Official S65 Bearing Specification/Clearance Wiki

[BMRLVR]

Originally Posted by swamp2

This is fantastic. My concerns about the validity of any testing is keeping things apples to apples. I'm sure you/RG/kawasaki don't want any "lectures" or heck even friendly advice on the topic but in order to have any credibility a test must have some adequate control. At it's most basic level one needs to have an engine, preferably both always stock and one that was disassembled and had significant and premature bearing wear present. Then with NO CHANGES other than the redesigned bearings, an attempt should be made to operate the car in as similar of a fashion as it was prior with the factory bearings. It would also be a great idea to replace the bearings with stock ones again and see if roughly the same wear can be duplicated. The duration of a meaningful test here presents some obvious difficulties. I applaud all of you involved in this effort and certainly hope you can conduct some testing with such simple but crucial controls in place. Too many things changing at the same time will immediately invalidate test results. And I can only imagine the urge to, try this rod, that bolt, this coating, that oil, etc.

RG is going to be conducting the testing and although he has discussed it with me, he will be handling the details. One thing I can tell you for sure is that the only change in the engine will be the bearings, everything else will be OEM. I am quite sure the whole thing will be well documented and the findings posted in a well organized manner as is the rest of the info in this thread.

[BMRLVR]

Originally Posted by s85e90

A lot of so called experts here who could theoretically design a better engine than BMW.

No one is intending to design a better engine or claiming they could. What people are claiming is that they feel they could select a more appropriate oil clearance for the S65. An engine that wears through the overlay of the rod bearings in 60,000 miles or less is just not acceptable.

[Petros]

Originally Posted by BMRLVR

RG is going to be conducting the testing and although he has discussed it with me, he will be handling the details. One thing I can tell you for sure is that the only change in the engine will be the bearings, everything else will be OEM. I am quite sure the whole thing will be well documented and the findings posted in a well organized manner as is the rest of the info in this thread.

why not put the engine on an engine dyno? THis way you can mimic running an engine for tens of thousands of kilometres without having to put it in a car and drive it around

[regular guy]

Originally Posted by Petros

why not put the engine on an engine dyno? THis way you can mimic running an engine for tens of thousands of kilometres without having to put it in a car and drive it around

You would need the ECU and half the car's electronics and wiring harnesses just to make it work. This is why nobody does this, and they all use a Motec or similar stand-alone ECU when they put one on an engine dyno. Also engine dyno time is typically $1000 per day. Running for tens of thousands of KMs would be cost prohibitive and wouldn't be as fun as driving the car.

[regular guy]

Originally Posted by SenorFunkyPants

King Bearings have been using "ENSIM" for a while, I expect Clevite would have something similar.
http://www.kingbearings.com/rd/ensimtm/
In this application the software is used to optimise bearing clearances and crucially the bearing eccentricity, based on inputs such as crank journal diameter, oil input temp, oil viscosity, bearing loads, engine rpms etc.
Then as noted BMW spend $$$millions in real world testing the theoretical numbers in engines on rigs including to destruction and in extreme temperature environments...cross checking against data from the S85.
No reason to believe that you couldn't arrive at a much better result using the internet and chatting with a few pals.

Are you so sure BMW spent millions of dollars in real world testing of 702/703 bearings? Can you provide any proof?

Also, in your opinion, who's a better bearing designer: Clevite or King? They have quite different approaches to bearing eccentricity, and the Clevite bearings seem to last longer than the King's. Could this be (yet) another example of how real world designs are different (and often better) than purely theoretical ones?

[SenorFunkyPants]

Originally Posted by regular guy

Are you so sure BMW spent millions of dollars in real world testing of 702/703 bearings? Can you provide any proof?

Apparently I misspoke...I've just been messaged by Wolfgang Von Hfuhruhurr (head of M Division R&D) - he said they were a bit short of petty cash that day, so they settled for sending the job experience boy out in the S65 mule down to McDonalds to get lunch. It came back in one piece so they decided they were good to go.

[regular guy]

Originally Posted by SenorFunkyPants

Apparently I misspoke...I've just been messaged by Wolfgang Von Hfuhruhurr (head of M Division R&D) - he said they were a bit short of petty cash that day, so they settled for sending the job experience boy out in the S65 mule down to McDonalds to get lunch. It came back in one piece so they decided they were good to go.

