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Cylinder Head

 
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In an internal combustion engine
Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs in a combustion chamber inside and integral to the engine. In an internal combustion engine it is always the expansion of the high temperature and pressure gases that are produced by the combustion which apply force to the movable component of the engine, such as...
, the cylinder head sits above the cylinders
Cylinder (engine)

A cylinder is the central working part of a reciprocating engine, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically casting from aluminum or cast iron before precision features are machined into it....
 and consists of a platform containing part of the combustion chamber
Combustion chamber

A combustion chamber is the part of an engine in which fuel is burned....
 and the location of the valve
Poppet valve

A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem....
s and spark plug
Spark plug

A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed Particulate gasoline by means of an electric spark....
s. In a flathead engine
Flathead engine

A flathead engine or sidevalve engine is an internal combustion engine with poppet valve placed in the engine block beside the piston, instead of in the cylinder head, as in an overhead valve engine....
, the mechanical parts of the valve train are all contained within the block, and the head is essentially a flat plate of metal bolted to the top of the cylinder bank
Cylinder bank

Piston engines are typically arranged with their pistons in rows, moving inside individual cylinders. This allows the engine block to be built from a single piece of machined metal....
 with a head gasket
Head gasket

A head gasket is a gasket that sits between the engine block and cylinder head in an internal combustion engine. Its purpose is to seal the cylinders to ensure maximum compression ratio and avoid leakage of coolant or engine oil into the cylinders; as such, it is the most critical sealing application in any engine, and, as part of the comb...
 in between; this simplicity leads to ease of manufacture and repair, and accounts for the flathead engine's early success in production automobiles and continued success in small engines, such as lawnmowers.






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Cylinderhead
In an internal combustion engine
Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs in a combustion chamber inside and integral to the engine. In an internal combustion engine it is always the expansion of the high temperature and pressure gases that are produced by the combustion which apply force to the movable component of the engine, such as...
, the cylinder head sits above the cylinders
Cylinder (engine)

A cylinder is the central working part of a reciprocating engine, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically casting from aluminum or cast iron before precision features are machined into it....
 and consists of a platform containing part of the combustion chamber
Combustion chamber

A combustion chamber is the part of an engine in which fuel is burned....
 and the location of the valve
Poppet valve

A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem....
s and spark plug
Spark plug

A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed Particulate gasoline by means of an electric spark....
s. In a flathead engine
Flathead engine

A flathead engine or sidevalve engine is an internal combustion engine with poppet valve placed in the engine block beside the piston, instead of in the cylinder head, as in an overhead valve engine....
, the mechanical parts of the valve train are all contained within the block, and the head is essentially a flat plate of metal bolted to the top of the cylinder bank
Cylinder bank

Piston engines are typically arranged with their pistons in rows, moving inside individual cylinders. This allows the engine block to be built from a single piece of machined metal....
 with a head gasket
Head gasket

A head gasket is a gasket that sits between the engine block and cylinder head in an internal combustion engine. Its purpose is to seal the cylinders to ensure maximum compression ratio and avoid leakage of coolant or engine oil into the cylinders; as such, it is the most critical sealing application in any engine, and, as part of the comb...
 in between; this simplicity leads to ease of manufacture and repair, and accounts for the flathead engine's early success in production automobiles and continued success in small engines, such as lawnmowers. This design, however, requires the incoming air to flow
Air flow bench

An air flow bench is a device used for testing the internal aerodynamic qualities of an engine component and is related to the more familiar wind tunnel....
 through a convoluted path, which limits the ability of the engine to perform at higher rpm
Revolutions per minute

Revolutions per minute is a units of measurement of frequency: the number of Turn completed in one minute around a rotation around a fixed axis....
, leading to the adoption of the overhead valve
Overhead valve

An overhead valve engine, also called pushrod engine or I-head engine is a type of piston engine that places the camshaft in the cylinder block and uses pushrods or rods to actuate rocker arm above the cylinder head to actuate the poppet valve....
 head design.

