Scary rod bearing thread s85

[s62]

I came across this while perusing a training document for another popular V10 engine (emphasis mine):

Oil Circulation

The oil supply in the 5.2L V10 engine is based on
a traditional wet sump concept. The focal point of
development was on significant reduction of the oil flow
rate through tighter bearing tolerances. With a lower flow
rate, the oil remains in the sump longer and is able to
recover from aeration better.

At an oil temperature of 248°F (120°C), the flow rate of
58 qts (55 liters) per minute at 7000 RPM is very low for a
10-cylinder engine. This has helped to minimize oil pump
drive power requirements and improve fuel economy.

If you'd like the download link, please pm

[206_m3]

Has anyone looked into VAC bearing kit for a better solution to bearing failure

[BMRLVR]

Originally Posted by 206_m3

Has anyone looked into VAC bearing kit for a better solution to bearing failure

Try going back and reading the thread! That has been covered already

[happos2]

Originally Posted by BMRLVR

Try going back and reading the thread! That has been covered already

We appreciated your input and knowledge.

To make this thread useful, I wish we would just delete all the bogus stuff Longwong has been stating because there are about 5 useful pages of thread and 18 bickering. Moderators?

[kawasaki00]

Originally Posted by Team Plutonium

Dear lord, I just saw this gem of a post.

Makes me want to stab myself in the eye with a fork.

[1MOREMOD]

Originally Posted by Team Plutonium

Dear lord, I just saw this gem of a post.

i rather liked it.

[lsal]

Originally Posted by 1MOREMOD

i rather liked it.

You definitely found your oil guy for the team!!!

[regular guy]

Originally Posted by 206_m3

Has anyone looked into VAC bearing kit for a better solution to bearing failure

Yes this has been covered. In a nutshell, here's the answer. According to the coating manufacturer, the coated bearings add between 0.0002 - 0.0004 thickness to the surface of the factory bearing. With clearance already too small at 0.001", this means you will reduce your existing bearing clearance by 20-40% just by installing the coated bearings.

If you have stock main/rod journal sizes, the recommendation is to stay away from the coated bearings as this will make the clearance problem worse, not better. However if you have resized your main/rod journal sizes to add additional clearance, then the coated bearings might be very nice.

[Longboarder]

Originally Posted by 1MOREMOD

A sphincter says what.

uhhh what?

[VCMpower]

Nice! Some humor to end this exhausted thread.

Originally Posted by Longboarder

uhhh what?

Originally Posted by 1MOREMOD

A sphincter says what.

[206_m3]

Originally Posted by regular guy

Yes this has been covered. In a nutshell, here's the answer. According to the coating manufacturer, the coated bearings add between 0.0002 - 0.0004 thickness to the surface of the factory bearing. With clearance already too small at 0.001", this means you will reduce your existing bearing clearance by 20-40% just by installing the coated bearings.

If you have stock main/rod journal sizes, the recommendation is to stay away from the coated bearings as this will make the clearance problem worse, not better. However if you have resized your main/rod journal sizes to add additional clearance, then the coated bearings might be very nice.

interesting.... i didn't know that. I was talking to a vendor on here about super charging the car and indicated that using the VAC bearing kit along with the arp studs and all will help reduce bearing failure, but as you said the thermal coating will get in the way of clearance issues. So is there even a clear cut solution to this?

[W///]

Originally Posted by 206_m3

interesting.... i didn't know that. I was talking to a vendor on here about super charging the car and indicated that using the VAC bearing kit along with the arp studs and all will help reduce bearing failure, but as you said the thermal coating will get in the way of clearance issues. So is there even a clear cut solution to this?

Again this has been covered already. Can't get bearings that are smaller, so you'd have to get the proper gap. Which is no easy task.

Therefore, for us non-supercharged folks, some of us will run thinner oil to help it a little.

Just go through the thread and ignore everyone apart from BLMVR, Kawasaki and Regular Guy (forgot some other people).

