W engine
A W engine is a type of reciprocating engine
Reciprocating engine
A reciprocating engine, also often known as a piston engine, is a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This article describes the common features of all types...

 arranged with its cylinders in a configuration
Engine configuration
Engine configuration is an engineering term for the layout of the major components of a reciprocating piston internal combustion engine. These components are the cylinders and crankshafts in particular but also, sometimes, the camshaft....

 in which the cylinder bank
Cylinder bank
Internal combustion piston engines are usually arranged so that the cylinders are in lines parallel to the crankshaft. Where they are in a single line, this is referred to as an inline or straight engine....

s resemble the letter W, in the same way those of a V 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...

 resemble the letter V.

Three different configurations have been called W engines:
  • Three banks of cylinders
    Cylinder (engine)
    A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...

     sharing a common crankshaft
    The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...

    , a configuration also known as 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:...

    configuration due to its shape resembling the British government broad arrow property mark.
  • Four banks of cylinders sharing a common crankshaft
  • Two banks of cylinders with two crankshafts.

The original "three-bank" design

The classical W engine uses three banks of cylinders, all connected to one crankshaft.

One of the first W engines was a three-cylinder (W3), built by Anzani
Anzani was an engine manufacturer founded by the Italian Alessandro Anzani , which produced proprietary engines for aircraft, cars, boats, and motorcycles in factories in Britain, France and Italy.-Overview:...

 in 1906, to be used in its motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...

s. It is this W3 engine which also powered the Blériot XI
Blériot XI
The Blériot XI is the aircraft in which, on 25 July 1909, Louis Blériot made the first flight across the English Channel made in a heavier-than-air aircraft . This achievement is one of the most famous accomplishments of the early years of aviation, and not only won Blériot a lasting place in...

, the aircraft used by Louis Blériot
Louis Blériot
Louis Charles Joseph Blériot was a French aviator, inventor and engineer. In 1909 he completed the first flight across a large body of water in a heavier-than-air craft, when he crossed the English Channel. For this achievement, he received a prize of £1,000...

 when, on 25 July 1909, he made the first flight across the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

. Shortly afterward the W3 configuration was changed to a 120°-angle, three-cylinder 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...

 configuration as the original W3 engine's replacement.

The 1917 Napier Lion
Napier Lion
The Napier Lion was a 12-cylinder broad arrow configuration aircraft engine built by Napier & Son starting in 1917, and ending in the 1930s. A number of advanced features made it the most powerful engine of its day, and kept it in production long after contemporary designs had stopped production...

 aircraft engine was an early W12 engine
W12 engine
A W12 engine is a twelve cylinder piston internal combustion engine in a W configuration. W12 engines are manufactured in two distinct configurations. One configuration uses four rows of three cylinders merged into two 'cylinder banks' , coupled to a common crankshaft - as in Volkswagen Group W12...

. Lorraine built the 12Ed and 18Ka aero-engines of 450 hp and 650 hp in the early 1920s, while Isotta-Fraschini
Isotta Fraschini represents two Italian manufacturing companies which produce, respectively, marine engines and luxury goods. In the early 20th century it was famous worldwide as a luxury car manufacturer.-History:...

 built the 18-cylinder Asso 750 and Asso 1000 of 820 hp and 1100 hp in the late 1920s.

A three-bank W12 design was also pursued by Audi
Audi AG is a German automobile manufacturer, from supermini to crossover SUVs in various body styles and price ranges that are marketed under the Audi brand , positioned as the premium brand within the Volkswagen Group....

, which later abandoned the project. Volkswagen Group
Volkswagen Group
Volkswagen Group is a German multinational automobile manufacturing group. , Volkswagen was ranked as the world’s third largest motor vehicle manufacturer and Europe's largest....

 built an experimental W18 engine
W18 engine
A W18 engine is an eighteen cylinder piston engine which usually has a single crankshaft with three banks of six cylinders arranged in an inverted broad arrow configuration. Recent W18 engines powered the Bugatti EB 118, Bugatti EB 218 and Bugatti 18/3 Chiron concept cars in the late 1990s. This...

 for Bugatti
Automobiles E. Bugatti was a French car manufacturer founded in 1909 in Molsheim, Alsace, as a manufacturer of high-performance automobiles by Italian-born Ettore Bugatti....

's EB 118 and EB 218 concept cars, but the design was determined to be impractical because of the irregular firing order
Firing order
The firing order is the sequence of power delivery of each cylinder in a multi-cylinder reciprocating engine.This is achieved by sparking of the spark plugs in a gasoline engine in the correct order, or by the sequence of fuel injection in a Diesel engine...

 required by the three rows of six cylinders.

