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      05-15-2015, 01:06 AM   #2575
swamp2
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Quote:
Originally Posted by BMRLVR View Post
Well, you are speculating just as much as I am by saying there is no connection between less oil clearance and bearing wear.
I never said that. What I said is that I have not seen any conclusive data in this particular case, nor data for other vehicles. We can all easily abstract to the cases of way out of the norm too tight or too loose of a bearing clearance and both will be disastrous. So certainly there is a connection.

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Originally Posted by BMRLVR View Post
You have admitted that you have no formal assembly nor engineering experience when it comes to engines. I do, and even though I am not an engineer I have hundreds of hours of technicial training specific to engine systems, applied failure analysis, and not to mention hundreds of hours of lubricant training from Exxon/Mobil and Petro Canada and Shell.

Since I have all of this valid training not to mention thousands of hours of engine assembly under my belt, I'd appreciate it if you'd stop discounting everything I post, because quite frankly in my opinion all I see from you is quoting equations and theories from textbooks and online. I agree that your input is valuable, but you have to stop telling everyone how much smarter you are than they are. If both of us had to build an engine I am quite sure I could show you a thing or two, and if we had to engineer a part you could show me. Just give up that condescending tone you have with everyone.
Telling someone they are speculating or or wrong is not the same as condescending. I never made a claim that the widely varying backgrounds present on the forum in general and participating in this discussion aren't highly valuable. In fact I firmly believe just the opposite. However, if I began to lecture or correct you on some aspect of large diesel engine assembly, I'd clearly be out of my domain and although I could be correct, most likely I wouldn't be and very well might get schooled by you. However, when "engine builders" have and continue to make clearly and fundamentally incorrect statements about the math/engineering/physics aspects of this case, it becomes painfully obvious that they too can get outside of their domains of expertise quite quickly. Quoting a respected textbook or equation known to be pretty well exact and accepted is simply a way to engage in evidence based debate.

What would be particularly interesting to me, that you may be able to provide is some shred of data about clearance vs. wear or a comparison of the total maximum allowable range of clearance on other similar engines. Some here have claimed the information is more or less "all over", "easy to find" and just "look it up". I've made some attempts and have come up pretty empty handed. There are quite some differences one must account for in bearing design for diesel engines vs. gasoline. However, the fundamentals of hydrodynamic bearing lubrication are the same.

Quote:
Originally Posted by BMRLVR View Post
P.S.: Remember when you installed your BBK, you didn't even know enough to get the left and right calipers on the proper sides. You put the bleeder screws facing down at the lowest point in the caliper. How did you intend to get all of the air out? Not a small mistake for someone that knows everything!
I certainly claim the opposite, it is relatively inconsequential and certainly in the big picture. Funny thing is that the brakes bled and worked just fine. Obviously that FU was corrected before any hard track use. The flip side of this example is that I did extensive design, engineering, testing and development work for an entirely original and novel bicycle disc brake system. The product was brought to market and successfully sold in volume. One highlight of my engineering contributions to that system was a hollow ceramic piston and custom viton seal which radically reduced heat flow into the brake fluid. I guess the point is that everyone can and does make mistakes. My mistake here neither means I'm a terrible (personal/home) mechanic nor takes away from my various automotive related engineering accomplishments.

With that way too long winded response, let's get back on topic...
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      Yesterday, 09:06 PM   #2576
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Since the people working more closely with the bearing issue are posting within this thread, id like to cross post from another thread to get some feedback from my opinions and observations.

As an outsider looking in, and a new owner of an e90 m3, I would like to comment on the issue at hand after reading this thread in its entirety, and my first post...

Observations:

1. The bearing tolerance spec for the rod bearings, while slightly on the tight side per the .00075" - .001" recommendation, isn't really all that tight when compared to other high revving , race proven, engines. For example, (how dare I compare a honda to bmw, but sorry, ITR's and the like dont just spin rod bearings) Honda ITR motor, B18C5 uses .0013" to .0020" clearance on the rod bearings, and even .0009" to .0017" on mains, it rev's high rpm up to 8400rpm. This motor uses 5w-30........I can assure you, oil pressure and flow is no problem with those tight clearances @ 8400.. And the S2000 F20c engine however is using the 10w30 , is still a 30 weight oil, with tight clearances, and was designed before 5w-30's became more advanced in their shear stability.

Honda has designed some of first, and highest revving n/a engines , s2000 9,000 rpm, gsr 8200, ITR 8400, etc..They don't spin rod bearings like these engines, and use 5w-30 to 10w-30 for the s2k., so how much does all the hype over shear and proper viscosity when hot, really matter between a 60 and a 30 weight oil at high rpm and temperatures?

2. I think where BMW went wrong was trying to achieve a "balance" of race proven oil, and Long life intervals. Or even worse, money..The contractual agreement between castrol and BMW , pure speculation, but i digress..

I believe the choice to run 10w-60 is flawed due to viscosity of 10w-60 at cold starts. Sure 10-60 is great for track use, but how do we know that it is great for the s65? The only way we would know is to see what the oil pressure is at track oil temps, over 250degrees. I would opt to use the lowest weight oil possible to achieve around 80 or so psi which is plenty, @ 8000 rpm.

