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post #21 of 58 Unread 31st January 2019, 03:53 PM
sundaycruzers
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Originally Posted by simonnim View Post
Yikes. I hope you didn't take that offensively. I was honestly asking a question.

It makes sense that the total volume being sent through the sprayer would increase over the same period of time. But in my mind how would that affect the bearings with clearances so small. In my mind that's similar to saying let me wash this bean with my sink, but it'll be cleaner if I wash it with a fire hose. I don't understand how surface area can increase with changing oil viscosity.


Not offended, just moving into a speculative subject that everyone disagrees with. When compressing liquids it changes volume of liquid depending on it viscus. After building race engines and some of the insane things we do for hp, Iíve never ran 10w 60 in any race engine...ever. With way large tolerances than 2.5 thousands. The ďwayĒ is an exaggeration. Btw
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post #22 of 58 Unread 31st January 2019, 04:03 PM
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let me preface all this discussion by saying, everything we're saying is speculation. that much is clear. there's ONE guy showing BE bearing showing minimal wear at less than 50k. there may be a couple more, but data point is just not there. we're only deriving what we know about other engines and applying it to s85.

sundaycruzer, i think that using thinner oil with larger gap may lead to oil escaping too quickly leading to journal contact. i don't want to use thinner oil because this engine runs hot @ 210*F which is obviously by design. using thinner oil may have other unforeseen circumstances we don't yet know. from what i see, this is 200k+ engine all day as long as bearings stay lubricated (i'm obviously talking about the short block). i don't want to mess with that.

about the bearings: IN MY OPINION, clevite (BE) bearings don't give enough clearance by the usual ratio i used in other engine builds. TOO MUCH bearing gap from limited knowledge i have, have 2 potential downside. lose oil too quickly leading to low oil pressure and lose oil too quickly leading to journal contact. Upside is that it gives more room for the components to flex and wiggle and leave more room for oil in our s85 cases. i'm not experiencing oil pressure issues with ACL HX race bearings with extra clearance. if i or anyone else can prove that these have no significant wear after a hundred thousand miles, that will prove the second to be true. for now, nobody knows for sure.

i for one certainly think that ACL HX race bearings will have to have less chance of journal contact than BE bearings. with larger gap and no oil pressure issues, there MUST be more oil between the journal and bearing. i would love it if someone proves me wrong. i love learning. time will tell!

2006 E60 M5 with supersprint headers, mid pipe, and muffler without cat. Evolve R stage 3 tune.

Last edited by sunghyun7; 31st January 2019 at 04:04 PM.
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post #23 of 58 Unread 31st January 2019, 04:11 PM
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Originally Posted by sunghyun7 View Post
let me preface all this discussion by saying, everything we're saying is speculation. that much is clear. there's ONE guy showing BE bearing showing minimal wear at less than 50k. there may be a couple more, but data point is just not there. we're only deriving what we know about other engines and applying it to s85.

sundaycruzer, i think that using thinner oil with larger gap may lead to oil escaping too quickly leading to journal contact. i don't want to use thinner oil because this engine runs hot @ 210*F which is obviously by design. using thinner oil may have other unforeseen circumstances we don't yet know. from what i see, this is 200k+ engine all day as long as bearings stay lubricated (i'm obviously talking about the short block). i don't want to mess with that.

about the bearings: IN MY OPINION, clevite (BE) bearings don't give enough clearance by the usual ratio i used in other engine builds. TOO MUCH bearing gap from limited knowledge i have, have 2 potential downside. lose oil too quickly leading to low oil pressure and lose oil too quickly leading to journal contact. Upside is that it gives more room for the components to flex and wiggle and leave more room for oil in our s85 cases. i'm not experiencing oil pressure issues with ACL HX race bearings with extra clearance. if i or anyone else can prove that these have no significant wear after a hundred thousand miles, that will prove the second to be true. for now, nobody knows for sure.

i for one certainly think that ACL HX race bearings will have to have less chance of journal contact than BE bearings. with larger gap and no oil pressure issues, there MUST be more oil between the journal and bearing. i would love it if someone proves me wrong. i love learning. time will tell!


Agreed. I will say there are some known results of wear and longevity of hx and lighter oil but those people have been shun from this forum. Itís unfortunate for us that politics have to ruin the free flow of knowledge.

Iím also using a lower temp thermostat too. Combine all three for a win.
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post #24 of 58 Unread 31st January 2019, 04:11 PM
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post #25 of 58 Unread 31st January 2019, 04:13 PM
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another rod bearing DIY (custom ACL/Lang)

Quote:
Originally Posted by jcolley View Post
This thread is starting to push if not violate some the laws of physics.


Seems quite human.

