Official S65 Bearing Specification/Clearance Wiki

[admranger]

Originally Posted by Obioban

My impression is that the WPC treatment is effectively a nano scale shot peening process. If that is correct, I see no reason they couldn't perform nano scale shot peening on micro scale bearing grooves.

Neither do I, but I'd like some proof. There's a lot of proof backing up many of the coatings out there which makes them easy choices for folks to use them for the specific areas they've been tested. The intro to your bolded sentence is the key; "If that is correct..." Once there is some data to prove it is correct, I'll have no issue with it.

[pbonsalb]

Originally Posted by admranger

Neither do I, but I'd like some proof. There's a lot of proof backing up many of the coatings out there which makes them easy choices for folks to use them for the specific areas they've been tested. The intro to your bolded sentence is the key; "If that is correct..." Once there is some data to prove it is corrsect, I'll have no issue with it.

Maybe the coatings fill up the microgrooves. Have not seen any proof that they don't.

[Shredicus]

Originally Posted by pbonsalb

Maybe the coatings fill up the microgrooves. Have not seen any proof that they don't.

Microgrooves only exist on the harder aluminum/tin bearings which are less embeddable than lead babbitt. The grooves are required to flush contaminants from the face of the bearings in lieu of embedding. So if you coat the lead/copper bearings like BE does it's a null argument

[admranger]

Originally Posted by Shredicus

Microgrooves only exist on the harder aluminum/tin bearings which are less embeddable than lead babbitt. The grooves are required to flush contaminants from the face of the bearings in lieu of embedding. So if you coat the lead/copper bearings like BE does it's a null argument

Good point. As long as your using lead/copper bearings, WPC or coat all you want.

[Cleeny]

I'm considering a 2012 or 2013 E92 M3.
I've been lurking and wanted to get the TLDR or summary of this thread since it's long and some of the posts are out of my league quite frankly.
So let me get this straight.
The general consensus or opinion is that only 1 percent of all S65s are affected (the other 99 percent will likely never have bearing issues) and you guys are trying to find out why this is occurring for that 1 percent?

[Sellout]

Here's the general consensus as I see it:

Your bearings are failing. Change them. I know you don't even have an E92 yet, but change your bearings.

That's about the most common feeling I get reading here.

[thekurgan]

Originally Posted by Cleeny

I'm considering a 2012 or 2013 E92 M3.
I've been lurking and wanted to get the TLDR or summary of this thread since it's long and some of the posts are out of my league quite frankly.
So let me get this straight.
The general consensus or opinion is that only 1 percent of all S65s are affected (the other 99 percent will likely never have bearing issues) and you guys are trying to find out why this is occurring for that 1 percent?

You've got 142 pages to go, each page has a tl;dr section. Read.

[Sneaky Pete]

Originally Posted by BMRLVR

Since the main oil pump in the S65 is a variable displacement vane pump it regulates flow based on the system pressure which means that it strokes back (reduces it's displacement) or strokes up (increases it's displacement) as is necessary to maintain pressure nearly constant.

To be completely accurate the oil pump regulates flow based on the oil pressure within the oil pump itself using a simple spring arrangement - not from some point further down the line. Its why the oil pressure is all over the place when not at steady state rpm and the oil flow is always lagging behind demand.

[bigsurge]

Sneaky pete are you suggesting the oil pump is to blame ?

Im not sure if anyone is following the s85 threads on rod bearings, a few guys have pulled their engines apart after running wpc+0w40 and the bearings still looked shot to death so the thinner oil+wpc is a no go plus the s85 has a better more complex and heavier oil system then our s65.

I cant wait until someone opens up an engine with BE bearings and OEM rod bolts +10w60 I bet they'll look good, I am still undecided between VAC and BE since Malek has shown good results with VAC

[Sneaky Pete]

Originally Posted by bigsurge

Sneaky pete are you suggesting the oil pump is to blame ?

Not at all. I've seen it suggested before that the oil pump oil pressure is controlled external to the pump...this is not the case.

Originally Posted by bigsurge

I cant wait until someone opens up an engine with BE bearings and OEM rod bolts +10w60 I bet they'll look good,

Instead I think the BE bearings may well look worse than OEM (all else being equal)...increasing the RB clearance is likely to have the unintended and undesirable consequence of reducing the oil pressure in the RB/journal oil film.

[bigsurge]

Originally Posted by Sneaky Pete

Not at all. I've seen it suggested before that the oil pump oil pressure is controlled external to the pump...this is not the case.



Instead I think the BE bearings may well look worse than OEM (all else being equal)...increasing the RB clearance is likely to have the unintended and undesirable consequence of reducing the oil pressure in the RB/journal oil film.

true, the irony alone would just be epic ahahahah

But wouldn't the oil pump regulate the pressure to optimize for the increased clearance much like when people run 0w40 ?

