W12 engine

A W12 engine is a twelve cylinder piston engine in a W configuration. W12 engines are manufactured in two distinct configurations. One configuration uses four banks of three cylinders (two narrow-angle V6 engine blocks), coupled to a common crankshaft "(e.g. VW W12)". The other uses three banks of four cylinders coupled to a common crankshaft "(e.g. Napier Lion)".

Napier Lion

One of the most famous W12 engines was the Napier Lion (Broad arrow) which was produced by Napier at Acton, North London, from 1917 to the late 1930s. This mostly alloy engine had a capacity of 24 litres and produced from 450 hp to 900 hp. It was used in many racing cars by John Cobb and Malcolm Campbell, racing aircraft such as the Supermarine S.5 Schneider Cup winner, and speed boats such as Hubert Scott-Paine's Miss Britain III. This configuration had 3 separate 4 cylinder banks each at 60 degrees offset from one another, as opposed to the "double V" layout used by VW-Audi AG.

Volkswagen W12

At the 2001 Tokyo Motor Show, Volkswagen showcased the W12 Coupe, a mid-engined, rear wheel drive supercar powered by a 6 L W12 engine producing 600 hp. A week before, the W12 Coupe broke the world 24 hour endurance record. A total distance of 7085.7 kilometres (4402.8 miles) was covered at an average speed of 295.24 km/h (185.45 mph), breaking the old record by 12 km/h (7.5 mph). Production of the W12 Coupe was considered but is currently cancelled.

Volkswagen Group currently produces W12s based on two of its narrow-angle VR6 engines. The narrow angle of each set of cylinders allows just two camshafts to drive each pair of banks, so just four are needed in total. Note that this design differs from the W18 engine that Volkswagen produced for its Bugatti concept cars of 1998 and 1999. Due to this distinction, the VW Group's W12 engine is sometimes described as a "WR12".

The VW W12 is used in some high-end luxury models:
* Audi A8
* Bentley Continental GT
* Bentley Continental Flying Spur
* Spyker C12 LaTurbie
* Spyker C12 Zagato
* Spyker D12 Peking-to-Paris
* Volkswagen Phaeton
* Volkswagen Touareg W12
* Volkswagen Golf W12

MGN

In the late 1980s two W12 engines were designed and built for use in Formula 1. In France Guy Negre produced the MGN which had three banks of four cylinders offset so that each crankpin accommodated three connecting rods side-by-side. The MGN also had a novel system of cylindrical rotary valves located at the top of the combustion chambers making the engine notably compact. The engine was tested in an AGS Formula 1 car and in a Norma sports car but never raced.

Life

The other W12 Formula 1 engine was built in Italy by Life Racing Engines. The chief engineer for this project was Franco Rocchi who had already designed and built an experimental 498cc W3 engine when he was at Ferrari in 1967 as an investigation into the viability of a W18 Formula 1 engine. Rocchi's W3 engine used a central master connecting rod with a slave rod locating onto each side of the master rod rather than directly onto the crank pin. This meant that there was no offset between the cylinders and the crankpin did not have to be unusually long. A similar arrangement was employed for the Life W12 engine. Life Racing Engines failed to attract the interest of an existing team so they acquired a Formula 1 chassis which had been built for another team and tried to enter Formula 1 on their own account in 1990. The engine proved to be unreliable and lacking in power. The car never qualified for a race.

External links

* [http://www.autozine.org/technical_school/engine/tech_engine_packaging.htm#W12 Volkswagen's VR6 and W-engines]