Here's some interesting articles on the Cayenne V8 engine:

http://www.autofieldguide.com/articles/110307.html

http://www.rheinmetall.com/index.php?lang=3&fid=1122

http://www.automotive.dupont.com/en/newsEvents/article20030723.html

I saw a longer, more detailed, article somewhere else; but I can't remember where.