BE Bearings In-Depth: Oil Flow, Oil Pressure Analysis

[noremaC]

What is the recommendation on replacing parts in conjunction with the installation of BE bearings and ARP bolts (BE spec'd)? So far I have:

- Oil, filter and drain plug
- Motor mounts
- Oil pan gasket
- Assembly lube (is this provided by BE when purchasing the bearings/bolts directly, if not is there a specific lube?)
- Other seals or fittings (I have heard from shops they replace oil line/oil return line seals, etc.)

Thanks!

[douglee25]

If you have extra coin, it's the right time to install an actual dipstick!

[MPower7]

Originally Posted by noremaC

What is the recommendation on replacing parts in conjunction with the installation of BE bearings and ARP bolts (BE spec'd)? So far I have:

- Oil, filter and drain plug
- Motor mounts
- Oil pan gasket
- Assembly lube (is this provided by BE when purchasing the bearings/bolts directly, if not is there a specific lube?)
- Other seals or fittings (I have heard from shops they replace oil line/oil return line seals, etc.)

Thanks!

This is what I went with:

BE Bearings
ARP BE-Custom Rod Bolts
11137841085 - engine oil pan gasket
11417839832 - pickup tube o-ring
11417839833 - pickup tube o-ring
11417838534 - suction pipe gasket
11427837997 - oil filter kit (oil filter, o-rings, crush washers)
07119904550 x 2 - oil pan drain plug (includes crush washer also)
07-12-9-905-537 - 16 x oil pan bolts
07-12-9-905-599 - 12 x oil pan bolts
07-12-9-905-600 - 2 x oil pan bolts
11812283798 x 2 - engine mounts (optional but a good time to replace if you haven't)
07119904025 x 4 - engine mount nuts (optional but a good time to replace if you haven't)

[noremaC]

Originally Posted by MPower7

This is what I went with:

BE Bearings
ARP BE-Custom Rod Bolts
11137841085 - engine oil pan gasket
11417839832 - pickup tube o-ring
11417839833 - pickup tube o-ring
11417838534 - suction pipe gasket
11427837997 - oil filter kit (oil filter, o-rings, crush washers)
07119904550 x 2 - oil pan drain plug (includes crush washer also)
07-12-9-905-537 - 16 x oil pan bolts
07-12-9-905-599 - 12 x oil pan bolts
07-12-9-905-600 - 2 x oil pan bolts
11812283798 x 2 - engine mounts (optional but a good time to replace if you haven't)
07119904025 x 4 - engine mount nuts (optional but a good time to replace if you haven't)

Great! Thank you.

I went through and created list from Amazon, ECS Tuning and FCPEuro, with Liqui-Moly 10w60, minus the BE bolts and bearings, the total came out to:

$325.95 shipped

PLUS approx $900 for the bolts and bearings

$1,225.95 for parts. $1,200 for labor.

Grand total $2,425.95

Another question here - is the replacement of oil pan bolts a requirement? I'd think unless threads are stripped, they could be reused. Just a thought.

[AutoTalent]

Originally Posted by noremaC

Great! Thank you.

I went through and created list from Amazon, ECS Tuning and FCPEuro, with Liqui-Moly 10w60, minus the BE bolts and bearings, the total came out to:

$325.95 shipped

PLUS approx $900 for the bolts and bearings

$1,225.95 for parts. $1,200 for labor.

Grand total $2,425.95

Another question here - is the replacement of oil pan bolts a requirement? I'd think unless threads are stripped, they could be reused. Just a thought.

You want new ones. Heads up for everyone that these bearings have an end of March ETA at the moment.

[admranger]

Originally Posted by AutoTalent

You want new ones. Heads up for everyone that these bearings have an end of March ETA at the moment.

Not sure you really do as they aren't stretch to yield bolts AFAIK. I didn't replace them on the 3 bearing replacements that I did.

FWIW, I had a couple extras of each length as it's somewhat easy to bugger the heads up if you're not careful (especially if you are using power tools...).

The DIY thread that SYT_Shadow did has all the info you'll likely need, noremaC.

[CHE///MIST3]

Very impressive set-up for providing actual data! I have a question as i'm still trying to take all this in...