LOL.

I think I remember seeing that kid down at the McDonalds in the Mojave Desert when he was doing the testing.

[CSBM5]

Originally Posted by Petros

why not put the engine on an engine dyno? THis way you can mimic running an engine for tens of thousands of kilometres without having to put it in a car and drive it around

You'd need to do that in an environmental chamber so you could allow a large number of cold starts from various initial states, initial conditions (i.e. fully steady state cold starts which take a good while for the engine to cool to that state), etc.

Hence you would need to come up with an operating profile for a "typical" S65 as used in normal operation. It would need to mimic not only cold starts, warm starts, but also the continuous dynamic operation of the engine as opposed to relative constant rpm stuff.

None of that would be cheap. Setting up a properly designed test with careful control of variables and then actually running such test would run into serious time and money...

[regular guy]

Originally Posted by swamp2

They've (BMW) obviously already done the "Pelican Brief" math here. Seems readily apparent that nothing "needs" rectified. Sure, I'd be quite bummed and even a bit pissed if I threw a rod or similar. However, that's why I personally have an extended warranty. And no, the decision to purchase that had nothing to do with any potential bearing problem. It was largely based on engine/transmission replacement costs, nothing more.

Let me add another flavor to the Pelican Brief math. The same thing holds true for civil engineering. (I sat on my local planning commission and had to read these studies.) When a city (or state) builds a road or a bridge, they calculate how much it costs for 2-lanes, 3-lanes, 4-lanes, etc. Let's take the bridge building example because it's much more expensive than building roads. The city/state calculate how much it will cost to build each version of that bridge, even if it's 70% utilized and 30% traffic-jammed the day they complete it. Then they project population increases and model how much more traffic can go across that bridge, until the bridge and all other affected areas like side streets, on ramps, etc. have unbearable traffic jams that the citizens won't tolerate. If that time delta is 20 years, then the city will calculate how much it will cost to expand the bridge 20 years from now, adjusted for inflation. Then they decide which version of the bridge they want to build. So the same thing plays out in civil engineering as well.

This is fantastic. My concerns about the validity of any testing is keeping things apples to apples. I'm sure you/RG/kawasaki don't want any "lectures" or heck even friendly advice on the topic but in order to have any credibility a test must have some adequate control. At it's most basic level one needs to have an engine, preferably both always stock and one that was disassembled and had significant and premature bearing wear present. Then with NO CHANGES other than the redesigned bearings, an attempt should be made to operate the car in as similar of a fashion as it was prior with the factory bearings. It would also be a great idea to replace the bearings with stock ones again and see if roughly the same wear can be duplicated. The duration of a meaningful test here presents some obvious difficulties. I applaud all of you involved in this effort and certainly hope you can conduct some testing with such simple but crucial controls in place. Too many things changing at the same time will immediately invalidate test results. And I can only imagine the urge to, try this rod, that bolt, this coating, that oil, etc.

Believe me, I know how to keep all variables the same. Basic plan is put a bone stock motor in my car, with bone stock software, exhaust, etc. and brand new factory bearings. I've got a few motors to choose from, but I plan to use the one BMRLVR sent down for a stroker build next year.

I've just bought a real fancy oil flow meter from Flow Technologies that is both temperature and oil viscosity adjusted/calibrated over the entire range of S65 operating parameters (for both temperature and oil viscosity). I also have an oil pressure sensor, and oil temperature sensor. All of these can data log up to 100 Hz, but realistically it will be 10Hz because my A2D converter only samples at 10Hz and injects the data onto the MSS60 ECU CAN bus where I can capture it and everything on the ECU can bus.

I'd drive the car about 3 months while data logging and downloading the data logs the entire time. The car would attend at least one track day, most likely at Laguna Seca since that's closest to me. I'm specifically looking how oil flow and temperature change with RPM, whether pressure and flow drops during hard corning at the track, etc. Remove the bearings and inspect them. Post the results and make all data available for download.

Then switch to the new extra clearance Clevite bearings when they come in and do the whole thing all over again. Remove bearings, inspect, post all data, etc.

