Quote:
Originally Posted by Green-Eggs
There's a new and "shocking" development for the people following this thread and the BMW S65 rod bearing issue. After 10+ years, BMW has finally published their rod bearing clearance specifications. To put it mildly, the specs are shocking and are worse than we had imagined.
Every time a new TIS is published, Bert checks to see if BMW has finally published the rod bearing clearance specs. Such was the case last week when Bert was researching the rod bearing specs for S63 motor. That's when Bert pulled up the S65 engine specs, and noticed that they finally contain rod bearing clearance. [ LINK]
The specs aren't good and confirm a worse-than worst case scenario. When Van Dyne measured the original bearings @ 0.0013 inch, they didn't imagine that was at the top end of the clearance specs. Stewart Van Dyne gave the following comment over the phone: "Well, BMW just confirmed that they're doing what we all know doesn't work."
Minimum clearance: 0.0004 inch
Nominal clearance: 0.0009 inch
Maximum clearance: 0.0013 inch
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So the obvious question becomes even more salient:
Why?
If it's true that tight rod bearing clearance was a mistake on this engine, this development means the mistake was even greater than previously believed. That makes it even harder to escape the binary choice: either the M Division was spectacularly incompetent here, neglecting or forgetting noob-level basics of engine building, or there's something --
something -- that explains their choice.