An intake system component for an internal combustion engine includes a tubular curved portion extending in a curved manner. The curved portion includes an inner wall located on an inner side of a curve relative to an inner passage. The inner wall is made of a breathable fibrous molded body. A part of the curved portion excluding the inner wall includes a portion having a lower breathability than the inner wall.

A positive crankcase ventilation system for an internal combustion engine routes blowby gases into the intake of the engine. Because the blowby gases have about 12% water vapor, during cold-weather operation, the water vapor may freeze in the PCV valve or in the port that couples the PCV duct with the intake manifold. In situations in which the PCV duct is pointing toward the direction of flow of the intake gases, a hood or cap is placed over the end of the tube according to the present disclosure. It can be as simple as a 90-degree elbow or multiple openings in the cap. A centerline of the openings is perpendicular or at an obtuse angle with respect to the direction of flow in the duct so that the intake gases do not directly access the openings and cause freezing in the openings (or ports).

A family of manifolds for a family of engines. A first and second engine respectively have a first and second number of cylinders. The second number is at least one and smaller than the first number. Each manifold has a plenum chamber and an inlet. The first and second manifolds respectively have the first and second number of outlets, each connected to one of a first number of runner passages. The first manifold is manufactured by inserting an outlet insert for forming at least one of the first number of outlets into a first or second mold, forming a first portion thereof using the first mold, forming a second portion thereof using the second mold, and connecting the portions. The second manifold is manufactured by forming a first portion thereof using the first mold, forming a second portion thereof using the second mold, and connecting the portions.

An intake manifold made of synthetic resin includes first, second and third members stacked in sequence and welded to form the intake manifold; a collector extending inside the intake manifold in a direction of a line of cylinders, a part of wall of the collector being formed by the third member; a plurality of branch passages formed substantially by the first and second members and wound around an outer periphery of the collector; and a connector passage leading from the collector to an outer peripheral side of the branch passage. The first, second and third members are respectively provided with first, second and third cylinder portions that are coaxially arranged with each other in a position between adjacent two branch passages. The connector passage is formed by the first, second and third cylinder portions with the connector passage communicating with an inside space of the collector.

A modular intake manifold for a V-style motor cycle engine is configured to interface with manifold ports on cylinder heads of a first engine and with manifold ports on cylinder heads of a second engine. The first engine has cylinders of a first length, and the second engine has cylinders of a second length larger than the first length. The manifold port of each cylinder head of the first engine is offset from the centerline of the respective cylinder bore by a first offset distance. The manifold port of each cylinder head of the second engine is offset from the centerline of the respective cylinder bore by a second offset distance that is greater than the first offset distance. A method includes manufacturing the first cylinder and second cylinders, the first and second cylinder heads, and the intake manifold with the respective same considerations.

A duct includes a circumferential wall. At least part of the circumferential wall is a fibrous portion that includes fibers. The fibrous portion includes a breathable inner layer located on an inner circumferential side in the circumferential wall and an outer layer located on an outer circumferential side of the inner layer in the circumferential wall. The outer layer is less breathable than the inner layer. A boundary between the inner layer and the outer layer is breathable.

The disclosure relates to an air inlet system for an internal combustion engine. The air inlet system has a cylinder head having an inlet channel for introducing inlet air into a combustion chamber of the internal combustion engine. The air inlet system has an air supply pipe piece, which is connected to the cylinder head and which at least partially forms an air supply channel, which opens in the inlet channel. The air inlet system additionally has thermal insulation, which is arranged in the air supply channel in order to reduce a heat transfer to the inlet air which flows in the air supply channel.

An air intake duct (50) for a motorcycle supplies air taken in through an air inlet (24) in a front portion of a vehicle body to an engine (E) located at a center portion, in a longitudinal direction of the motorcycle, of the vehicle body. The air intake duct (50) includes a duct front (69) having the air inlet (24) formed at a front end thereof, and a duct body (70) removably coupled to a rear end portion of the duct front (69). The duct body (70) extends in the longitudinal direction so as to pass through an outer lateral side of the engine (E) and is removably connected at a rear end portion thereof to an air cleaner (40). In a state in which the duct body (70) is removed from the air cleaner (40), a cleaner element (87) can be attached and removed.

An inlet duct for an internal combustion engine includes a duct member made of a compression molded fiber material. The duct member includes a main body and end portions provided on opposite sides in an axial direction of the main body. The main body includes at least one high-compression portion and at least one low-compression portion, which is made through compression molding at a compression ratio lower than that of the at least one high-compression portion. The at least one low-compression portion extends throughout a length in the axial direction of the main body.

In an intake manifold that has charge-motion-control valves (CMCVs), a gap exists between the flapper valves and the wall of the intake runners. Although the gap is maintained as small as practical, it cannot be eliminated because manufacturing tolerances and temperature variations to which the intake manifold is subjected must be accommodated to prevent binding of the flapper valves. Some flow makes an end run through the gap leading to undesirable fluid mechanics. Disclosed herein is a seal that is positioned to rest gently upon the flapper valve near the gap such that the gap is substantially sealed off while applying a modest force on the CMCV so that the actuation torque is minimally impacted. The seal has a press-in-place portion inserted into a pocket formed in the manifold to hold it in place and a lip portion that extends out from the press-in-place portion to obstruct the gap.