Edit: your the guru, why is there no evidence of hx bearing wear from you? I imagine that you have pulled a motor apart that had them in it.

Last edited by sundaycruzers; 31st January 2019 at 05:06 PM.
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post #26 of 58 Unread 31st January 2019, 04:18 PM
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Originally Posted by sundaycruzers View Post
Agreed. I will say there are some known results of wear and longevity of hx and lighter oil but those people have been shun from this forum. Itís unfortunate for us that politics have to ruin the free flow of knowledge.

Iím also using a lower temp thermostat too. Combine all three for a win.
I will call utter and complete BS on that statement. As a former moderator here, I've been privy to pretty much every discussion on this forum in the last 12 years even those deleted/locked/hidden The only reason that happens is when members can not follow the basic simple rules of the forum. There are zero politics involved in the exchanges here on behalf of the moderators or admins via sponsors or anyone else.

If someone has posted data and/or evidence on this forum it will remain. It's the exact reason you aren't allowed to edit a post after 24 hours and not one single member has been banned as a result of posting their opinion. It's difficult enough to get people who actually violate forum policy (spam, non-sponsors advertising, commercial links, etc).
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post #27 of 58 Unread 31st January 2019, 04:44 PM
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Quote:
Originally Posted by sundaycruzers View Post
Seems quite human.

Edit: your the guru, why is there no evidence of hx bearing wear from you? I imagine that you have pulled a motor apart that had them in it.
If you mean ACL HX bearings, I have never seen or touched an ACL bearing until the two sets I purchased showed up this week. They may be more popular overseas for S65 and S85s, but not very much in the US.

I purchased two sets (H and HX) which I intend to take measurements on with actual metrology, not Plastiguess. Sunnen GA-2121 with CF-502 setting fixture calibrated against an NIST certifed calibration ring.

My intent is to take a set of readings on H, HX, and a half mixed set which I honestly hope will provide the clearance which matches the ratio recommended by the most prominent and long standing bearing manufacturers.

I have opened 6 engines now with rod bearings that have a larger than OEM clearance and not one of them showed the starvation derived wear pattern described by Clevite. Lets be realistic, the bearing manufacturer is irrelevant, the physics behind it are what matters. One engine was a Dinan stroker and the crank rod journals were manufactured and measured to be .0004 smaller than the OEM crank. One engine was an OEM crank I had reground and polished .0005" undersized. Two were BE bearings/stock crank at 5134 miles and 12k-ish miles. The other was a VAC coated (extra clearance)/stock crank motor at unknown mileage (spun main bearing S65, some time after rod bearing change - S65s are somewhat prone to #1 main failures).

Not one of those engines showed starvation wear, but all showed even wear across the bearing face in the axial direction up to about 1/2" from the parting lines.

I have also removed a set of OEM 702/703 bearings on a stock crank S85 (my own car) with 14k miles on them. These were changed out at 68k miles when I had a stuck injector. The car ran M1 0W-40 the entire 14k miles since bearing change with a 3k OCI and religious warm up routine. Two toddlers in the back for 80% of those 14k miles so no silliness driving. Those bearings *did* exhibit the starvation wear pattern.

While that was only one data point and you can't determine a trend with one point, it was enough for me to say that lowering viscosity alone would not solve the problem.



So, honest questions for those who believe that you can't have too much clearance:
- What would be the engineering purpose for choosing tight oil clearance on a hydrodynamic plain bearing?
- What detrimental effects exist to using excessive clearance *aside* from pressure/flow concerns
- What is the piston to wall clearance specification from BMW for the S65 and S85?

And one more for good measure:
- What are the temperature coefficients of expansion for the engine block and pistons?

Last edited by jcolley; 31st January 2019 at 04:51 PM.
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post #28 of 58 Unread 31st January 2019, 04:47 PM
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Quote:
Originally Posted by sundaycruzers View Post
When compressing liquids it changes volume of liquid depending on it viscus.
Quote:
Originally Posted by jcolley View Post
This thread is starting to push if not violate some the laws of physics.
Oh we're past that. Example #1: to compress a liquid... Given the ridiculously low oil-system pressures we're discussing, liquids are NON-compressible.

As a side note I will quote what one of the best papers I've read about engine lubrication states: the problem with engine oil is that it THINS OUT too much with temperature. Any oil lighter than xW60 exacerbates this problem.
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post #29 of 58 Unread 31st January 2019, 04:51 PM
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Let me fix that:

Quote:
Originally Posted by jcolley View Post
While that was only one data point and you can't make determine a trend with one point, it was enough for me to say that lowering viscosity alone would NOT solve the problem.
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post #30 of 58 Unread 31st January 2019, 04:52 PM
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Originally Posted by flacoramos View Post
Let me fix that:
Edited. For grammar too. Thanks.
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