W8 engine

A W8 engine is an eight-cylinder piston engine with four banks of two cylinders each, arranged in a W configuration.

In practice, the W8 engine is created from two narrow-angle (15 degree) VR4 engines mounted at an angle of 72 degrees from each other on a common crankshaft. Thus, the resulting four banks align to form a "W".

W8 engines are much less common than V8 engines, and the only W8 engine to reach production was manufactured by Volkswagen from 2001–2004 north America (but up to 05 and 06 for Euro/JPN)

Volkswagen W8 engine
The sole W8 engine to reach production was the Volkswagen 4-litre W8 engine, which was available in the Volkswagen Passat (B5.5) from September 2001 to September 2004. Production was minimal at only 11,000 units.

This engine had a displacement of 3,999 cc, had a peak power rating of 202 kW at 6,000 rpm and a peak torque rating of 370 Nm at 2,750 rpm. Power and torque outputs were lower than competitors V8 engines with similar capacity, however the W8 engine was praised for its smoothness.

Sales of the W8-engined Passat models were poor, and production was discontinued when the next generation of Passat switched from a longitudinal engine to a transverse engine layout, which made packaging of the wide W8 engine difficult. The W8 was effectively replaced by the Volkswagen 3.6-litre VR6 petrol engine.

4.0 WR8 32v 202kW
The 'W8' badged engine is an eight-cylinder W engine of four banks of two cylinders, formed by joining two 15° VR4 engines, placed on a single crankshaft, with each cylinder 'double-bank' now at a 72° vee-angle.
 * identification: parts code prefix: 07D, ID codes: BDN (09/01-09/04), BDP (05/02-09/04)
 * engine displacement & engine configuration: 3999 cc 72° WR8 engine; bore x stroke: 84.0 x, stroke ratio: 0.93:1 – undersquare/long-stroke, 499.9 cc per cylinder, compression ratio: 10.8:1
 * cylinder block & crankcase: cast aluminium alloy with two-part cast aluminium alloy oil sump; five main bearings; die-forged steel crankshaft with split crankpins; Lanchester principle balance shafts one above the other, counter-rotating at twice the crankshaft speed, symmetric to the middle of the crankshaft, upper one driven by a toothed belt
 * cylinder heads & valvetrain: cast aluminium alloy; four unequal-length valves per cylinder, 32 valves total, low-friction roller finger cam followers with automatic hydraulic valve clearance compensation, simplex roller chain-driven (relay method, using three chains) double overhead camshafts, continuous vane-adjustable variable valve timing for intake and exhaust camshafts with up to 52° variance inlet camshafts and 22° for exhaust camshafts
 * aspiration: hot-film air mass meter, single throttle body with electronically controlled Bosch 'E-Gas' 'drive by wire' throttle butterfly valve, four-part two-channel cast aluminium resonance intake manifold
 * fuel system, ignition system, engine management: two linked common rail fuel distributor rails, multi-point electronic sequential indirect fuel injection with eight intake manifold-sited fuel injectors; centrally positioned NGK longlife spark plugs, mapped direct ignition with eight individual direct-acting single spark coils; Bosch Motronic ME electronic engine control unit (ECU), cylinder-selective knock control via four knock sensors, permanent lambda control; 95 RON/ROZ(91 AKI) EuroSuperPlus (premium) unleaded recommended for maximum performance and fuel economy
 * exhaust system: vacuum-operated secondary air injection pump for direct injection into exhaust ports to assist cold start operation, one cast iron exhaust manifold per cylinder bank with integrated ceramic catalytic converter per cylinder bank, four heated oxygen sensors monitoring pre- and post catalyst exhaust gasses, EU4 compliant
 * dimensions: mass: 190 kg, length: 420 mm length, width: 710 mm, height: 683 mm
 * DIN-rated motive power & torque output: 202 kW at 6,000 rpm; 370 Nm at 2,750 rpm (11.6 bar MEP); max. engine speed: 6,400 rpm (19.2 m/s)
 * references:

Applications

 * Volkswagen Passat B5.5 W8 4motion

Awards

 * was voted 'best technical innovation', and awarded the "Golden Pegasus" by "Za ruljom" at the Moscow Motor Show