The Feuling W

Similar to the W3 built by Anzani in 1906, the Feuling W3 is a 180 hp, three-cylinder air-cooled engine
Air-cooled engine
Air-cooled engines rely on the circulation of air directly over hot parts of the engine to cool them.-Introduction:Most modern internal combustion engines are cooled by a closed circuit carrying liquid coolant through channels in the engine block and cylinder head, where the coolant absorbs heat,...

 for motorcycle cruisers. Like radial aircraft engines it has a master connecting rod
Connecting rod
In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion....

 and two slave rods connected to the three 101.6 millimetres (4 in) pistons. Motorcycle Cruiser Magazine reviewed Feulings's "Warlock" powered motorcycle in the October edition of 2000. Cory Ness built his chopper using a Feuling W3 engine during a Biker Build Off episode.

The modern "four-bank" design

Volkswagen Group created the first successful automotive W engine, with the introduction of its W8
W8 engine
A W8 engine is an eight-cylinder piston internal combustion engine in a W configuration.The W8 can be imagined as flat plane crank V8 engine combining two narrow-angle V4 engine blocks, mounted juxtaposed at 72 degrees to each other and coupled to one crankshaft...

 (as a testbed for the W12). The W12 combines two narrow-angle VR6 engine
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....

 cylinder heads around a single crankshaft for a total of four banks of cylinders. For this reason, the four-bank configuration is sometimes, and more accurately, referred to as a "VV" ("vee-vee" or "double-vee") or "VR", to distinguish it from the traditional three-bank "W" design (the earlier W8 combined two VR4 engines.)

The W8 was used in the B5.5 Volkswagen Passat
Volkswagen Passat (B5)
A new version of the Volkswagen Passat, based on the Volkswagen Group B5 platform, was launched in 1996 in Europe, and 1997 in North America. Its PL45 platform was shared with the first-generation "Typ 8D" Audi A4, which was unveiled 2 years earlier, and saw a return to the Passat sharing its...

 and the W12 is used in the Volkswagen Phaeton
Volkswagen Phaeton
The Volkswagen Phaeton is a full-size luxury sedan/saloon manufactured by German automaker Volkswagen, and is described by Volkswagen as their "premium class" vehicle...

, the Volkswagen Touareg
Volkswagen Touareg
The Volkswagen Touareg is a mid-size crossover SUV produced by German automaker Volkswagen since 2002. The vehicle was named after the Tuareg people, a Berber-speaking group in North Africa...

, the Audi A8
Audi A8
The Audi A8 is a four-door, full-size, luxury sedan car manufactured and marketed by the German automaker Audi since 1994. Succeeding the Audi V8, the A8 has been offered with front wheel drive or permanent four-wheel drive, with multitronic or tiptronic automatic transmissions — and in short- and...

, and the Bentley Continental GT
Bentley Continental GT
-Flying Spur:The four door Continental Flying Spur saloon was first displayed at the 2005 Geneva Motor Show. The Flying Spur utilizes most of the technical underpinnings of the Bentley Continental GT, and was introduced to European and North American markets in the summer of 2005...

 — though in the latter application, the engine has been highly modified by Bentley
Bentley Motors Limited is a British manufacturer of automobiles founded on 18 January 1919 by Walter Owen Bentley known as W.O. Bentley or just "W O". Bentley had been previously known for his range of rotary aero-engines in World War I, the most famous being the Bentley BR1 as used in later...

, and fitted with twin turbocharger
A turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...

s. As a result, it produces considerably more power
Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...

 than the original version. The narrow (15°) angle between bank pairs makes this resemble a V12 engine
V12 engine
A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft....

, in that it has just two cylinder heads and two sets of camshaft
A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part.-History:An early cam was built into Hellenistic water-driven automata from the 3rd century BC. The camshaft was later described in Iraq by Al-Jazari in 1206. He employed it as part of his automata,...

s. The W12 engine has bore-stroke of 84 millimetres (3.31 in) and 90.2 millimetres (3.55 in).