A 3 psi drop in oil pressure certainly isn't concerning, but if there was a substantial increase in oil flow due to the increased clearance of the BE rod bearings, what happens to the oil flow across the mains bearings ? Perhaps the data logging captures only total pressure and flow readings via the pump, or there is a way to deduce what happens at the rod vs main bearings?

GM

[Scharbag]

Volumetric flow is proportional to the pressure drop across a system element (yes, this is highly oversimplifying reality but it is a true statement). Just like in electric circuits where voltage (pressure) and current (flow) are linearly related.

Therefore, a 3% drop in system pressure should result in ~3% drop in flow across each element. In simplistic terms, the main bearings and rod bearings can be considered parallel flow elements operating at a common system pressure. The oil flowing through the rotating assembly can either escape through the main bearings or continue to, and escape through, the rod bearings.

Changing the rod bearing clearance changes the rod bearing system resistance. It does not change the main bearing system resistance (yes, electrical engineer here so I am likely mixing terms...). If the oil pump was not pressure compensating, then you would expect a significant system pressure reduction. This is not the case. The S65 oil pump is variable and maintains close to original system pressures even when flow is much higher. Now, if you spin a rod bearing and introduce a very low system resistance flow path, then all of the oil will flow through that path (path of least resistance) and the pump's system pressure will drop (physics is a bitch), causing other damage to occur.

An additional bonus of higher nominal rod bearing oil flow is that ALL of the additional oil that passes through the rod bearings also has to first pass through the main crank journals. This has the benefit of additional crank and main bearing cooling.

I am sure much smarter mechanical people than myself can offer a much more thorough answer. In the end, the small reduction in system pressure is well worth the increased flow.

Cheers,

[CHE///MIST3]

Originally Posted by Scharbag

If the oil pump was not pressure compensating, then you would expect a significant system pressure reduction. This is not the case. The S65 oil pump is variable and maintains close to original system pressures even when flow is much higher.

This part, about the variable pressure pump, helps me to understand a steady flow through the mains as the flow increases through the conrods.

Thanks for taking the time!

GM

[Scharbag]

Originally Posted by CHE///MIST3

This part, about the variable pressure pump, helps me to understand a steady flow through the mains as the flow increases through the conrods.

Thanks for taking the time!

GM

Yup, without a good variable oil pump, things would be different.

Cheers,

[Helmsman]

Originally Posted by CHE///MIST3

This part, about the variable pressure pump, helps me to understand a steady flow through the mains as the flow increases through the conrods.

Thanks for taking the time!

GM

Ha, you're not let of the hook that easy mate!

System oil pressure is one thing and what BE (of natural reasons) have been able to measure. What keeps the bearing from the crank is however the oil layer/pressure over the bearing surface, here we're btw talking about thousands of psi pressure.
Like Scharbag I'm a poor electro guy so this is getting complicated for me but basically there is an optimal oil film thickness in order to maintain an even layer and pressure, which is changed with changed bearing clearance. I leave this in your hands for happy home studies : http://kingbearings.com/wp-content/u...ofessional.pdf

Ps. BTW riding with increased clearance myself since last Summer, and hoping for the best..

[CHE///MIST3]

Originally Posted by Helmsman

Ha, you're not let of the hook that easy mate!

System oil pressure is one thing and what BE (of natural reasons) have been able to measure. What keeps the bearing from the crank is however the oil layer/pressure over the bearing surface, here we're btw talking about thousands of psi pressure.
Like Scharbag I'm a poor electro guy so this is getting complicated for me but basically there is an optimal oil film thickness in order to maintain an even layer and pressure, which is changed with changed bearing clearance. I leave this in your hands for happy home studies : http://kingbearings.com/wp-content/u...ofessional.pdf

Ps. BTW riding with increased clearance myself since last Summer, and hoping for the best..

