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      05-24-2011, 08:07 PM   #64
JoosyJoos
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Quote:
Originally Posted by mkoesel View Post
But wait a minute.

Speaking purely from an economies of scale perspective - BMW sells many, many times as many I6 engines as they do V8 engines. The I6 is used in every single model BMW sells currently, and is produced in greater numbers than the V8 sibling in every model where both are available, except maybe the F0x (and even there, I would still guess the I6 sells more). So, with that in mind, it would actually make much more sense for the M engine to share the already engineered, already tested, already completely done I6 short-block than it would to borrow parts from the V8. Sure, in either case, you can use some existing parts. But think about it - no matter how you slice it, if you go creating a new V6 engine, you are going to need a ton of new V6-specific parts such as the crank-shaft, cam shafts, block, etc.

If BMW wants to drive cost down for the V8 and create economies of scale for the part content used in that engine, then the better way to handle that would be to share pistons, rods, valves, injection system, other valvetrain components, etc. with the I6, and for that matter with the I4 as well (some rumors suggest that they intend to do exactly this starting with the next generation of engines). I can't fathom why you would instead pick a low volume model like an M3 to build a parts-sharing business case with, especially when, as I say above, you end up wiping out a portion of the money you just saved by now requiring a bunch of V6-specific parts for this M engine.

I'm not trying to be difficult, but honestly I just don't follow your line of reasoning at all. To me, assuming that either a V6 or an I6 can both equally be designed and engineered to meet the performance, reliability, service life, etc, requirements, there is no scenario where it makes sense monetarily to up and switch to a V6. It is primarily for this very reason that I have been extremely skeptical of the V6 from the very outset when these discussions started up two years ago. And I've yet to hear anyone come up with a truly convincing argument that justifies why BMW has such a dire need for a V6 now.
Good points. I think the need for the V6 would be because the I6 can't be bored out enough to create the power the way they want. The N55 and N54 blocks are both different but as far as I'm aware they can't be bored out safely. So then you're looking at a whole new short block and the development costs associated with that. Then there's the fact that you're going to have an even longer (marginally) engine.
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