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Old Wed, Aug-22-2018, 06:04:47 PM   #10
HassanEido
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Default Re: Any S54 Rebuild Tips/Advice?

Quote:
Originally Posted by J. Beez View Post
Can we have the “long version” on BE Bearings? Just curious :P


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Ok. Long version.
Bearing failure on the s54 is typical of any high rpm engine. In fact it betters engines with similar redlines and requires a rod bearing change typically from 80 to 130k miles depending on driving styles and other factors. None of these factors include bearing clearance, since the s54,unlike the s65 and s85, has typical bearing clearance.
BE made their reputation increasing the bearing clearance on the s65 and s85 engines. This is counter productive on the s54 for the following reasons:
1- There is no problem to be fixed here,bearings as mentioned before have typical clearance
2- increasing clearance lowers oil pressure. I assume u know oil pressure is the only thing protecting bearing/crank surfaces as the bearing rides on a film of pressurized oil. Pressure drops, bearings hit crank journal metal and kaboom. Seriously. Think hovercraft but with oil.
3- If clearance was the issue,it would be a self rectifying problem. In engineering we call this a self rectifying feedback loop. Since with age, surfaces wear, clearance is increased and voila problem fixed! Only it's not, as now wear will accelerate as oil pressure has dropped.
4-Coating and surface treatment to retain oil does not help, as only the presence of oil or a lubricant doesn't prevent bearing wear, only pressurized oil will.
5-They're more expensive than OE bearings which will go a really long way,so no need for them, even if they did offer an improvement,which they don't.
There. That's why.
Cheers
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Why not to use after market bearings with surfacetreatments and /or increased clearance
http://www.m3forum.net/m3forum/showp...4&postcount=10

Last edited by HassanEido; Wed, Aug-22-2018 at 06:17:48 PM.
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