At high temperatures, you need a heavier weight oil to keep the viscosity up due to extreme heat. However, the bearing clearances as we know, are already fairly on the tight side, the restriction or "resistance" caused by the smaller tolerances, increases pressure to begin with, so does the s65 really need a 60 weight oil to achieve proper pressure and flow, (volume) through such small clearances at higher temperatures?

I believe that this engine, as a daily driver, could even use a 30 weight oil to achieve proper lubrication during high revs and 0w oil during cold starting.

It seems as if most of the rod bearing failures are from cylinders 6-8, per pictures that iv'e seen anyway. Those cylinders are furthest away from the oil pump, coupled with too heavy of an oil at cold start, and the possibility of people not letting the oil reach temperature before driving, could result in the outcomes we are seeing, overtime.

For everyday usage and occasional high rpm driving coupled with the clearances of this motor, and the anecdotal evidence we have with the 0w-40 results, could prove that lighter weight oil is the proper option for the s65.

Now if you plan on tracking the car all day, a heavier weight oil could be the option, BUT, what oil pressures are we achieving with 60 weight, at race temperatures? Is the oil pump constantly on it's relief or whatever means the s65 has to control oil pressure? only someone with a pressure gauge can tell us that....

Lastly, it would be nice to see what tolerances the GTR's and the like are running on their rods, coupled with their oil recommendations of 0w-40, if the tolerances are around the same as our s65's , then why 10w-60 weight? For pure shear tolerance? Is it correct that some 30-40 weight synthetics have just as good shear protection?

I feel as if the 0w-40 option is actually quite correct. I wouldn't go as far as 0w-20 of course...

So that's my opinion.. feel free to flame and correct. HAHAHAHA
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      Today, 09:16 AM   #2577
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Quote:
Originally Posted by tech2351 View Post
Since the people working more closely with the bearing issue are posting within this thread, id like to cross post from another thread to get some feedback from my opinions and observations.

As an outsider looking in, and a new owner of an e90 m3, I would like to comment on the issue at hand after reading this thread in its entirety, and my first post...

Observations:

1. The bearing tolerance spec for the rod bearings, while slightly on the tight side per the .00075" - .001" recommendation, isn't really all that tight when compared to other high revving , race proven, engines. For example, (how dare I compare a honda to bmw, but sorry, ITR's and the like dont just spin rod bearings) Honda ITR motor, B18C5 uses .0013" to .0020" clearance on the rod bearings, and even .0009" to .0017" on mains, it rev's high rpm up to 8400rpm. This motor uses 5w-30........I can assure you, oil pressure and flow is no problem with those tight clearances @ 8400.. And the S2000 F20c engine however is using the 10w30 , is still a 30 weight oil, with tight clearances, and was designed before 5w-30's became more advanced in their shear stability.

Honda has designed some of first, and highest revving n/a engines , s2000 9,000 rpm, gsr 8200, ITR 8400, etc..They don't spin rod bearings like these engines, and use 5w-30 to 10w-30 for the s2k., so how much does all the hype over shear and proper viscosity when hot, really matter between a 60 and a 30 weight oil at high rpm and temperatures?

2. I think where BMW went wrong was trying to achieve a "balance" of race proven oil, and Long life intervals. Or even worse, money..The contractual agreement between castrol and BMW , pure speculation, but i digress..

I believe the choice to run 10w-60 is flawed due to viscosity of 10w-60 at cold starts. Sure 10-60 is great for track use, but how do we know that it is great for the s65? The only way we would know is to see what the oil pressure is at track oil temps, over 250degrees. I would opt to use the lowest weight oil possible to achieve around 80 or so psi which is plenty, @ 8000 rpm.

At high temperatures, you need a heavier weight oil to keep the viscosity up due to extreme heat. However, the bearing clearances as we know, are already fairly on the tight side, the restriction or "resistance" caused by the smaller tolerances, increases pressure to begin with, so does the s65 really need a 60 weight oil to achieve proper pressure and flow, (volume) through such small clearances at higher temperatures?

I believe that this engine, as a daily driver, could even use a 30 weight oil to achieve proper lubrication during high revs and 0w oil during cold starting.

It seems as if most of the rod bearing failures are from cylinders 6-8, per pictures that iv'e seen anyway. Those cylinders are furthest away from the oil pump, coupled with too heavy of an oil at cold start, and the possibility of people not letting the oil reach temperature before driving, could result in the outcomes we are seeing, overtime.

For everyday usage and occasional high rpm driving coupled with the clearances of this motor, and the anecdotal evidence we have with the 0w-40 results, could prove that lighter weight oil is the proper option for the s65.

Now if you plan on tracking the car all day, a heavier weight oil could be the option, BUT, what oil pressures are we achieving with 60 weight, at race temperatures? Is the oil pump constantly on it's relief or whatever means the s65 has to control oil pressure? only someone with a pressure gauge can tell us that....

Lastly, it would be nice to see what tolerances the GTR's and the like are running on their rods, coupled with their oil recommendations of 0w-40, if the tolerances are around the same as our s65's , then why 10w-60 weight? For pure shear tolerance? Is it correct that some 30-40 weight synthetics have just as good shear protection?

I feel as if the 0w-40 option is actually quite correct. I wouldn't go as far as 0w-20 of course...

So that's my opinion.. feel free to flame and correct. HAHAHAHA
You've not written one word that wasn't already mentioned here for the past few years. Welcome to the board.
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