Cylinder bank
Internal combustion piston engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

s (those with more than one cylinder) are usually arranged so that the cylinders are in lines parallel to the crankshaft
The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...

. Where they are in a single line, this is referred to as an inline or straight engine
Straight engine
Usually found in four- and six-cylinder configurations, the straight engine, or inline engine is an internal-combustion engine with all cylinders aligned in one row, with no offset...


Where engines have a large number of cylinders, the cylinders are commonly arranged in two lines, placed at an angle to each other as a vee engine
V engine
A V engine, or Vee engine is a common configuration for an internal combustion engine. The cylinders and pistons are aligned, in two separate planes or 'banks', so that they appear to be in a "V" when viewed along the axis of the crankshaft...

. Each line is referred to as a cylinder bank. The angle between cylinder banks is described as the bank angle.

Engines with six cylinder
Six cylinder engine
Six cylinder engine may refer to*V6 engine, a V engine with six cylinders.*Straight-6, an engine with six cylinders aligned in a single row.*Flat-six engine with two banks of three cylinders 180° apart...

s are equally common as either straight or vee engine. With more cylinders than this, the vee configuration is more common. Fewer cylinders are more usually arranged as an inline engine. There are exceptions to this: straight-8 engines were found on some pre-war luxury cars with the bonnet length to house them. A few V4 engine
V4 engine
A V4 engine is a V form engine with four cylinders and three main bearings.-Automobile use:Lancia produced several narrow-angle V4 engines from the 1920s through 1960s for cars like the Lambda, Augusta, Artena, Aprilia, Ardea, Appia, and Fulvia....

s have also been produced, usually where an extra-compact engine was required, including some outboard motor
Outboard motor
An outboard motor is a propulsion system for boats, consisting of a self-contained unit that includes engine, gearbox and propeller or jet drive, designed to be affixed to the outside of the transom and are the most common motorized method of propelling small watercraft...

s with a vertical crankshaft. Although twin cylinder engines are now rare for cars, they are still commonly used for motorcycles and the vee-twin and inline twin are both widely used.

An obvious advantage to a multi-bank engine is that it can be shorter in length. This allows a torsionally stiffer construction for both the crankshaft and crankcase
In an internal combustion engine of the reciprocating type, the crankcase is the housing for the crankshaft. The enclosure forms the largest cavity in the engine and is located below the cylinder, which in a multicylinder engine are usually integrated into one or several cylinder blocks...

. The most important advantage though is less obvious: a multi-plane engine can be arranged to have better balance
Engine balance
Engine balance is the design, construction and tuning of an engine to run smoothly. Improving engine balance reduces vibration and other stresses and can improve the overall performance, efficiency, cost of ownership and reliability of the engine, as well as reducing the stress on other machinery...

 and less vibration. This depends on the layout of the crankshaft more than the cylinder banks alone: the planes on which the pistons are arranged, thus their timing and vibration, depend on both the cylinder bank and the crankshaft angles.

Unusual arrangements

The W
W engine
A W engine is a type of reciprocating engine arranged with its cylinders in a configuration in which the cylinder banks resemble the letter W, in the same way those of a V engine resemble the letter V....

 or broad arrow
Broad arrow
A broad arrow or pheon is a type of arrow with a typically flat barbed head. It is a symbol used traditionally in heraldry, most notably in England, and later the United Kingdom to mark government property.-Use in heraldry:...

 arrangement uses three cylinder banks, usually a W-12 with three banks of four cylinders.

Narrow-angle vee engines, such as the Lancia V4
Lancia V4 engine
Lancia pioneered the V engine design, producing the first V6 as well as the first V4s. Several different V4 families were produced from the 1920s through 1960s.-Lambda:...

 and the Volkswagen VR6
VR6 engine
The VR6 engine is an internal combustion engine configuration, consisting of six cylinders. It was developed by the Volkswagen Group in the late 1980s, and evolutions of the original variant are still produced by them....

, have such a narrow bank angle that their cylinders are combined into a single cylinder block
Cylinder block
A cylinder block is an integrated structure comprising the cylinder of a reciprocating engine and often some or all of their associated surrounding structures...

. These are still described as vee engines, although they may be described as having either two (as for other engines) or (more commonly in these cases) one cylinder bank.

Radial engines

In a radial engine
Radial engine
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders point outward from a central crankshaft like the spokes on a wheel...

, cylinders are arranged radially in a circle. Simple radials use one row (i.e. one circle) of cylinders. Larger radials use two rows, or even four. Most radials are air-cooled with separate cylinders and so there are no banks as such. Most radials also have odd numbers of cylinders in each row and stagger these between successive rows, for better cooling.

A few rare radial engines, such as the Armstrong Siddeley Deerhound
Armstrong Siddeley Deerhound
|-See also:-Bibliography:*Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9...

 and the Zvezda M503 (illustrated) have arranged their multiple rows so as to align their cylinders into banks.
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