Editing VR6 engine (section)

=== 12-valve versions ===
Early VR6 engines had two valves per cylinder (for a total of twelve valves) and used one camshaft for the intake and exhaust valves of each cylinder bank (without the use of rockers).

The first Volkswagen VR6 engine uses the [[List of discontinued Volkswagen Group petrol engines#2.8 VR6 103-130kW|AAA version]]. It had a bore of {{convert|81.0|mm|in|2|abbr=on}} and a stroke of {{convert|90.3|mm|in|2}}, for a total [[Engine displacement|displacement]] of {{convert|2.8|L|cuin|0|abbr=on}}. In 1994, a {{convert|2.9|L|cuin|0|abbr=on}} [[List of discontinued Volkswagen Group petrol engines#2.9 VR6 140kW|ABV version]] was introduced in some European countries, with an increased bore of {{convert|82.0|mm|in|2|abbr=on}}.

The V angle between the cylinder banks is 15°, and the [[compression ratio]] is 10:1.<ref name=clemens>{{cite book|last1=Clemens|first1=Kevin|title=VW GTI, Golf, Jetta, MK III & IV|date=15 October 2006|publisher=Motorbooks International|location=St. Paul, MN|isbn=0-7603-2595-2|page=22}}</ref> The [[crankshaft]] runs in seven main bearings and the journals are offset 22° to one another, in order to accommodate the offset cylinder placement.<ref name=perf>{{cite book|last1=Raven|first1=Gregory|last2=Erickson|first2=Chad|title=Water-Cooled VW Performance Handbook: 3rd Edition|date=18 May 2011|publisher=MBI Publishing|isbn=978-1610601993|page=41}}</ref> This also allows the use of a 120° firing interval between cylinders.<ref>{{cite news|last1=Barber|first1=Thomas|title=Horex VR6 motorcycle|url=http://www.motorcycledaily.com/2012/03/the-new-horex-motorcycle-with-vr6-engine-a-technical-analysis/|access-date=23 June 2014|work=Motorcycle Daily}}</ref> The [[firing order]] is: 1, 5, 3, 6, 2, 4.<ref>{{cite book|last1=Schenck|first1=M|title=Automotive Design Engineering|date=1991|publisher=Century Press}}</ref> The centerlines of the cylinders are offset from the centerline of the crankshaft by {{convert|12.5|mm|in|2|abbr=on}}.

The valve sizes are {{convert|39.0|mm|2|abbr=on}} for the intake and {{convert|34.3|mm|2|abbr=on}} for the exhaust. Since the two rows of pistons and cylinders share a single cylinder head and head gasket, the piston crown (or top surface) is tilted. The engine management system is [[Motronic|Bosch Motronic]].