When that's done, I'm thinking of doing something really crazy. I still have that 1/2 set of virgin 088/089 Clevite bearings. I'm thinking of placing that half set on cylinders 1, 3, 5, 7, and another new half set of extra clearance Clevite bearings on cylinders 2, 4, 6, 8. Drive the snot out of it. Remove bearings, and compare side-by-side. Post pictures, data, etc.

Then when that's done, put in another new set of Clevite bearings, and add a dry sump. Repeat the process, post results.

[pbonsalb]

Wouldn't any bearing look fine after just 3 months?

[regular guy]

Originally Posted by pbonsalb

Wouldn't any bearing look fine after just 3 months?

The purpose is to quell or add fuel to the debate about oil flow vs. viscosity and bearing clearance. Three months on each should be enough data to shed some meaningful light on that topic.

[Yellow Snow]

Originally Posted by regular guy

The purpose is to quell or add fuel to the debate about oil flow vs. viscosity and bearing clearance. Three months on each should be enough data to shed some meaningful light on that topic.

Gee. I wonder what the results of this completely unbiased analysis will be.

[regular guy]

Originally Posted by Yellow Snow

Gee. I wonder what the results of this completely unbiased analysis will be.

Data is data, so I don't know how it can be biased. You've been the habitual data falsifier in this thread, why don't you tell us how it will turn out before any measurements are taken?

[jcolley]

Speaking of the white paper, I noticed the link was dead as well. Anyone have a copy to post back here?

[regular guy]

Originally Posted by jcolley

Speaking of the white paper, I noticed the link was dead as well. Anyone have a copy to post back here?

http://www.mahle-aftermarket.com/med...s/eb-40-14.pdf

I've also updated the link on Post #2 of this thread.

[swamp2]

Originally Posted by SenorFunkyPants

King Bearings have been using "ENSIM" for a while, I expect Clevite would have something similar.
http://www.kingbearings.com/rd/ensimtm/
In this application the software is used to optimise bearing clearances and crucially the bearing eccentricity, based on inputs such as crank journal diameter, oil input temp, oil viscosity, bearing loads, engine rpms etc.
Then as noted BMW spend $$$millions in real world testing the theoretical numbers in engines on rigs including to destruction and in extreme temperature environments...cross checking against data from the S85.

And the OEMs almost assuredly have techniques even more powerful, predictive and accurate than their suppliers (at least on this topic). I just read some paper abstracts about a way to model elasto-thermo-hydrodynamics for bearing lubrication. This means the rod big ends are not assumed rigid but move/distort as they do from inertial loads and load transfer through the oil. Then fluid dynamics, pressures, minimum film thickness, wedge formation, journal whirl and temperature rise of the oil through 1 "pass" through a single bearing can all be determined. This was being done in the 80's...

Originally Posted by SenorFunkyPants

No reason to believe that you couldn't arrive at a much better result using the internet and chatting with a few pals.

Indeed. I've got a big philosophical problem running a part as critical as an engine bearing designed with a rule of thumb plus .001" (or whatever similar "design technique" will be used in this case). Now that being said, I can also be reasonable enough to let good testing override/veto such concerns. The flip side is though perhaps being right for the wrong reason, which can be quite common with such "design techniques". It's almost better to be wrong but for the right reason, because from there, one can surely get to also being right for the right reason.

[swamp2]

Originally Posted by regular guy

Let me add another flavor to the Pelican Brief math. The same thing holds true for civil engineering. (I sat on my local planning commission and had to read these studies.) When a city (or state) builds a road or a bridge, they calculate how much it costs for 2-lanes, 3-lanes, 4-lanes, etc. Let's take the bridge building example because it's much more expensive than building roads. The city/state calculate how much it will cost to build each version of that bridge, even if it's 70% utilized and 30% traffic-jammed the day they complete it. Then they project population increases and model how much more traffic can go across that bridge, until the bridge and all other affected areas like side streets, on ramps, etc. have unbearable traffic jams that the citizens won't tolerate. If that time delta is 20 years, then the city will calculate how much it will cost to expand the bridge 20 years from now, adjusted for inflation. Then they decide which version of the bridge they want to build. So the same thing plays out in civil engineering as well.

Not sure I understand you point here...