[Sneaky Pete]

Originally Posted by bigsurge

But wouldn't the oil pump regulate the pressure to optimize for the increased clearance much like when people run 0w40 ?

Who knows - I've seen oil pressure graphs for different oils (on the S65 platform) and they have different peak and average oil pressures.
If you were BMW you could perform all sorts of exhaustive tests to find out the optimum RB clearance and what effects there would be from increasing it.
If you are guessing a clearance for an after market product then you are crossing your fingers, hoping for the best and letting the buyers do the alpha and beta testing.

[Sephiroth]

Originally Posted by Cleeny

I'm considering a 2012 or 2013 E92 M3.
I've been lurking and wanted to get the TLDR or summary of this thread since it's long and some of the posts are out of my league quite frankly.
So let me get this straight.
The general consensus or opinion is that only 1 percent of all S65s are affected (the other 99 percent will likely never have bearing issues) and you guys are trying to find out why this is occurring for that 1 percent?

Start here for an understanding of the bearing clearance theory: http://www.bebearings.com/Overview.html
I will not comment on the other theories. You might even talk to shops, like MRF, about their experiences with bearing replacements.

[Green-Eggs]

We've collected thousands of miles of data logs on oil flow, oil pressure, and engine load. The only data graphs ever been posted and our own thousands of miles of data collected so far all contradict what Pete claims. Pete if you have any data, then you owe the community to post it for all to see.

[BMRLVR]

Originally Posted by Sneaky Pete

To be completely accurate the oil pump regulates flow based on the oil pressure within the oil pump itself using a simple spring arrangement - not from some point further down the line. Its why the oil pressure is all over the place when not at steady state rpm and the oil flow is always lagging behind demand.

Lets talk some basic hydraulics, The pressure in a hydraulic system is constant everywhere in the hydraulic system, meaning the pressure in the main oil gallery of the S65 is the same as the pressure at the pump because the pump is only creating flow, the resistance in the system creates the pressure, I.E. the main, rod, and camshaft bearings, piston cooling jets, timing chain tensioners and cam phasers. excessive leakage at any one of these components will drop system pressure once the pump runs out of additional flow to overcome the leakage. Again, All a pump does is create flow, pressure is the resistance to flow.

The only way for the pressure to be different at some other point in a hydraulic system is if there is an orifice, either variable or fixed that meters the flow (reduces the flow) to a different circuit in the system that requires lower pressure. The orifice allows the main system to run at it's designed pressure and flow yet lowers the flow and pressure to another component that requires less pressure, but these only occur in more complicated hydraulic drive systems that run multiple components requiring different pressures and or pilot controlled systems that run multiple circuits from one pump with pilot control.

I have the lubrication schematic for the S65 in front of me and it is only one circuit with no orifices, either variable or otherwise anywhere, as are most lubrication systems in any engine. By the way, the "oil pressure regulation line" # 24 shows quite clearly on the diagram that it comes right off of the main oil gallery or as BMW refers to it, the Main oil channel #16.

Now I know you are going to try and pick apart my statement above regarding excessive leakage in any of the components fed in the hydraulic system causing pressure drop, and then, you are going to try and relate it to higher clearance bearings causing pressure drop and that BMW designed the bearings tight for a reason. Right? Well, guess what? Ive got the answer for you to that as well....... My 100% stock long block (that will eventually be my stroker) had brand new 702/703 bearings and oem hardware installed and torqued to spec then a high precision flow meter and pressure transducer was fitted and the whole setup has been put in RG's car and driven around and data-logged for the last 6 months in all types of conditions. We have literally millions of lines of data on oil pressure, flow, temperature, throttle position, MAP pressure, RPM, speed, distance travelled, etc and all this data is correlated in a spread sheet and timestamped with box coordinates. One thing I can tell you from all of this data is that the pump in the S65 has lots of headroom where flow is concerned, and in-fact, flows next to no oil <1 GPM at idle and 2-3 GPM at steady cruise yet the pressure stays constant (tight bearing clearance causing low flow? Maybe). However, when throttle position is changed and RPM's are increased and the VANOS units require lots of oil flow to phase the cams, the pump jumps up to >10 GPM. There is a graph that I posted somewhere else on the forums, maybe even in this thread (i can't remember) if you care to look at it.

So the basic jist of this longish post was to say you have not done your homework on hydraulics in general or the S65 lubrication system in particular.
Please brush up on your hydraulic engineering principles and then give me a shout.

[CSBM5]

Originally Posted by bigsurge

true, the irony alone would just be epic ahahahah

But wouldn't the oil pump regulate the pressure to optimize for the increased clearance much like when people run 0w40 ?

