AW engine is a type ofpiston engine where three or fourcylinder banks share the samecrankshaft, resembling the letter "W" when viewed from the front.[1][2][3]
W engines with three banks of cylinders are also called "broad arrow" engines, due to their shape resembling the British governmentbroad arrow property mark.[1][4]
The most common W-type engine is the 4-bank type, with theVolkswagen Group experimenting with thePassat W8 and its 4.0 liter, 4-bank W8 engine and later implementing the concept with the group'sBentley division, creating a 6.0 literW12 in both naturally aspirated andturbocharged variants. Due to the pre-existingVR-type engine only needing one cylinder head despite having two banks of cylinders, a Volkswagen 4-bank W-type engine is structured more similarly to a conventional 2-bankV engine as opposed to a "true" W engine.
W engines are significantly less common than V engines. Compared with a V engine, a W engine is typically shorter but wider. In Volkswagen’s case, this allows for superior packaging in engine compartments intended for 6 and 8 cylinder engines, the Passat W8 being one such example.
One of the first W engines was theAnzani 3-cylinder, built in 1906, to be used in Anzani motorcycles. This W3 engine also powered the 1909Blériot XI, the first airplane to fly across the English Channel.[5]
TheFeuling W3 is a 2.5 L (153 cu in) motorcycle engine that was built by an aftermarket parts company in the United States in the early 2000s.[6] Like radial aircraft engines it has a masterconnecting rod and two slave rods connected to the pistons.[7]
TheRumpler Tropfenwagen had aSiemens and Halske-built[8] 2,580 cc (157 cu in)overhead valve W6 engine, with three banks of paired cylinders, all working on a common crankshaft.[8][9]
The sole W8 engine to reach production is theVolkswagen Group W8 engine automotive engine, which used a four-bank design and was produced from 2001-2004.[10]
W12 engines with three banks of four cylinders were used by several aircraft engines from 1917 until the 1930s. A three-bank W12 design was also used unsuccessfully by theLife F1 team in the1990 Formula One season, failing to qualify at every race.[11]
Although less commonly used in automobiles than V12 engines, a W12 petrol engine has been produced by theVolkswagen Group starting in 2001. This four-bank engine—based on twoVR6 engines with a common crankshaft—has been used in various cars sold under the Audi, Bentley and Volkswagen brands and has appeared in multiple variants, including a rare 6.3L normally aspirated version only available in the D4Audi A8 L. In 2018 the Volkswagen Group announced the W12 engine would be exclusive to vehicles produced by theirBentley division[12]
W16 engines are rarely produced, with the notable exception of theVolkswagen Group 8.0 WR16 engine that has been used since 2005. The W16 type of engine can also be found in theBugatti Veyron,Chiron,Divo and their related models.[13]
The W18 layout is rarely used, with the only production examples being several aircraft during the 1920s and 1930s, andCRM Motori SpA marine engines.
TheAllison V-3420, manufactured by theAllison Engine Company, is an example of a W24 engine.[citation needed]
TheChrysler A57 multibank, essentially five 250.6 cu in (4.1 L)Chrysler flathead engines driving one output shaft through a gear train, saw action duringWorld War II. Developed in 1941, it would be used inside variants of theM3 Lee andM4 Sherman tanks, all deployed on theWestern Front.[14] The A57 is the only example of a five-bank W configuration.[citation needed]
The W, or broad arrow engine, has three rows of cylinders of which the central row is vertical with the other two rows forming equal angles with the vertical.
W engine is similar to a V engine but with three banks of cylinders. The two V angles are usually equal.
W-engine Same as V-engine except with three banks of cylinders on the same crankshaft.