VR6 engine


VR6 engines are V6 piston engines with a narrow angle between the cylinder banks and a single cylinder head covering both banks of cylinders.
Volkswagen Group introduced the first VR6 engine in 1991 and VR6 engines currently remain in production. From 1997-2006, Volkswagen also produced a five-cylinder VR5 engine based on the VR6.

Description

The name VR6 comes from the German initials for a V engine and a straight engine, therefore the VR engine is described as a "Vee-Inline engine".
VR6 engines shares a common cylinder head for the two banks of cylinders. Only two camshafts are needed for the engine, regardless of whether the engine has two or four valves per cylinder. This simplifies engine construction and reduces costs.
Since the cylinders are not located on the centreline of the combined cylinder head, the lengths of the intake and exhaust ports are different for each bank. Without compensation, these varying port lengths would result in the two banks of cylinders producing different amounts of power at a particular engine RPM. The difference in port lengths are compensated for with the length of the runners in the intake manifold, the camshaft overlap and lift profile, or a combination thereof.

Volkswagen engines

The Volkswagen VR6 engine was designed for transverse engine installations in front-wheel drive vehicles. The narrow angle of 15° between the two cylinder banks reduced the width of the engine, compared to a traditional V6 engine. Therefore the VR6 engine is easier to fit within an engine bay that was originally designed for a four-cylinder engine.

12-valve versions

Early VR6 engines had two valves per cylinder and used one camshaft for the intake and exhaust valves of each cylinder bank.
The first Volkswagen VR6 engine uses the AAA version. It had a bore of and a stroke of, for a total displacement of. In 1994, a ABV version was introduced in some European countries, with an increased bore of.
The V angle between the cylinder banks is 15°, and the compression ratio is 10:1. The crankshaft runs in seven main bearings and the journals are offset 22° to one another, in order to accommodate the offset cylinder placement. This also allows the use of a 120° firing interval between cylinders. The firing order is: 1, 5, 3, 6, 2, 4. The centerline of the cylinders are offset from the centerline of the crankshaft by.
The valve sizes are for the intake and for the exhaust. Since the two 'rows' of pistons and cylinders share a single cylinder head and head gasket, the piston crown is tilted. The engine management system is Bosch Motronic.

24-valve versions

A version with four valves per cylinder was introduced in 1999. The 24-valve versions use one camshaft for the intake valves of both banks and the other camshaft for the exhaust valves of each bank. This operating principle is more akin to a double overhead camshaft design, with one camshaft for intake valves, and one for exhaust valves.

History

The 1922-1976 Lancia V4 engine was the first narrow angle V engine to be used in a motor vehicle.
The first versions of the VR6 engine were introduced in the 1991 Volkswagen Passat B3 sedan and Volkswagen Corrado coupe. A AAA version producing was used in most Passat models and in the North American version of the Corrado. A ABV version producing was used in the Passat Syncro model and the European version of the Corrado. Both versions used 2 valves per cylinder. Usage of the VR6 engine spread to the Volkswagen Golf Mk3 2.8 VR6 and Volkswagen Vento/Jetta 2.8 VR6 models in 1992. The 2.8 litre version was also used in the 1996-2003 Mercedes-Benz Vito commercial vans, where it was designated as 'M104.900'.
In 1997, the VR5 engine was introduced, based on the VR6 engine.
An AQP/AUE version with 4 valves per cylinder was introduced in 2000. This engine produced, and mostly replaced the 2 valve engines, except for in North America where an updated version of the 2 valve engine was used in the Golf and Jetta from 2000-2002.
A EA390 version of the 4 valve engine was introduced in the 2001 Volkswagen New Beetle RSi model. This 3.2 litre engine was also used in the 2002-2004 Volkswagen Golf Mk4 R32 model and the 2003-2010 Audi TT 3.2 VR6 quattro models. Peak power output was in the New Beetle and Golf, and in the Audi TT.
The engine size was again increased in 2005, when a version with gasoline direct injection was introduced in the Volkswagen Passat. This BLV version uses a narrower 10.6 degree angle between the cylinder banks and produces. A AXZ version producing was introduced in 2006. In 2008, an uprated BWS version of the 3.6 litre engine producing was introduced in the Volkswagen Passat R36 model.
The base model Porsche Cayenne used 3.2-liter VR6 engine from 2003-2006 and then a 3.6-litre VR6 engine from 2008-2010. Then the next generation Porsche Cayenne also used a 3.6-litre VR6 engine from 2010-2018.
Volkswagen is currently phasing out VR engines in favour of downsized turbocharged engines, however the VR6 currently remains in production for the Volkswagen Passat sedan models sold in China and the Volkswagen Atlas SUV.

Applications

Volkswagen Group automobiles:
Other manufacturers:
Volkswagen Group has produced several 'W engines' based on combining two VR engines on a common crankshaft. The first W engine to reach production was the W12 engine which has been produced since 2001. The W12 engine is constructed from two VR6 engines mated together at an angle of 72 degrees. Although Volkswagen has not produced a VR4 engine, nonetheless it briefly produced a W8 engine from 2001-2004.
The largest Volkswagen W engine is the W16 engine introduced on the Bugatti Veyron in 2005. This engine uses an angle of 90 degrees between the two VR8 engines, and has four turbochargers.

Other manufacturers

Motorcycle manufacturer Horex has produced VR6 engines since 2012.