The present application relates to rib structure on cylinder block. A cylinder block having a top surface, an inner bottom surface, a cylinder opening on the top surface, and a head boss positioned on the top surface, centered on a first axis, and configured to engage with a fastener at an initial position, which defines a first depth. The cylinder block includes a first main boss positioned on the inner bottom surface, centered on a second axis, and configured to engage with a first main fastener at a first end position, which defines a second depth. The cylinder block includes a second main boss positioned on the inner bottom surface and configured to engage with a second main fastener at a second end position, which defines a third depth. The cylinder block includes a first rib path extending from the first depth to the second depth and a second rib path extending from the first depth to the third depth.

An engine device in which exhaust pipes and an intake pipe can be mounted highly rigidly by using an upper face corner of a cylinder block in an engine, and a support structure of the exhaust pipes and the intake pipe can be simplified. In an engine device in which a first supercharger and a second supercharger are disposed in series on an exhaust gas discharge path of an engine, the engine device has a structure in which the first supercharger and the second supercharger are disposed to be divided on opposed side faces of the engine, and an upper side exhaust pipe between the engine and the first supercharger, a lower side exhaust pipe between the first supercharger and the second supercharger, and an intake pipe between the first supercharger and the second supercharger extend to be substantially flush with one another at a head-cover disposed-height of an upper face of the engine.

A device for rotatable mounting of a camshaft of an internal combustion engine. The device includes a first bearing body with a receiver for rotatable mounting of the camshaft. The device has a cylinder head or a fixing frame for fixing the first bearing body. The device has a first fixing means which fixes the first bearing body to the cylinder head or fixing frame. The first fixing means is the sole fixing means which fixes the first bearing body to the cylinder head or fixing frame.

An engine power unit includes a crankcase, a cylinder body, and a cylinder head sequentially stacked and fastened with each other. A cam shaft holder is fastened to the cylinder head to rotatably support a cam shaft of an engine valve operating mechanism. A cylinder head cover covers the cylinder head and the cam shaft holder. Fastening bolts penetrate the cylinder head cover and the cam shaft holder to be screwed into the cylinder head. Pressing surfaces are formed on the inner surface of the cylinder head cover. The pressing surfaces are abutted against and press the cam shaft holder to the cylinder head. Thus, rigidity around the cylinder head is enhanced, and a weight reduction of the power unit is achieved.

A method for manufacturing an engine block is disclosed. In embodiments, the method includes forming an expansion hole in a block body of the engine block that encircles an engine block bore at a head face of the engine block. The method also includes placing an insert into the expansion hole, the insert including an insert body. The method further includes placing a reaction material between the insert and the block body. The method yet further includes forming an insert bond layer between the insert and block body using the reaction material. The method still further includes forming an insert bore through the insert body.

An internal combustion engine for a motorcycle includes a rear cylinder head, the rear cylinder head being provided with a camshaft, an exhaust rocker arm rocked by the camshaft, an engine valve closed/opened by being push-pressed by the exhaust rocker arm, and a rocker arm shaft swingably supporting the exhaust rocker arm. In the internal combustion engine for the motorcycle, the rear cylinder head is provided separately from a holder member, the holder member being provided adjacently to the rear cylinder head, the camshaft is rotatably supported by the holder member, and the holder member is provided with right and left rear side walls and internal combustion engine supporting portions, the right and left rear side walls supporting the rocker arm shaft, the internal combustion engine supporting portion being supported by a vehicle body frame.

Methods and systems are provided for a ventilation arrangement. In one example, a system may include a compact ventilation arrangement arranged within a space between an intake manifold and a cylinder head. A pump of the ventilation arrangement arrange adjacent the cylinder head.

There is provided a variable valve timing system including: an intake side camshaft and an exhaust side camshaft disposed on a cylinder head; and a variable valve device attached to one end portion of the intake side camshaft. The accommodating wall on an exhaust side of the cylinder head is positioned more inward in a vehicle width direction than the accommodating wall on an intake side of the cylinder head. A first bolt for fixing the intake side of the cylinder head to a cylinder is disposed more inward in the vehicle width direction than the accommodating wall on the intake side. A second bolt for fixing the exhaust side of the cylinder head to the cylinder is disposed more outward in the vehicle width direction than the accommodating wall on the exhaust side.

An engine and a method of forming an engine are provided. The engine has a block that defines a cooling jacket extending continuously about an outer perimeter of first and second siamesed cylinders. The block defines a series of head bolt bores intersecting a deck face such that each cylinder is surrounded by four bores. The jacket has a first floor and a second floor. The second floor is offset above the first floor and extends along an intake side of the block between midpoints of the first and second cylinders, respectively. The second floor is configured to decouple a relationship between the cooling jacket and the series of bores for each cylinder and reduce fourth order bore distortion for each cylinder.

A camshaft module may include a module body in which at least one camshaft for controlling valves for a charge cycle of an internal combustion engine is accommodated. The camshaft may comprise a support shaft and sliding cam pieces that are accommodated on the support shaft so as to be displaceable in an axial direction of the support shaft. A support element may also be provided on which actuators for the axial displacement of the sliding cam pieces are accommodated. The support element may extend in the axial direction and therefore parallel to the support shaft. In some cases, a coefficient of thermal expansion of the support element substantially corresponds to a coefficient of thermal expansion of the support shaft.