An internal combustion engine includes a cylinder for combusting a mixture of fuel and air therein, and a starting air system configured to provide pressurized starting air to the cylinder and to monitor operability of the starting air system. The starting air system may include a pressurized starting air source, a starting air manifold, a starting air venting valve, and a sensing device. The pressurized starting air source is configured to store pressurized starting air. The starting air manifold is fluidly connected to the pressurized starting air source. The starting air venting valve is fluidly connected to the starting air manifold and configured to vent the starting air system. The sensing device is configured to detect a parameter that measures a condition within the starting air system.

An engine may include a cylinder having a first combustion chamber at one end thereof and a second combustion chamber at an opposing end thereof, first and second cylinder heads at an end of the first combustion chamber and the second combustion chamber, respectively, and a double-faced piston slidably mounted within the cylinder. The piston may be configured to move in a first stroke from the first end to the second end of the cylinder. The piston and the cylinder may be configured such that the first stroke includes an expansion stroke portion during which chemical energy from combustion in the first combustion chamber is converted into mechanical power of the piston, and a momentum stroke portion during which the piston continues to move to the second end of the cylinder and gases are exchanged between the first combustion chamber and a location outside the cylinder.

In a spark ignition engine, a thermal insulation thin layer is formed over a wall surface, facing an inside of a combustion chamber, of a base material forming the combustion chamber, and for a thermal conductivity [W/(m.Math.K)], a thermal diffusivity [mm.sup.2/s], and a thickness L [m] of the thermal insulation thin layer, L16.7 and L207.4().sup.0.5 are satisfied. With such a configuration, a heat loss Q_total escaping from gas in a cylinder to the wall of the combustion chamber over all strokes can be reduced, and the thermal efficiency can be improved without inducing degradation of knocking due to an increase in an amount of heating Q_intake of the gas in the cylinder during an intake stroke.

In a spark ignition engine, a thermal insulation thin layer is formed over a wall surface, facing an inside of a combustion chamber, of a base material forming the combustion chamber, and for a thermal conductivity [W/(m.Math.K)], a thermal diffusivity [mm.sup.2/s], and a thickness L [m] of the thermal insulation thin layer, L16.7 and L207.4().sup.0.5 are satisfied. With such a configuration, a heat loss Q_total escaping from gas in a cylinder to the wall of the combustion chamber over all strokes can be reduced, and the thermal efficiency can be improved without inducing degradation of knocking due to an increase in an amount of heating Q_intake of the gas in the cylinder during an intake stroke.

An intake port of an internal combustion engine is connected to a combustion chamber and includes a connecting portion having a passage cross-sectional area that increases as the connecting portion approaches the combustion chamber, and an upstream portion connected to an upstream end of the connecting portion. The connecting portion is provided at its downstream end with a valve seat with which an umbrella part of an intake valve is brought into contact. At least one recess extending in an extending direction of the intake port and included in the connecting portion and the upstream portion is provided at least at one of two portions, the two portions located on both sides in an extending direction of an output shaft, of a peripheral surface of the intake port.

An intake port of an internal combustion engine is connected to a combustion chamber and includes a connecting portion having a passage cross-sectional area that increases as the connecting portion approaches the combustion chamber, and an upstream portion connected to an upstream end of the connecting portion. The connecting portion is provided at its downstream end with a valve seat with which an umbrella part of an intake valve is brought into contact. At least one recess extending in an extending direction of the intake port and included in the connecting portion and the upstream portion is provided at least at one of two portions, the two portions located on both sides in an extending direction of an output shaft, of a peripheral surface of the intake port.

A piston may have an annular body including a crown portion defining a longitudinal axis, a radial direction perpendicular to the longitudinal axis, a plane containing the longitudinal axis and the radial direction, and a contoured combustion bowl. In the plane containing the longitudinal axis and the radial direction, the crown portion includes a radially outer squish surface, and a swirl pocket having a reentrant surface that extends axially downwardly and radially outwardly from the squish surface defining a tangent that forms a reentrant angle with the squish surface that ranges from 53.0 degrees to 57.0 degrees.

A device and method for preventing and removing carbon deposit build-up on a piston/cylinder assembly of an engine, including a diesel engine, is disclosed. The device includes a cylinder having an inner sleeve for receiving a piston, a carbon scraping ring positioned on the cylinder sleeve, the carbon scraping ring including an inner surface, and an abradable coating applied to the inner surface of the carbon scraping ring providing a wearable surface between the piston and the cylinder sleeve. The abradable coating has a wearable surface, which conforms to the shape created by the movement of the piston and the cylinder sleeve and carbon scraping ring, creating a substantially zero clearance fit between the piston and the carbon scraping ring. The clearance may reduce oil consumption and improve sealing of the cylinder and piston, thereby reducing blow-by.

A device and method for preventing and removing carbon deposit build-up on a piston/cylinder assembly of an engine, including a diesel engine, is disclosed. The device includes a cylinder having an inner sleeve for receiving a piston, a carbon scraping ring positioned on the cylinder sleeve, the carbon scraping ring including an inner surface, and an abradable coating applied to the inner surface of the carbon scraping ring providing a wearable surface between the piston and the cylinder sleeve. The abradable coating has a wearable surface, which conforms to the shape created by the movement of the piston and the cylinder sleeve and carbon scraping ring, creating a substantially zero clearance fit between the piston and the carbon scraping ring. The clearance may reduce oil consumption and improve sealing of the cylinder and piston, thereby reducing blow-by.

An internal combustion engine has a uniblock that defines a blind cylinder bore that terminates within the uniblock. A piston is inserted into the cylinder bore from a bottom end of the cylinder bore. Parallel first and second vertical planes extend along first and second lateral sides of the cylinder bore. A cylinder zone being defined between the first and second vertical planes. A crosshead is coupled to the piston. A first crankshaft has a first crankshaft axis that extends parallel to the first vertical plane and that is positioned outside of the cylinder zone. A second crankshaft has a second crankshaft axis that extends parallel to the second vertical plane and that is positioned outside of the cylinder zone. The first crankshaft is coupled to the crosshead with a first connecting rod and the second crankshaft is coupled to the crosshead with a second connecting rod.