An exhaust port liner, which may include a superalloy and may be manufactured by an additive manufacturing process, includes a monolithic structure including an outlet disposed an angle relative to an inlet, and a sidewall defining a cavity to provide enhanced thermal performance in reciprocating internal combustion engines. A cylinder head of an internal combustion engine may include a cylinder head frame, and the exhaust port liner may be disposed proximate the frame inner mounting surface, with an outer surface of the exhaust port liner conforming to an inner mounting surface of the cylinder head frame.

An actively cooled air cylinder for a motorcycle engine comprising a cylinder block. The cylinder block may comprise an upper mounting surface, a lower mounding surface, an internal bore extending between the upper mounting surface and the lower mounting surface, a forward facing surface, a rear facing surface, and first and second side surfaces. Each of the surfaces may comprise a plurality of fins and a plurality of cooling channels located between each of the plurality of fins. The cooling channels may comprise a series of peaks and valleys that configured provide turbulent flow of air over the cylinder block when airflow contacts the cylinder.

An actively cooled air cylinder for a motorcycle engine comprising a cylinder block. The cylinder block may comprise an upper mounting surface, a lower mounding surface, an internal bore extending between the upper mounting surface and the lower mounting surface, a forward facing surface, a rear facing surface, and first and second side surfaces. Each of the surfaces may comprise a plurality of fins and a plurality of cooling channels located between each of the plurality of fins. The cooling channels may comprise a series of peaks and valleys that configured provide turbulent flow of air over the cylinder block when airflow contacts the cylinder.

Provided is an engine with a starter valve arranged in a compact space and with a cylinder head having a cooling water passage and a starter valve feeding compressed air to a combustion chamber. The starter valve is arranged parallel in the axial direction to a cylinder while fitted into a sleeve, and a portion of the cooling water passage is formed by the outer surface of the sleeve fitted into a starter valve insertion hole formed in the cylinder head. A starting air passage orthogonal to the axial direction of the starter valve insertion hole is formed in the cylinder head, and a portion of the wall surface of the starting air passage is formed by the end surface on one side of the sleeve.

A heat exchange device includes: a first flow path through which a first fluid flows; a second flow path through which a second fluid flows, the second flow path being separated from the first flow path by a tubular partition wall and positioned close to an outer circumference of the tubular partition wall; an offset fin installed in a tubular shape extending along an inner circumferential surface of the tubular partition wall; and a pressing member disposed inward of the offset fin such that the offset fin is pressed toward the inner circumferential surface of the partition wall while being elastically deformed. The offset fin is provided with a plurality of wave-shaped portions arranged in an axial direction of the tubular partition wall and positions of wave-shapes of the wave-shaped portions adjacent to each other are offset from each other in a circumferential direction of the tubular partition wall.

A heat exchange device includes: a first flow path through which a first fluid flows; a second flow path through which a second fluid flows, the second flow path being separated from the first flow path by a tubular partition wall and positioned close to an outer circumference of the tubular partition wall; an offset fin installed in a tubular shape extending along an inner circumferential surface of the tubular partition wall; and a pressing member disposed inward of the offset fin such that the offset fin is pressed toward the inner circumferential surface of the partition wall while being elastically deformed. The offset fin is provided with a plurality of wave-shaped portions arranged in an axial direction of the tubular partition wall and positions of wave-shapes of the wave-shaped portions adjacent to each other are offset from each other in a circumferential direction of the tubular partition wall.