A water cooled engine is provided, including a cylinder head with minimized thermal strain. A head water jacket includes an inter-exhaust-port-wall water channel between a first exhaust entrance port wall and a second exhaust entrance port wall. The cylinder head includes a cooling water injection passage provided at a bottom wall thereof. The cooling water injection passage is positioned on the exhaust end side, and includes a passage entrance provided on the exhaust end side, and a passage exit directed toward the inter-exhaust-port-wall water channel. An exhaust port wall includes a heat dissipation fin extending from a first exhaust entrance port wall toward an exhaust end. The space between the heat dissipation fin and a second exhaust entrance port wall forms a water channel entrance of the inter-exhaust-port-wall water channel.

A water cooled engine is provided, including a cylinder head with minimized thermal strain. A head water jacket includes an inter-exhaust-port-wall water channel between a first exhaust entrance port wall and a second exhaust entrance port wall. The cylinder head includes a cooling water injection passage provided at a bottom wall thereof. The cooling water injection passage is positioned on the exhaust end side, and includes a passage entrance provided on the exhaust end side, and a passage exit directed toward the inter-exhaust-port-wall water channel. An exhaust port wall includes a heat dissipation fin extending from a first exhaust entrance port wall toward an exhaust end. The space between the heat dissipation fin and a second exhaust entrance port wall forms a water channel entrance of the inter-exhaust-port-wall water channel.

A water jacket of an engine may include: a block-side water jacket formed in a cylinder block of the engine and surrounding a cylinder of the cylinder block; and a head-side water jacket formed in a cylinder head of the engine and surrounding a combustion chamber and an exhaust port of the cylinder head. In particular, the head-side water jacket includes: a first coolant passage surrounding the combustion chamber of the cylinder head, and a second coolant passage surrounding the exhaust port of the cylinder head, and the second coolant passage is fluidly separated from the first coolant passage.

The present invention relates to a liquid-cooled internal combustion engine comprising an engine block, which includes a plurality of cylinders, and cylinder heads closing the cylinders, wherein each cylinder is surrounded by a respective cooling liner and each cylinder head has provided therein at least one separate cooling chamber connected to the cooling liner of the associated cylinder via at least one transition channel, wherein the transition channels of at least two cylinders are interconnected via a pressure compensation chamber.

The present invention relates to a liquid-cooled internal combustion engine comprising an engine block, which includes a plurality of cylinders, and cylinder heads closing the cylinders, wherein each cylinder is surrounded by a respective cooling liner and each cylinder head has provided therein at least one separate cooling chamber connected to the cooling liner of the associated cylinder via at least one transition channel, wherein the transition channels of at least two cylinders are interconnected via a pressure compensation chamber.

A modular engine is provided in which cylinder heads and camshaft carriers with different attributes can be interchanged with one another that allows for an engine head assembly to be put together for achieving various desired characteristics without the need to replace the entire engine or redesign a new engine.

A cylinder head comprises a cylinder head body. The cylinder head body has two intake ports placed on a first side of the cylinder head body with respect to the plug hole, and the two exhaust ports placed on a second side of the cylinder head body with respect to the plug hole. A water jacket of the cylinder head includes: an intake-port-to-intake-port passage portion communicating with the outside of the cylinder head and extending between the two intake ports; an exhaust-port-to-exhaust-port passage portion communicating with the outside of the cylinder head and extending between the two exhaust ports; and a central passage portion communicating with the intake-port-to-intake-port passage portion and the exhaust-port-to-exhaust-port passage portion, the central passage portion being formed so as to surround the plug hole.

A cylinder head comprises a cylinder head body. The cylinder head body has two intake ports placed on a first side of the cylinder head body with respect to the plug hole, and the two exhaust ports placed on a second side of the cylinder head body with respect to the plug hole. A water jacket of the cylinder head includes: an intake-port-to-intake-port passage portion communicating with the outside of the cylinder head and extending between the two intake ports; an exhaust-port-to-exhaust-port passage portion communicating with the outside of the cylinder head and extending between the two exhaust ports; and a central passage portion communicating with the intake-port-to-intake-port passage portion and the exhaust-port-to-exhaust-port passage portion, the central passage portion being formed so as to surround the plug hole.

An internal combustion engine includes cylinders, a cylinder head that includes a pair of intake ports and a pair of exhaust ports for each of the cylinders, and a cylinder block that includes a block-side coolant passage. One of the pair of intake ports and the pair of exhaust ports is a pair of specified ports. The cylinder head includes an inter-port coolant passage between the specified ports. The inter-port coolant passage is connected to the block-side coolant passage through a communication portion. A flow direction is a direction in which the coolant flows in a portion of the block-side coolant passage that is connected to the communication portion. A center of a passage cross section of the communication portion is shifted to a downstream side in the flow direction with respect to a center of a passage cross section of the inter-port coolant passage.

An internal combustion engine includes cylinders, a cylinder head that includes a pair of intake ports and a pair of exhaust ports for each of the cylinders, and a cylinder block that includes a block-side coolant passage. One of the pair of intake ports and the pair of exhaust ports is a pair of specified ports. The cylinder head includes an inter-port coolant passage between the specified ports. The inter-port coolant passage is connected to the block-side coolant passage through a communication portion. A flow direction is a direction in which the coolant flows in a portion of the block-side coolant passage that is connected to the communication portion. A center of a passage cross section of the communication portion is shifted to a downstream side in the flow direction with respect to a center of a passage cross section of the inter-port coolant passage.