[206_m3]

Originally Posted by W///

Again this has been covered already. Can't get bearings that are smaller, so you'd have to get the proper gap. Which is no easy task.

Therefore, for us non-supercharged folks, some of us will run thinner oil to help it a little.

Just go through the thread and ignore everyone apart from BLMVR, Kawasaki and Regular Guy (forgot some other people).

thanks! i have read through most of it but not all of it. I really want to supercharge this car but after reading all these things I have been very scared to.

[VCMpower]

No doubt.

Originally Posted by 206_m3

thanks! i have read through most of it but not all of it. I really want to supercharge this car but after reading all these things I have been very scared to.

[GIdriver]

Originally Posted by kawasaki00

Makes me want to stab myself in the eye with a fork.

[lsal]

Originally Posted by Lute

As did I, he's definitely keeping me on top of my gif game

You inspire me...

[CSBM5]

Some interesting articles on bearings:

http://www.precisionenginetech.com/t...g-tech-part-1/

http://www.precisionenginetech.com/t...g-tech-part-2/

http://www.precisionenginetech.com/t...g-tech-part-3/

[US///M3]

Originally Posted by Longwong

Oil pressure is certainly part of the decision of which oil to run but certainly only one component and the weights are chose for a variety of other reasons including clearences, engine design etc. Many oils and weights offer equal oil pressure given any modern variable oil pump so just because one oil offers the same pressure it does not mean the oil is totally compatible. However you need an oil that runs the same pressure to be compatibile. Those are not the same two things however.

And actually the mobile 0w50 weight is not nearly as relevant even if it sheers to 40 which there is no data on because it has 1600 ZDDP which is the entire point. Lighter oil with much higher anti-friction zddp which is an equally effective barrier from metal-metal contact. Oil weight is another important factor but not the only one. Plus you are using a 0w40 weight so not sure what your point is that it sheers down to a 40 when you are recommending a 40? Only the 0w40 you are using has 600 zddp level which is a third of the mobil 1 R oil which means you have minimal protection at hard temps

.

[OC ///M]

Originally Posted by CSBM5

Some interesting articles on bearings:

http://www.precisionenginetech.com/t...g-tech-part-1/

http://www.precisionenginetech.com/t...g-tech-part-2/

http://www.precisionenginetech.com/t...g-tech-part-3/

Good info there, thanks for posting the links here, CSB.

[GIdriver]

Originally Posted by CSBM5

Some interesting articles on bearings:

http://www.precisionenginetech.com/t...g-tech-part-1/

http://www.precisionenginetech.com/t...g-tech-part-2/

http://www.precisionenginetech.com/t...g-tech-part-3/

Thanks for sharing!

[Voltigeur]

Originally Posted by Longwong

Can someone summarize what we have learned here for us mere mortals? What my take away is

1. The issue is bmw made the clearence for oil to properly lubricate the bearings so ridiculously small because speculation that they were doing it for noise reduction or increase in power? At the expense of not having enough clearence for the thick oil they recommend

2.Mahle recommends 5w30 with the clearences bmw is using. So why don't we all switch to 5w 30? Can someone explain the cost vs benefit of those who don't know how 5w 30 may hold up at 8k rpm?

3. No point to coated bearings for 2 reasons. First it may worsen the problem since the coating further reduces the clearences. Second even if not, it still does not fix the problem of under lubrication and the coated ones will fail as well

Thank you. I too am not highly educated in the area of engine tolerances and oils etc. Just a concerned owner who wants his M3 to last.

Originally Posted by Longwong

So is there literally nothing anyone can do?

Honestly with this information I cannot see how anyone in their right mind would supercharge this car. I was going to but no way in hell now.

Any particular driving habits worse for bearing starvation? Is it a high rpm issue ...Can someone explain

[ChrisK]

I got my blackstone-labs report. All looks good - No LEAD!

2011 e92 M3
Stock Oil
Miles on the car: 18k
Miles on the oil: 6.3K

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