Volkswagen Group went on to produce a W16 engine
W16 engine
A W16 engine is a sixteen cylinder piston internal combustion engine in a four-bank W configuration. All W16 engines consist of two 'offset double-row' banks of eight cylinders, coupled to a single crankshaft....

 prototype which produced 465 kW for the Bentley Hunaudières
Bentley Hunaudières
The Bentley Hunaudières is a concept car built by Bentley for the 1999 Geneva Salon International de l'Auto. It is powered by a Volkswagen 8.0-litre, naturally aspirated, W16 engine that generates of power at 6,000 revolutions per minute and of torque at 4,000 revolutions per minute in...

 concept car. A quad-turbocharged version of this engine went into production in 2005 powering the 736 kW Bugatti Veyron EB16.4
Bugatti Veyron
The Bugatti Veyron EB 16.4 is a mid-engined grand touring car. The Super Sport version is the fastest road-legal production car in the world, with a top speed of . The original version has a top speed of...

The major advantage of these engines is packaging; that is, they contain high numbers of cylinders but are relatively compact in their external dimensions.

The W-engine in the Bugatti Veyron

In 2006, the Volkswagen Group-owned Bugatti produced the Bugatti Veyron EB16.4
Bugatti Veyron
The Bugatti Veyron EB 16.4 is a mid-engined grand touring car. The Super Sport version is the fastest road-legal production car in the world, with a top speed of . The original version has a top speed of...

; with an 8.0 litre W16 engine. This had four turbochargers, and it produces DIN
DIN or Din or din can have several meanings:* A din is a loud noise.* Dīn, an Arabic term meaning "religion" or "way of life".* Din is one of the ten aspects of the Ein Sof in Kabbalah ....

 rated motive
Motive power
In thermodynamics, motive power is an agency, as water or steam, used to impart motion. Generally, motive power is defined as a natural agent, as water, steam, wind, electricity, etc., used to impart motion to machinery; a motor; a mover. The term may also define something, as a locomotive or a...

Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...

 output of 736 kW at 6,000 revolutions per minute
Revolutions per minute
Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...

 (rpm). It uses four valves
In automotive engineering a multi-valve or multivalve engine is one where each cylinder has more than two valves. A multi-valve engine has better breathing and can operate at higher revolutions per minute than a two-valve engine, delivering more power.- Multi-valve rationale :A multi-valve design...

 per cylinder, 64 valves total, with four overhead camshaft
Overhead camshaft
Overhead cam valvetrain configurations place the engine camshaft within the cylinder heads, above the combustion chambers, and drive the valves or lifters in a more direct manner compared to overhead valves and pushrods...

s arranged in a 2x double overhead camshaft (2xDOHC - two overhead camshafts per cylinder bank - sometimes referred to as a 'quad cam') layout, and a bore-stroke ratio 1:1 (both bore and stroke are 86 millimetres (3.39 in)).

The motorcycle "two-bank" design

A very rare type of W engine is found in motorcycles of the MotoGP class. These are two-stroke, 500 cc V engines with two banks of two cylinders and two separate crankshafts, one per bank of cylinders, thus constituting a sort of "W" form. The angle between the banks varies from 60 to 75 degrees.

There are two major advantages of this engine over the more traditional inline-four engine or 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....

. The first is the width of the engine: a V4 engine will be narrower than an inline-four engine with the same displacement
Engine displacement
Engine displacement is the volume swept by all the pistons inside the cylinders of an internal combustion engine in a single movement from top dead centre to bottom dead centre . It is commonly specified in cubic centimeters , litres , or cubic inches...

, but a W4 with its two crankshafts will be even smaller. The second advantage is that the W4 lacks the need for a balance shaft
Balance shaft
In piston engine engineering, a balance shaft is an eccentric weighted shaft which offsets vibrations in engine designs that are not inherently balanced...

; it will run smoothly if the two crankshafts rotate in opposite directions. This is a weight advantage over the V4 engine, which will need a balance shaft.

Examples of this type of W4 engine drive the Yamaha YZR500
Yamaha YZR500
The YZR500 was the Yamaha Motor Corporation’s entry for 500cc Grand Prix motorcycle racing between the years of 1973 and 2002.- Successes :...

 and the Cagiva
Cagiva is an Italian motorcycle manufacturer. It was founded in 1950 by Giovanni Castiglioni in Varese, originally producing small metal components. It went into the motorcycle industry in 1978. The name is a portmanteau derived from the founder and the founding location, i.e. CAstiglioni GIovanni...

 GP500 motorcycles.

This type of engine should not be confused with the U engine
U engine
A U engine is a piston engine made up of two separate straight engines joined by gears or chains. It is similar to the H engine which couples two flat engines...

, which also has two banks of cylinders and two crankshafts, but which is made by combining two similar 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...

s. The U engine lacks the advantages the "W" form of the engine has in terms of width and weight.

External links

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