Quote:
Originally Posted by serranot
BE has a working theory supported by its data.
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But thats the problem...the theory isn't supported at all by "real world" data.
For example: If the S65's RB clearance specification is insufficient how are engines rebuilt with factory RB clearance able to cover high mileage and have bearings in good condition upon disassembly?
If the S65's factory RB clearance specification is insufficient such that it causes engine failure then most S65 engines should have already failed, not just a small %.
In any search for a theory to explain a phenomenon, you look for the simplest and neatest theory that satisfies all the noted outcomes. Not one that requires numerous logical contortions, a complete disregard of common sense while at the same time failing satisfy any of the outcomes other than engine failures are often likely to have an insufficient RB clearance component.
BEs tight factory RB clearance theory is a classic example of confirmation bias with extra pretzel logic on the side.
Quote:
Originally Posted by ksteckba
To be fair, any argument made that BMW could have easily changed the bearing specs from the S85 to the S65 is completely disregarding the legal implications of such a fundamental design change. If they did make a significant bearing design change for the S65 and a class action suit was filed for the S85 owners, then how do you think the outcome would be affected?
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Yet BMW in fact did indeed make many fundamental changes to the S85 design when building the S65 platform. Not least, hardware changes to the ionic anti knock system, a complete vanos redesign, a new lubrication system and of course a new crank.
BMW had the ideal opportunity during the S65 design to make any bearing clearance changes that they deemed necessary. If they were at all concerned about the legal implications they would simply keep the same RBs as used in the S85 (which they did IIRC) and machine the S65s new crank to give whatever clearance they desired....balancing out the new lubrication system to ensure other parts, such as the main bearings, were not compromised by increasing oil flow through the RBs.
The change would be invisible as BMW do not release proprietary information such as the RB specifications for these engines to the public domain and the new (shortened) crank would have a new part number.
Its not inconceivable that the blueprinted hand built pre production S65 engines performed perfectly well during extensive endurance and climate testing. But during the process of automating the engine building aspect of manufacture and/or in the production of the rod bearings by clevite, tolerance control was compromised. Such that at one end of the scale, engines with the correct specified factory RB clearance would be able to cover high mileage without problem while at the other end of the scale, engines with out of tolerance RB clearance would fail at low mileage. The majority of engines being spread somewhere along the spectrum.