Originally posted by CSM:
This says the 2007 S8's engine was sourced from the Gallardo. Not sure exactly what that means, but assuming that the engine was a derivative of, though not exactly the same as, the Gallardo's engine.http://www.autoblog.com/2005/1...w-v10-from-gallardo/
The S8, in its current form, uses a super-super charged 4 liter V-8 seen here
The R8 uses the normally aspirated 5.2 Liter V-10 first developed for the Gallardo that can be seen here
once you click on the 5.2L engine.
The R8 also shares the same platform and technology* as the Gallardo whereas the S8 is just an A8 with some improvements for performance.
Audi shifts around its engines a lot, and especially as of recent as their turbo technology has really taken off. So one engine being in a car 5 or 6 years ago has very little chance of having much to do with what exists now. For example, neither of the currently available A6 engines nor the S6 engine were available for the -6 body 5 years ago, and only one of the currently available engines (the 2.0T) existed in any form in any Audi at all (and it had substantially less power back then).
*There may be differences in the non manual shifting option depending upon exact year and model.