Various methods and systems are provided for an intake manifold for an engine. In one example, an insert comprises an annular body having a top surface, bottom surface, inner surface, and outer surface. The insert further comprises a first groove for coupling an intake air port of an intake manifold to a cylinder head, a second groove for circulating gaseous fuel received from a gas runner of the intake manifold, and one or more openings to fluidically couple the second groove to an interior of the intake air port. The insert is configured to mix gaseous fuel and intake air at a coupling location between the intake manifold and the cylinder head.

An off-road vehicle includes an air intake system that comprises an opening that, in operation, receives air, and an exhaust system that includes an exhaust stack positioned in the opening of the air intake system.

A cover covering an engine and an intake duct for introducing fresh air outside an engine room into a combustion chamber of the engine are provided in the engine room. The cover includes a top face cover portion covering the engine from above, and a side face cover portion covering the engine from the lateral side. The intake duct is disposed so as to be continuous to a side edge of the side face cover portion such that the intake duct covers the engine from the lateral side together with the side face cover portion.

A cylinder head for an internal combustion engine is disclosed having an intake port geometry configured to reduce fuel puddling and improve fuel atomization. The cylinder head includes a housing having a recess defining a top portion of a combustion chamber. The cylinder head further includes intake and exhaust ports defined by channels extending from the top portion of the combustion chamber to an outer end of the housing. An intake valve is positioned within the cylinder head to control communication of the intake port with the combustion chamber, and an exhaust valve is positioned within the cylinder head to control communication of the exhaust port with the combustion chamber. The intake port further includes a cross-section having a modified D-shape with a single 90 degree corner. The modified D-shape cross-section extends substantially a length of the intake port.

An intake manifold is provided and includes a runner that is connected between a plenum and a cylinder head to allow air introduced into the plenum to enter the cylinder head. A dent is formed at the runner such that the dent extends along a channel of the runner while having an inner surface with a protruding shape. The runner has, at an end thereof, an inner surface formed to be flat without being formed with the dent. The inner surface of the runner is connected to the cylinder head.

A saddle type vehicle to improve the workability in fastening a frame and an engine together and thereby to enhance productivity. The saddle type vehicle includes a head pipe, a main frame extending rearwardly from the head pipe, and a seat rail located rearwardly of the main frame for supporting a seat. The main frame is fastened to the engine by fastening members being directed from an outer side toward an inner side in the vehicle widthwise direction. A knock pin is provided between the main frame and the engine, in a position in the vicinity of at least one of the fastening members.

An intake apparatus of a V-type internal combustion engine including first cylinders arranged along a first direction in a first bank and second cylinders arranged along the first direction in a second bank, the intake apparatus includes a surge tank, first branch paths, second branch paths, and a protrusion. The surge tank is provided above the first and second banks. The surge tank includes a lower wall, an air inlet, first air outlets, and second air outlets. The first air outlets are arranged along the first direction in the lower wall. The second air outlets are arranged along the first direction in the lower wall. The first branch paths connect the first outlets to the first cylinders. The second branch paths connect the second outlets to the second cylinders. The protrusion is provided on the lower wall between a closest first air outlet and a closest second air outlet.

A heat storage cover is provided in an engine room. The heat storage cover covers an engine from above and surrounds the periphery of an upper portion of the engine to internally store, through the medium of air, heat dissipated from the engine and block upward heat dissipation. The engine includes an air inlet for introducing, into a combustion chamber, high temperature air obtained by the heat storage cover blocking the upward heat dissipation.

A vehicle includes an engine, an engine cover, and a cross component. The engine cover has a through-hole through which the cross component passes. The cross component is a flexible hose or a flexible pipe in which a body part extending in a cross direction is integrated with a diameter enlarged part having a diameter larger than the body part. The outer peripheral part of the diameter enlarged part makes close contact with the inner peripheral surface of the through-hole of the engine cover.

A heat exchanger arrangement is provided with a housing provided with a fluid inlet and a fluid outlet and designed to be flowed through by the fluid. A heat exchanger is arranged in the housing between fluid inlet and fluid outlet and surrounded by the housing. The heat exchanger is arranged such that the fluid can flow through the heat exchanger. The housing has a seal contour. The heat exchanger is connected with form fit at a fluid inlet of the heat exchanger or at a fluid outlet of the heat exchanger to the seal contour of the housing. In a method of producing the heat exchanger arrangement, a seal surface of the seal contour of the housing is melted and pressed against a seal region of the heat exchanger at the fluid inlet of the heat exchanger or at the fluid outlet of the heat exchanger.