A valve bridge to operatively interface with a rocker arm and a valve, and systems, assemblies, and methods thereof can comprise: a body, of the valve bridge, having a first side and a second side opposite the first side, a first leg of the valve bridge extending from the first side of the body, a second leg of the valve bridge extending from the first side of the body, and a third leg of the valve bridge extending from the first side of the body. A first pin can extend from an end of the first leg opposite the body, and a second pin can extend from an end of the second leg opposite the body.

In a spark-ignition internal combustion engine in which a protrusion including an intake-side inclined surface and an exhaust-side inclined surface is formed on a top surface of a piston, and a cavity is formed in the protrusion at a position associated with a spark plug, the intake-side inclined surface and the exhaust-side inclined surface are formed in such a way that a ratio of a length of the exhaust-side inclined surface with respect to a length of the intake-side inclined surface is 1.25 or larger in a cross section passing through a center axis of the piston and orthogonal to an axis direction of a crankshaft.

A guiding portion of an intake valve head includes a specific tangent line, which, when the intake valve is in a fully open state, intersects with at least one selected from an ignition plug and a closed exhaust valve. A line segment that agrees with a tangent line contacting the guiding portion and extends from a contact point of the tangent line with the guiding portion to an intersection point of the tangent line with a central axis of the head is defined as a first line segment, a line segment that agrees with the central axis and extends from the intersection point toward the intake passage is defined as a second line segment, and an angle formed by the first second line segments is defined as a specific angle. The tangent line that minimizes the specific angle is the specific tangent line.

A method for manufacturing a cylinder head includes: preparing a cylinder head casting having an intake passage, an exhaust passage, and a combustion chamber by casting using a mold and a plurality of cores; machining an intake port, an intake valve seat, an intake valve guide bore, an exhaust port, an exhaust valve seat, and an exhaust valve guide bore in the cylinder head casting by a first cylindrical tool; and forming a tapered surface on a portion of edge of the intake port by a second cylindrical tool. In particular, the second cylindrical tool moves along a predetermined trajectory at the edge portion of the intake port and rotates around an axis simultaneously to machine the tapered surface.

An internal combustion engine includes: a crankshaft supported via a bearing; a balancer drive gear ; a balancer shaft; and a one-way clutch mechanism that transmits to the crankshaft a drive force to start the internal combustion engine. In the internal combustion engine, the bearing includes an oil seal built therein, the oil seal sealing a crank chamber of the crankcase. The one-way clutch mechanism includes a case fixed to the crankshaft and a starter driven gear provided relatively rotatably with respect to the case and driven by the drive force. The starter driven gear includes a thrust bearing portion that abuts on the balancer drive gear in an axial direction of the crankshaft.

An in-cylinder injection engine includes: a cylinder head that includes a gasket surface stacked on a seating face of a cylinder block and defines a combustion chamber between a piston and a ceiling surface gradually receding from an imaginary plane including the gasket surface in going toward a center of the cylinder head; two intake ports disposed side by side and opened in the ceiling surface of the cylinder head; and a fuel injection valve mounted to the cylinder head and having an injection port facing the combustion chamber at a position between an opening of the intake port and the gasket surface. The intake port is formed to have a shape of introducing an airflow laterally into the combustion chamber along the imaginary plane. Accordingly, the in-cylinder injection engine can reduce attachment of injected fuel to a wall surface of a cylinder bore.

A rotational combustion engine that generates force from the reciprocal motion and centripetal motion of one or more pistons that is then converted into rotational motion of a first cam and second cam wherein the cams are separated by a 2-3 degree horizontal offset and an angle of 60 degrees as well as camshaft assembly and driving shaft to provide power to an entity such as an automobile.

A cylinder head for an internal combustion engine, includes: first and second valves being intake valves or exhaust valves; a first circumferential wall portion defining a first port, the first port being opened and closed by the first valve and communicating with a combustion chamber; and a first overlay welded portion formed on the first circumferential wall portion and serving as a first valve seat on which the first valve is seated.

In an internal combustion engine in which a plurality of cylinders are arranged in series in a cylinder section, pressures of the cylinders can be detected by a smaller number of pressure sensors. An engine in which a plurality of cylinders are arranged in series in a cylinder section includes a communication path through which combustion chambers of the cylinders adjacent to each other communicate with each other, and a pressure sensor is disposed in the communication path.

A pushrod valvetrain combustion system assembly for an internal combustion engine includes a two-valve pushrod assembly and a cylinder top that forms a portion of a cylinder head. The cylinder top has a single intake port, a single exhaust port, a spark plug bore, and a fuel injector bore. The pushrod assembly includes an intake valve positioned in the intake port and an exhaust valve positioned in the exhaust port. The intake port and exhaust port are positioned adjacent each other and are positioned along an axis that intersects a center point of each of the ports. The intersecting axis is rotated relative to a centerline of the crankshaft of the engine, providing space for the spark plug bore and fuel injector bore to both be located in the cylinder top on a same side of the intersecting axis.