A few engineers on this thread! ….and yes, that is a great article by King Bearings. Well, I’m a chemist, so while I may not have the physics of flow and pressure as well-engrained I do thrive on the fact that there are many exceptions to the rule, and that sometimes things just WORK, even when not expected to.
I may get flamed for this, but I just don’t think BMW made a mistake, I believe it was a choice….. for all the surviving S65 engines (the vast majority of them) screaming at 8K RPM on a racetrack and then valet parking for a fancy dinner that same evening, it has worked out quite alright. Perhaps BMW tried opening up the clearances in the development of the S65 and found that manufacturing tolerances in the high end, would result in loss of power and smoothness (maybe some engine builders can chime in on this thought) on the flip side, manufacturing to very tight tolerances has led to the destruction of hundreds of engines, that’s the very unfortunate blood price being paid for the remaining “good” engines.
The bearings pretty much all wear prematurely, though, we’ve all seen the photos on these threads for years….most lasting through the warranty period, but after that, the engine, and its components become a maintenance item. That being said, I would want a replacement con rod bearing set as close to the nominal MEASURED original clearance that have been seen in these engines, with the same tri-layer composition, like BE (and ACL?) do…and replace them every 60-80K miles. For those running the increased clearance BE bearings I bet they will work out great as well, long term, but we have yet to see if there are any unforseen effects! I’m just thinking out loud, there are folks who know far more and are actively working towards the best solution aside from a complete engine teardown and rebuild by hand. This is, by far, the most pestering topic for this amazing M3 platform, lol.

GM

[Scharbag]

Originally Posted by CHE///MIST3

A few engineers on this thread! ….and yes, that is a great article by King Bearings. Well, I’m a chemist, so while I may not have the physics of flow and pressure as well-engrained I do thrive on the fact that there are many exceptions to the rule, and that sometimes things just WORK, even when not expected to.
I may get flamed for this, but I just don’t think BMW made a mistake, I believe it was a choice….. for all the surviving S65 engines (the vast majority of them) screaming at 8K RPM on a racetrack and then valet parking for a fancy dinner that same evening, it has worked out quite alright. Perhaps BMW tried opening up the clearances in the development of the S65 and found that manufacturing tolerances in the high end, would result in loss of power and smoothness (maybe some engine builders can chime in on this thought) on the flip side, manufacturing to very tight tolerances has led to the destruction of hundreds of engines, that’s the very unfortunate blood price being paid for the remaining “good” engines.
The bearings pretty much all wear prematurely, though, we’ve all seen the photos on these threads for years….most lasting through the warranty period, but after that, the engine, and its components become a maintenance item. That being said, I would want a replacement con rod bearing set as close to the nominal MEASURED original clearance that have been seen in these engines, with the same tri-layer composition, like BE (and ACL?) do…and replace them every 60-80K miles. For those running the increased clearance BE bearings I bet they will work out great as well, long term, but we have yet to see if there are any unforseen effects! I’m just thinking out loud, there are folks who know far more and are actively working towards the best solution aside from a complete engine teardown and rebuild by hand. This is, by far, the most pestering topic for this amazing M3 platform, lol.

GM

Bearings are not a replacement item in a passenger car. And yes, the S65B40 is a passenger car engine. A really high performance passenger car engine for sure, but still just a passenger car engine. The S65B40 is not a purpose built race engine, where every last HP is extracted by reducing clearances and engineering safety factors to wring every last shred of power out of it. There are many examples of such naturally aspirated high revving engines used in passenger cars:

Porsche GT3 (118HP/L)
Honda S2000 AP1 (118HP/L)
Acura Integra Type-R (108HP/L)
Acura RSX (100HP/L)
Audi R8 V10 (119HP/L) - very high piston speed!!
Ferrari 430 (112HP/L)
BMW M3 (104HP/L) <-- reference

Of these engines, only the S65 seems to have a significant penchant for spinning rod bearings and daylighting engine blocks. BMW chose to specify a tight bearing clearance. Then they chose to use a heavy oil. From the information I have gathered, this is bass ackwards. Tight clearance should have light oil. Finally, and this is the kicker, BMW allowed a manufacturing tolerance range on the rods, bearings and cranks that will, at times, produce a VERY tight engine. Conversely, at times, the tolerance stack will produce a loose engine. But, even if you are lucky enough to have a loose engine, the rod bearing clearance is well below that recommended by King, ACL and Clevite for a high performance, high RPM engine.

There is so much great data in this thread, and others, that explains the issue as well as how extra rod bearing clearance resolves this one item. As for adverse effects, that has also been discussed in detail. Flow is more critical than system pressure. I will take a slight drop in pressure to double the flow any day.

