Originally Posted by fluidkaos
If it does end up with a 3 turbo setup, it will most likely be a compound setup with 2 small turbos/3 cylinders for the low end (like the N54) and the exhaust from both of those drives a larger turbo for the high end. The charge air would feed from the filter to the big turbo then split to the smaller turbos to get boosted once more before running through the intercooler. A compound turbo setup would be a perfect fit for an M car, even though it would be a further diversion from heritage. You get the throttle response of tiny turbos, and all the grunt of a big turbo, with none of the down sides of either.
The rumor of the 3.3ltr.V6TTT quotes ... 1 turbo on each side and one atop of the engine ... seems to be an nice small package!
I think weight distribution, better balance, compact packaging are the most logical reasons for an change from an I6 to an V6 ... and more logical if the M-GmbH will make use of the carbon-compound-parts developed for the i-Range cars ... if they would make the cars overall lighter in bigger numbers the quoted 3 Points are more and more important ... and at one point it make simply no more sence to use the "long(er)" I6 because it could bring the handling of the car on an worse direction.
This could be the logical background of an decission to change the engine layout!