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 air inlet system for an internal combustion engine comprising an air inlet duct which has an upstream end including an opening and a downstream end for connection to an air flow control component and further comprising a mass air flow sensor assembly, the mass air flow sensor being located closer to the downstream end than the upstream end.

To provide a compact intake manifold which can easily and reliably hold the flame arrester (25) to the base member, the base member (21) having the flame arrester (25) incorporated therein has the recessed body portion (31) and the annular fitting holding portion (32) for fitting the flame arrester (25) in the axial direction. The fitting holding portion (32) includes an abutment surface (32a) and a fitting inner wall peripheral surface (32b). The flame arrester (25) includes a flame suppressing structure (26), an outer cylinder body (27) surrounding the flame suppression structure (26), and an elastic holder member (51) which covers the outer peripheral surface and both end faces of the outer cylindrical body (27). The elastic holder member (51) has an outer peripheral fitting portion (52) fitted to the fitting holding portion (32) while being held in close contact with the outer cylindrical body (27).

To provide an intake manifold which can reliably prevent the step from being formed in the inner wall surface of the intake passage (15) while having provided therein the fitting holding portion (32) for fitting and holding the flame arrester (25) in the axial direction, the intake manifold (10) includes a base member (21), a cover member (22) and a flame arrester (25) having a flame suppression structure. Between the flame arrester (25) and the radical stepped surface (31b) of the recessed body portion (31) is provided a retaining rectifying member (23) that prevents the flame arrester (25) from coming off with respect to the fitting holding portion (32) and forms a third inner peripheral surface (23a) continuous without a step from an opening portion on the other end side (25b) of the flame arrester (25) to the base side second inner wall surface (31c).

A sleeve structure comprises a plurality of sleeve main bodies fitted respectively into intake ports of a cylinder head of a multi-cylinder internal combustion engine and a shared base provided on one end of the plurality of sleeve main bodies. By fixing this sleeve structure to the cylinder head, an amount of labor involved in a fixing operation for fixing sleeves to a cylinder head is reduced.

The present invention provides a die assembly for molding a resin-made insert having a sleeve that is inserted into an intake port of an internal combustion engine. Each sleeve has one inlet and two outlets. The die assembly includes an inner die and an outer die. The inner die includes an inlet side part and an outlet side part. The inlet side part and the outlet side part mold an inner peripheral surface of the sleeve in an assembled state, and are removed in mutually opposite directions. By means of this assembly, a sleeve having a complicated structure and shape can be molded easily.

An air cleaner includes a housing and a filter element located within the housing. The housing includes a housing body and a fiber molding assembly. The housing body is formed by a plastic molding. The housing body has a wall located upstream of the filter element in an air flow direction and a recess, which is an inwardly recessed part of the wall. The fiber molding assembly is fixed to the wall, covers the recess from outside, and forms a part of a side wall of an inlet passage together with the recess. A communication hole for communication between the inlet passage and an interior of the housing body is formed in the recess.

An outboard marine engine comprises a crankcase; a crankshaft disposed in the crankcase and being rotatable about a crankshaft axis; a crankcase cover on the crankcase, the crankcase cover enclosing the crankshaft in the crankcase; and an air intake plenum that is integrally formed with the crankcase cover. The air intake plenum conveys intake air for combustion in the outboard marine engine.

An adaptive air intake joint for an internal combustion engine comprising a molded elastomeric duct body having standing ribs constructed and arranged to provide a continuous and sufficient contact force across the face of a joint of an adjoining duct body. A clamp secured to the duct causes the ribs to provide a continuous and sufficient contact force across a seal surface, eliminating the need for constant tension clamp and improving the air intake joint seal to prevent leakage that is especially common in cold environments.

Various methods and systems are provided for an intake manifold for an engine. In one example, the intake manifold comprises a first passage for supplying intake air to a plurality of cylinders of the engine and a second passage for supplying gaseous fuel to the plurality of cylinders.