Originally Posted by regular guy

Believe me, I know how to keep all variables the same. Basic plan is put a bone stock motor in my car, with bone stock software, exhaust, etc. and brand new factory bearings. I've got a few motors to choose from, but I plan to use the one BMRLVR sent down for a stroker build next year.

I've just bought a real fancy oil flow meter from Flow Technologies that is both temperature and oil viscosity adjusted/calibrated over the entire range of S65 operating parameters (for both temperature and oil viscosity). I also have an oil pressure sensor, and oil temperature sensor. All of these can data log up to 100 Hz, but realistically it will be 10Hz because my A2D converter only samples at 10Hz and injects the data onto the MSS60 ECU CAN bus where I can capture it and everything on the ECU can bus.

I'd drive the car about 3 months while data logging and downloading the data logs the entire time. The car would attend at least one track day, most likely at Laguna Seca since that's closest to me. I'm specifically looking how oil flow and temperature change with RPM, whether pressure and flow drops during hard corning at the track, etc. Remove the bearings and inspect them. Post the results and make all data available for download.

Then switch to the new extra clearance Clevite bearings when they come in and do the whole thing all over again. Remove bearings, inspect, post all data, etc.

When that's done, I'm thinking of doing something really crazy. I still have that 1/2 set of virgin 088/089 Clevite bearings. I'm thinking of placing that half set on cylinders 1, 3, 5, 7, and another new half set of extra clearance Clevite bearings on cylinders 2, 4, 6, 8. Drive the snot out of it. Remove bearings, and compare side-by-side. Post pictures, data, etc.

Then when that's done, put in another new set of Clevite bearings, and add a dry sump. Repeat the process, post results.

Sounds like a reasonably good plan. This is exciting and obviously represents a huge commitment in time and expense. Hopefully premature wear will actually be seen after such a relatively low mileage on the first control run with factory bearings.

That being said, I'm not sure that the oil pressure and temperature information will provide any meaningful information about the detailed hydrodynamics inside the journal bearings. I'm not entirely convinced of the value and predictive capability of oil analysis but I'm sure you'll be doing that as well. Have you decided what oil change interval you be using? Have you considered putting on some soft miles as well as hard ones?

I suggest you do try to achieve a similar broad spread in both the control test and new design test for the clearances (i.e. purposefully hand matching the bearings to the journals to get as wide of a variation in clearance as possible. I'm sure you've already considered that.

Running half OEM and half redesigned bearings sounds pretty clever as well but certainly not in place of the tests with all OEM or all redesigned bearings.

As I did for one of the big measurement endeavors, I would be willing to donate some funds for this kind of effort. I think you could definitely find some additional supporters who feel the same. Heck even enough donations to cover the oil for the oil changes would be nice...

[Killerfish2012]

Meanwhile, in the track section...........

http://www.m3post.com/forums/showthread.php?t=1140841

[regular guy]

Originally Posted by Killerfish2012

Meanwhile, in the track section...........

http://www.m3post.com/forums/showthr...ster?t=1140841

Yes, meanwhile in the track section...another guy two weeks earlier, also at Laguna Seca puked a rod and put three holes in the block. Is he on the forum? No. Will he post it on the forum? No. Is it under warranty? I don't know. Was low miles, something like 30k or less, and 2012 model year I believe.

Just curious, were you the guy who a few weeks ago kept saying there wasn't a single blown motor reported by track guys? If you're not, then no worries. Whoever it was, I thought it was kind of funny because there have been many motors blown while on the track and I've seen a few of them reported. I reported two myself (not counting this one). So whoever said it, wasn't very informed...or a troll (which is usually uninformed by nature).

[swamp2]

Originally Posted by WhatsADSM

What "advantages" are we talking about?

1. Smaller clearances actually provide for an increased peak load handling capability. I just posted on this in the last couple of days. The same claim is made in another post I made here in this thread from a different source

"Objections to a large [bearing] clearance include a reduction in the value of the Sommerfeld number and hence a lower factor of safety against oil film breakdown".

Source - "Reciprocating Machinery Dynamics" by A.S. Rangwala,

2. Directly from Clevite (not sure I buy this from a practical perspective), but straight from the horses mouth "they [tighter clearances]; 1) spread the load on the oil film out over a wider area, reducing the psi load on the film and reducing the chances for boundary or mixed lubrication conditions and 2) allow longer engine/bearing life."

