Quote:
Originally Posted by Edubya
Hey all,
So, what motor differences exist between the B58 in the G05 X40i and the X3 M40i? What components of the X3 M40i engine are different, hardened etc. vs the motor in the X5 40i. As you are aware, the X3 M40i I6 motor has, what, 50 extra HP vs the larger and heavier X5 (which makes no sense to me), so, when we start adding boost to the X5 40i variant of the motor are we at risk because we have less capable components in the motor (or fuel pumps / injectors).
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TLDR; No, there's no significant risk because there are no significant differences.
The G05 X40i has the B58B30M1 mill, and the G01 X40i has the B58B30O1 unit. The "M1" is the "medium" power version and the "O1" the "upper" version. The "1" indicates that both are the "Technical Update" (TU) versions.
There are just a few hardware differences. For example, the M has a "cylinder head-integrated exhaust manifold" and the O a more traditional "non cylinder head-integrated exhaust manifold". The turbos are also different as a result. Details on the differences between the B58 and B58TU engines, and some information about the differences between the M and O variants in the attached. See pg 5, for example, regarding the different heads.
Now, as to why the X3 M40i has a more powerful engine than the X5 40i, the reason is the "M". Since it's supposed to be a higher-performance vehicle, regardless of the size/weight, it needs more HP to create that effect. And, the tuning is a little more aggressive, which heightens the difference.
Link to Wikipedia -
BMW B58