In the overhead valve head, the top half of the cylinder head contains the camshaft
Camshaft

The camshaft is an apparatus often used in piston engines to operate poppet valves. It consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes or cams protruding from it, one for each valve....
 in an overhead cam engine, or another mechanism (such as rocker arm
Rocker arm

Generally referred to within the internal combustion engine of automotive, marine, motorcycle and reciprocating aviation engines, the rocker arm is a reciprocating lever that conveys radial movement from the cam lobe into linear movement at the poppet valve to open it....
s and pushrods) to transfer rotational mechanics from the crankshaft
Crankshaft

The crankshaft, sometimes casually abbreviated to crank , is the part of an engine which translates reciprocation linear piston motion into rotation....
 to linear mechanics to operate the valves (pushrod engines perform this conversion at the camshaft lower in the engine and use a rod to push a rocker arm that acts on the valve). Internally the cylinder head has passages called ports
Cylinder head porting

Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve the quality and quantity of the gas flow....
 for the fuel/air mixture to travel to the inlet valves from the intake manifold
Manifold (automotive engineering)

In automotive engineering, an intake manifold or inlet manifold is the part of an engine that supplies the fuel/air mixture to the cylinder s....
, for exhaust
Exhaust

Exhaust or exhaustion may refer to:...
 gases to travel from the exhaust valves to the exhaust manifold, and for antifreeze
Antifreeze

Antifreeze is a cryoprotectant used in internal combustion engines, and for many other heat transfer applications, such as HVAC chillers and solar water heaters....
 to cool the head and engine.

The number of cylinder heads in an engine is a function of the engine configuration
Engine configuration

Engine configuration is an engineering term for the layout of the major components of an internal combustion engine. These components include cylinder s, pistons, crankshaft and camshaft....
. A straight engine
Straight engine

Usually found in 4- and 6-cylinder configurations, the straight engine is an internal-combustion engine with all cylinders aligned in one row, with no or only minimal offset....
 has only one cylinder head. A V engine
V engine

A V engine is a common engine configuration for an internal combustion engine. The Cylinder_%28engine%29 and pistons are aligned, in two separate planes, so that they appear to be in a "V" when viewed along the axis of the crankshaft....
 usually has two cylinder heads, one at each end of the V, although Volkswagen
Volkswagen

Volkswagen Passenger Cars, also known as VW, is an automobile manufacturer based in Wolfsburg, Germany and is the original as well as the largest brand by sales volume within the Volkswagen Group....
, for instance, produces a V6 called the VR6, where the angle between the cylinder banks is so narrow that it utilizes a single head. A boxer engine
Flat engine

A flat engine is an internal combustion engine with pistons that are all relatively horizontal. A straight engine canted 90 degrees from straight up is a flat engine, as is one in which the cylinder s are arranged in two banks on either side of a single crankshaft....
 has two heads.

The cylinder head is key to the performance of the internal combustion engine, as the shape of the combustion chamber, inlet passages and ports (and to a lesser extent the exhaust) determines a major portion of the volumetric efficiency
Volumetric efficiency

Volumetric efficiency in internal combustion engine design refers to the efficiency with which the engine can move the charge into and out of the Cylinder ....
 and compression ratio
Compression ratio

The compression ratio of an internal-combustion engine or external combustion engine is a value that represents the ratio of the volume of its combustion chamber; from its largest capacity to its smallest capacity....
 of the engine.

Gallery


See also

  • Crossflow cylinder head
    Crossflow cylinder head

    A crossflow cylinder head is a cylinder head that features the intake manifold and exhaust manifold ports on opposite sides. The gases can be thought to flow across the head....
  • Engine tuning
    Engine tuning

    Engine tuning is the adjustment, modification or design of internal combustion engines to yield optimal performance, to increase an engine's power output, economy, or durability....


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