3. Looser clearances can also result in oil starvation.

4. Bearing clearance affects NVH but it is purely speculative if smaller clearances are beneficial for NVH.

Originally Posted by WhatsADSM

It sure sounds like the most reasonable theory coming out here is that BMW set the nominal tolerance pretty tight. Not necessarily impossible just tight. Then after a nominally tight tolerance they don't have the manufacturing process to a level of refinement that can actually hold the variations where they want them.

Tolerances are a huge gray area. If you need to hold an arbitrarily good tolerance you pretty much can, cost just rises and often times does so exponentially. Thus cost and manufacturing are traded off against required engineering specification for performance/safety/lifespan.

If you think BMW did not both specify and monitor through QA EXACTLY what tolerance was present is every single component contributing bearing clearance then all I can say is that you really don't understand nor appreciate modern precision engineering and manufacturing.

Really, do you think the engineers said, I need +/- 0.0002", put that on their drawings, gave that to manufacturing. Manufacturing turned around after the fact and said, well we can't give you +/-0.0002" but how does double that sound, +/-0.0004" and both departments just said, OK, let's roll the dice? No, didn't happen, period. This stuff gets "bargained" for through design and cost "trades studies" in the R&D phase and all parties agree on what will be speced and delivered. Non conforming parts are reworked if possible or scrapped, period.

[regular guy]

Originally Posted by swamp2

Not sure I understand you point here...

The point was that Pelican Brief math (I like that phrase), shows up in more places than manufacturing and product liability. The example I gave was in Civil Engineering.

Sounds like a reasonably good plan. This is exciting and obviously represents a huge commitment in time and expense. Hopefully premature wear will actually be seen after such a relatively low mileage on the first control run with factory bearings.

That being said, I'm not sure that the oil pressure and temperature information will provide any meaningful information about the detailed hydrodynamics inside the journal bearings. I'm not entirely convinced of the value and predictive capability of oil analysis but I'm sure you'll be doing that as well. Have you decided what oil change interval you be using? Have you considered putting on some soft miles as well as hard ones?

I suggest you do try to achieve a similar broad spread in both the control test and new design test for the clearances (i.e. purposefully hand matching the bearings to the journals to get as wide of a variation in clearance as possible. I'm sure you've already considered that.

Running half OEM and half redesigned bearings sounds pretty clever as well but certainly not in place of the tests with all OEM or all redesigned bearings.

As I did for one of the big measurement endeavors, I would be willing to donate some funds for this kind of effort. I think you could definitely find some additional supporters who feel the same. Heck even enough donations to cover the oil for the oil changes would be nice...

BTW, I've got to call shame on you for thinking something like this wouldn't have been done. I had already been planning this and getting price quotes on flow meters on the day you proclaimed that you would bet no testing would ever be done on the new bearings. Not trying to start something...just saying that was the plan all along.

I also appreciate the offer for a fundme, but I'm not sure it's necessary. I think the business responsible for the bearings will be funding the labor and the Clevite bearings. I'd only be funding the stock bearings as far as I know. But I could be making some bad assumptions...but that's what I'm lead to believe. If it does end up being necessary, I'll let you know.

So just out of curiosity, who here thinks VAC put anything near this amount of effort into their Clevite bearings? NOTE: SFP proclaimed in another thread that has no issue with VAC Clevite bearings...but these Clevite bearings bother him.

[regular guy]

Originally Posted by swamp2

Really, do you think the engineers said, I need +/- 0.0002", put that on their drawings, gave that to manufacturing. Manufacturing turned around after the fact and said, well we can't give you +/-0.0002" but how does double that sound, +/-0.0004" and both departments just said, OK, let's roll the dice? No, didn't happen, period. This stuff gets "bargained" for through design and cost "trades studies" in the R&D phase and all parties agree on what will be speced and delivered. Non conforming parts are reworked if possible or scrapped, period.

I've got to be honest swamp, that sounds like a distinction without a difference. That exact bargaining process is what ends up with one side saying "yeah, we'll go along with that." At least that's how I see it.