W8 engine

A W8 engine is an eight cylinder piston internal combustion engine in a W configuration, or two imaginary 15 degree V4 engine blocks, mounted juxtaposed at 72 degrees to one another and coupled to one crankshaft.

The W8 can be imagined as flat plane crank V8 engine made with VR4s instead of inline fours. Nearly-square external dimensions mean the large eight cylinder engine will fit in the space typically alloted for a V6 engine.

Usage
The Volkswagen Group W8 engine was installed longitudinally in the Volkswagen Passat (B5.5) from September 2001 to September 2004, but sales were minimal at only 10,000 units worldwide per year.

This petrol engine was to power the 'Passat W8' - supposedly as Volkswagen Passenger Cars' 'premium' positioned car - before the Volkswagen Phaeton came out. The 4.0 litre - 3,998 cubic centimetres (244.0 cu in) W8 engine produced 202 kilowatts (275 PS; 271 bhp) at 6,000 revolutions per minute (rpm) and 370 newton metres (273 ft·lbf) of torque at 2,750 rpm, yet was considered a fuel-efficient eight cylinder engine due to the design. It also had a two stage resonance induction system to boost cylinder filling across the engine speed range. It had two simplex roller chain-driven (relay method, using three chains) double overhead camshaft (2xDOHC - two overhead camshafts per cylinder bank - 'quad cam'), and twin balance shafts to smooth out residual vibrations inherent in the layout. One additional advantage was that the W8 shared some components and machining with narrow-angle VR5 and VR6 engines, leading to cost reduction in one of the most expensive engines Volkswagen Passenger Cars has ever produced.

The 2006 redesign of the Passat (B6), with its engine re-oriented transversely, it was no longer equipped with the W8, and the 'large' 3.6 litre VR6 engine has replaced its position at the top of the range. However, while the W8 had less horsepower than the 3.6 VR6 which replaced it, it still provides more torque, is more technically advanced, and is mounted in a better manner than current VR6 engines.