Cheers,

[Helmsman]

Originally Posted by CHE///MIST3

A few engineers on this thread! ….and yes, that is a great article by King Bearings. Well, I’m a chemist, so while I may not have the physics of flow and pressure as well-engrained I do thrive on the fact that there are many exceptions to the rule, and that sometimes things just WORK, even when not expected to.
I may get flamed for this, but I just don’t think BMW made a mistake, I believe it was a choice….. for all the surviving S65 engines (the vast majority of them) screaming at 8K RPM on a racetrack and then valet parking for a fancy dinner that same evening, it has worked out quite alright. Perhaps BMW tried opening up the clearances in the development of the S65 and found that manufacturing tolerances in the high end, would result in loss of power and smoothness (maybe some engine builders can chime in on this thought) on the flip side, manufacturing to very tight tolerances has led to the destruction of hundreds of engines, that’s the very unfortunate blood price being paid for the remaining “good” engines.
The bearings pretty much all wear prematurely, though, we’ve all seen the photos on these threads for years….most lasting through the warranty period, but after that, the engine, and its components become a maintenance item. That being said, I would want a replacement con rod bearing set as close to the nominal MEASURED original clearance that have been seen in these engines, with the same tri-layer composition, like BE (and ACL?) do…and replace them every 60-80K miles. For those running the increased clearance BE bearings I bet they will work out great as well, long term, but we have yet to see if there are any unforseen effects! I’m just thinking out loud, there are folks who know far more and are actively working towards the best solution aside from a complete engine teardown and rebuild by hand. This is, by far, the most pestering topic for this amazing M3 platform, lol.

GM

Agree, surely it must have been a design decision by BMW. The Min clearance (according to recently released/suggested numbers: https://www.m3post.com/forums/showthread.php?t=1614693) are certainly becoming extremely tight, if these should be true in reality its surprising that we don’t see more blow ups. However looking at peoples measured clearance when replacing with OEM shells they typically seem to end up around 0.035-0.04mm.

Far from an engine builder so a complete guess is that the engine is built by ///M for just that, Motor sport. I.e. extensive track use at high rev and load. This doesn’t necessarily fit well with BMWs standard user and service suggestions (i.e. oil/15k mile, 6k rpm from cold..). For the way us normal Joe’s are using the car with short-isch commute, plenty cold starts, only occassional re lines and more selldom if any bearing “services”, I believe a bit more clearance comes handy.

[Assimilator1]

AutoTalent
Are you still able to edit the op & the BE wiki?
The reason I ask is because of this statement following the cold start graphs :-

Summary
These graphs show both BE Bearing and BMW Factory bearings (as lighter colors). It's very clear from these graphs, that the oil pressure comes up faster with BE Bearings than BMW Factory bearings. Having oil pressure come up faster and lubricating the bearings is a huge benefit to reduce bearing wear and increase bearing longevity. This was an unexpected surprise that we didn't anticipate. The graphs also show no decrease in oil pressure over factory bearings. This should allay fears that increased clearance would decrease oil pressure, especially during this critical "Cold Start" time period.

The highlighted part of the text isn't correct for the 30-40C graph which clearly shows a 7-8 PSI drop in pressure, I'm not saying the drop is a problem, but the text jars with that graph.
Actually, that graph is odd, it's showing slightly reduced oil flow too, was the oil cooler thermostat interfering with flow readings?
On that note, I'm curious as to why the pressure drop is a little more at that temperature compared to others?

Also in the 60-80C graph the line for the OEM bearings is missing. Am I right in thinking the data for that was messed up by throttle inputs? I think you mentioned that somewhere in this thread (and in the op Those graphs contained too much throttle input, and we think that contaminates the results. Now that we know this, we will see if we can filter out the results containing too much throttle, and moving forward will capture results without any throttle until 30-seconds has passed since starting the engine.), but theirs no mention of an update in the op here or the bearing wiki?

Some of this may have been observed during hard cornering (more on that later)
I don't recall seeing that follow up, have I missed it somewhere?

Regardless of the above, that's an amazing amount of effort, work & money you've put into it. I Googled the oil flow sensor you used, & although I couldn't find a price for that one, I did come across a larger used one on ebay & even that was crazy expensive!
So thanks for your time & effort & sharing the extensive data