Alexandre,
June 2000 HRM has a full tech analysis of the Vortec L6. We have reprint permission for the Inliners magazine, but it's 6 pages long and we haven't found the room yet.
On a tour of the Flint engine plant where these engines are made, I was told that 270 HP is a very mild state of tune for this engine. A version with variable intake cam timing is ready for production, should the market require it. Over 300 HP and 300 ft/lb normally aspirated. a 5-cylinder twin turbo version makes over 700 HP! But due to the tall height of the Vortec design, it will probably never be seen in a GM passenger car - it's for the truck platform only.