A hydrodynamic bearing does not rely on nor have it's oil film strength a function of system oil pressure. All it needs is sufficient oil flow to function as a hydrodynamic bearing.

[bigsurge]

Im just gonna attempt to change the subject here...

How many of you guys that installed VAC bearings made sure that the material was sanded of from the parting lines ?

do most shops know to do this ?

[BMRLVR]

Originally Posted by CSBM5

A hydrodynamic bearing does not rely on nor have it's oil film strength a function of system oil pressure. All it needs is sufficient oil flow to function as a hydrodynamic bearing.

Partially true but not exactly correct. You need to have adequate oil pressure to keep the bearing full of oil, if you don't have adequate oil pressure oil starvation will occur.

You are correct on the fact that the spinning shaft (journal) creates the pressure against the wedge to prevent metal on metal contact.

To the original question, yes the pump will flow additional oil to make up for the reduced viscosity of the 0W40 and will do the same for increased bearing clearance. The pump is flow controlled pressure compensated.

[BMRLVR]

Originally Posted by Sneaky Pete

To be completely accurate the oil pump regulates flow based on the oil pressure within the oil pump itself using a simple spring arrangement - not from some point further down the line. Its why the oil pressure is all over the place when not at steady state rpm and the oil flow is always lagging behind demand.

No it doesn't, in fact it can't.

The pump uses the internal pressure to act on one side of the piston/spring and needs a pressure differential to "stroke up" the pump. If pressure is equal on both sides of the spring the pump displacement stays static.

I'm not sure why you would argue with BMW's own diagram?! The dotted line from the main oil gallery back to the main pump is the signal oil to up or down stroke the pump (according to internationally accepted hydraulic diagram illustration practices, which are recognized by SAE always shows signal or pilot oil passages as a dotted line). It is very clear in the diagram and even numbered and described on the legend.

You sir have no idea what you are talking about and it is clear from the posts that are unsubstantiated and have no evidence. I have thousands of hours of experience on engines and just as much or more with hydraulics and I welcome you to try and disprove me or even BMW's own diagram which I provided for you. I leave emotion or bias out of my posts on here and I post things I have either seen or can support with documentation or my own personal experience.

[CSBM5]

Originally Posted by BMRLVR

Partially true but not exactly correct. You need to have adequate oil pressure to keep the bearing full of oil, if you don't have adequate oil pressure oil starvation will occur.

You are correct on the fact that the spinning shaft (journal) creates the pressure against the wedge to prevent metal on metal contact.

To the original question, yes the pump will flow additional oil to make up for the reduced viscosity of the 0W40 and will do the same for increased bearing clearance. The pump is flow controlled pressure compensated.

Clearly having adequate system pressure is required for sufficient oil flowrate; however, my statement was completely correct -- the oil film strength in a hydrodynamic bearing is not a direct function of system oil pressure. As long as you have enough flowrate, the bearing will function as designed. I was trying to clear up the impression that "oil pressure" in some way directly related to the bearing's performance. The bearing could care less about system oil pressure, meaning it doesn't care if it is 10psi or 100 psi, as long as the bearing receives the oil flowrate it needs to operate.

[BMRLVR]

Originally Posted by CSBM5

Clearly having adequate system pressure is required for sufficient oil flowrate; however, my statement was completely correct -- the oil film strength in a hydrodynamic bearing is not a direct function of system oil pressure. As long as you have enough flowrate, the bearing will function as designed. I was trying to clear up the impression that "oil pressure" in some way directly related to the bearing's performance. The bearing could care less about system oil pressure, meaning it doesn't care if it is 10psi or 100 psi, as long as the bearing receives the oil flowrate it needs to operate.

While I do agree with you partially, it is not 100 % correct. You need more system pressure as RPM increases because of the reasons you stated. If the bearing was sealed what you state is true, but since journal bearings in an ICE are not sealed pressure must be increased as RPM's increase. Please read my reasons why below.

As RPM increases so does the load on the hydrodynamic wedge. As the load increases, the wedge gets thinner and also increases it's pressure. This increase in pressure (in the hydrodynamic wedge or bearing not engine oil pressure) tries to force the oil out of the bearing and it in fact does. This forcing of the oil out of the bearing is why most engines builders like to see oil pressure increase proportionally to engine RPM........ Generally speaking most engine builders look for a minimum of 10 PSI increase in oil pressure per 1000 RPM to ensure all bearings in the engine remain adequately supplied with oil so the hydrodynamic lubrication is maintained.

[swamp2]

There is much more to a proper functioning bearing than just basic flow and pressure... Thermal effects are very important. Higher shear and frictional losses at higher rpm (more power per unit time is produced) demand an increased oil flow rate as to prevent bearings from exceeding an operating temperature limit.