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      10-07-2016, 09:22 AM   #75
mkoesel
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Quote:
Originally Posted by kyleb350 View Post
It looks like the competition mentioned all have between 550-600 HP. Why not just use the S63 to make this instead of a new 4.0L unit, unless there is going to be some new lightweight tech in it?
You are on the right track with the "lightweight" comment.

BMW's current N63/S63 V8 is based on the same architecture as their original M60 whose design dates back to the 1980s. It was conceived with a generous 98mm bore center and thus the ability to accommodate larger displacements over time. Indeed they have gone as high as 4.9L in the E39 M5 and the Z8. However, in today's world where everything is turbocharged, larger displacement is not necessary.

BMW's main rivals - Mercedes and Audi - have more compact designs. I believe Mercedes has a 90mm bore center while Audi's is 91mm. This not only makes for a slightly lighter engine (assuming everything else equal), but also allows for a smaller package by a few cm in length. This may seem like a minor point but packaging constraints are crucial - a few cm more and everything around must be larger in turn, which leads to weight gain in other components and areas of the vehicle.

So, although there is no hard info yet, the assumption here is that BMW's new V8 will be more compact. I suspect a 91mm bore center so that it can share common parts with the B* engine family, but that's just my speculation.
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