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      09-26-2013, 04:01 PM   #52
Boss330
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If this is correct, and if it has a 89,6mm bore then there has to be a larger bore spacing than 91mm.

Do you realize how much that affects change in tooling at the engine plant? Longer between crank main bearings, longer between cylinder bores and less space at each end if engine length is the same. Not to mention cyl head tooling.

Again if the info is correct, BMW M must have seen a MAJOR benefit of going this route. Possibly the S55 is the base for a long line of future M engines with larger volume (longer stroke) and therefore makes it economically feasible to develop such a major change from the N55?

But, doing a rough measurement of the N55 block picture, I get a bore spacing of 94mm, leaving a wall thickness of 4,4mm between cylinders with a 89,6mm bore... Where do we have the 91mm bore spacing from?
(Keep in mind that my N55 measurements were very rough and I am open to being mistaken here...)

(Doing a measurement on a picture of the N53 comes up with around 93mm bore spacing, but a very small measurement error at that scale makes a huge difference)

Last edited by Boss330; 09-26-2013 at 04:37 PM..