deck face adapted to mate with a cylinder head. The cooling jacket has an inlet passage intersecting a mounting face adapted to mate with a coolant pump housing. The block forms a vent passage extending from the cooling jacket to the mounting face. The pump housing forms a volute adapted to receive an impeller. The housing forms a discharge passage that fluidly connects to the inlet passage of the block. The pump housing also forms a vent passage the fluidly connects with the vent passage of the block. The vent passages of the block and pump housing are positioned between the deck face of the block and the inlet and discharge passages when the pump housing is connected to the engine block.

The present invention is configured such that: a cylinder block includes an introducing portion provided at a first side of a cylinder row, cooling liquid being introduced through the introducing portion to a water jacket, a restrictor portion provided in a vicinity of the introducing portion and configured to restrict the cooling liquid, introduced through the introducing portion, from flowing to an intake-side portion of the water jacket, and a discharging portion provided at a middle portion of the cylinder row at an intake side, the cooling liquid being discharged from the water jacket through the discharging portion; and an exhaust-side portion of the water jacket is formed such that a passage cross-sectional area of a cylinder axis direction upper side of the exhaust-side portion is larger than the passage cross-sectional area of a cylinder axis direction lower side of the exhaust-side portion.

A bridge member is installed in an opening of a water jacket, and a probe of a friction stir welding tool, which rotates about an axis parallel to a cylinder axis, is pressed against a central part of an upper surface of the bridge member. The probe is kept pressed against the central part of the upper surface for a predetermined time to cause side surfaces of the bridge member to expand and come into contact with both a cylinder wall and an outer wall. The probe is moved from the central part of the upper surface to the outer wall, or the cylinder wall, while the probe is kept pressed against the upper surface, thereby friction-stir welding the outer wall, or the cylinder wall, with the bridge member to each other, and after that, the probe is removed off the top deck.

An internal combustion engine is provided. Facing pistons eliminate a cylinder head, thereby reducing heat losses through a cylinder head. Facing pistons also halve the stroke that would be required for one piston to provide the same compression ratio, and the engine can thus be run at higher revolutions per minute and produce more power. An internal sleeve valve is provided for space and other considerations. A combustion chamber size-varying mechanism allows for adjustment of the minimum size of an internal volume to increase efficiency at partial-power operation. Variable intake valve operation is used to control engine power.

An engine block has one or more bores configured for receiving one or more respective pistons; one or more coolant passages; and one or more lubricant passages. At least portions of the coolant passages and lubricant passages are disposed adjacent to and about the bores so as to cool the bores. The coolant passage portion extends over a first lengthwise portion of the bores and the lubricant passage portion extending over a second lengthwise portion of the bores. The first and second lengthwise portions are longitudinally spaced apart along the bores.

A ferritic aero diesel engine. The ferritic aero diesel engine includes an iron crankcase, a steel crankshaft and eight steel piston assemblies. The iron crankcase has a flat, horizontally opposed eight cylinder arrangement with a first set of cylinder walls defining a first set of cylinders in a first bank and a second set of cylinder walls defining a second set of cylinders in an opposed second bank. The steel crankshaft is rotatably mounted at least partially within the iron crankcase. Each of the steel piston assemblies of the plurality of steel piston assemblies is received within a respective cylinder of the iron crankcase and is coupled to the steel crankshaft. The first and second sets of cylinder walls have a minimum wall thickness of between approximately 4.8 and 5.2 mm.