Does the Audi A8L W12 have a timing belt or chain?

Chain- http://www.audiworld.com/model/a8/05/05A8LW12.pdf

The service/maintenance schedule is $12 to download, so I can't say. But usually timing chains are good for life of engine ... 420 HP, wow

Does a W12 have 1 or 2 timing chains? A W12 is two v6 engines connected into a "W" configuration.

For a brief overview, all W12 Audi/VW Engines are Chain driven. Timing aswell. Its basically 2 VR6 Engines, which is a offset Inline 6. Like what FordNut said above, a normal VR6 is a dual-overhead cam design, thus a W12 would have 4 total camshafts, 2 for each bank, both with a tensioner to tighten or loosen timing for intake/exhaust and a main chain for linking the crank to both sprockets that join both the chains for the camshafts. The engine is actually smaller in physical size than a 4.2 BFM V8 in the A8 (both the belt motor and chain motors) Though when you need to do timing and chain pads its a engine out job, engines with a timing chain (Anything after 2005/2006) on all Audi longitude engines, are at the firewall.