Pictures of Replaced Rod Bearings

[StripclubDJ]

Originally Posted by MaximusB

I have a 2001 celica with 160,000km on it. 60,000km was on a stock motor, and in stock form the motor redlines at 8400rpm. When the motor was pulled and disassembled the bearings were in mint condition, zero wear. I put in a built motor with a turbo and 8800rpm redline. 100,000km later the bearings were pulled because I had to replace the oil pan and they had zero wear on them as well.

So I don't buy the idea that bearing wear is normal on a high revving engine. Also I don't, and never will, believe that bearings are wear and tear item. If they have the proper clearance and oil flow then they should last as long as the motor.

I was always curious as to how WPC bearings will hold up over time since their coating actually adds thickness and the clearance is even worse than OEM.

False bud

The "coating" is not a layer added
It's a tiny layer takin away

It's a shot peening strengthening process

[MaximusB]

Guess I’m wrong then.

[Scharbag]

http://www.wpctreatment.com/faq.htm

WPC treatment is an interesting process.

[pbonsalb]

I put wpc treated stock bearings in my 08M3 in 2014 but have added only 35k miles since and am not ready to replace them preventatively again.

One member pulled a set with a fair amount of miles and they looked good. Another pulled a set from an S85 after relatively few miles and they looked bad.

It will be awhile before we have a number of examples to go on, and that is true for all the options for replaced bearings

[Spoolin1]

Originally Posted by MaximusB

I was always curious as to how WPC bearings will hold up over time since their coating actually adds thickness and the clearance is even worse than OEM.

I believe that "coating" helps suspend the oil film as one benefit possibly, thus reducing wear, but is not a true fix to the issue. I also believe BMW screwed up with the oil passages to the rod and even main bearings on this engine. That is probably where things need to be addressed to resolve the issue for a long term fix.

[Scharbag]

Originally Posted by Spoolin1

I believe that "coating" helps suspend the oil film as one benefit possibly, thus reducing wear, but is not a true fix to the issue. I also believe BMW screwed up with the oil passages to the rod and even main bearings on this engine. That is probably where things need to be addressed to resolve the issue for a long term fix.

There is a good thread about the clearance issues with the S65 engine. BMW chose to specify very tight clearances for a high revving engine. This includes very tight rod side clearances. Best practice demands ~0.001" clearance for each 1" of bearing journal diameter. Even on the loose end, the rod bearing clearance is less than this from factory. On the tight end, with bad tolerance stacking, the rod bearings are just way to tight.

There is oil flow data that supports the thesis that low oil flow at high rpm is causing premature bearing wear. There is also data that supports the thesis that proper bearing tolerance elevates this low flow problem and should eliminate the rod bearing wear. Hopefully some high mileage BE bearings will be pulled that validates this thesis. There is one example I have seen in the oil thread that shows used BE bearings that look like hydrodynamic bearings should.

Not a lot can be done for the mains without an engine out experience. That said, it seems that there are far fewer main failures than rod failures. Fingers crossed.

Cheers,

[MaximusB]

I looked up the measurement of WPC vs stock. The added clearance is almost negligible according to bearing wiki.

[pbonsalb]

WPC treatment is not to increase gap but to reduce friction and add strength.

[Spoolin1]

Originally Posted by Scharbag

There is a good thread about the clearance issues with the S65 engine. BMW chose to specify very tight clearances for a high revving engine. This includes very tight rod side clearances. Best practice demands ~0.001" clearance for each 1" of bearing journal diameter. Even on the loose end, the rod bearing clearance is less than this from factory. On the tight end, with bad tolerance stacking, the rod bearings are just way to tight.

There is oil flow data that supports the thesis that low oil flow at high rpm is causing premature bearing wear. There is also data that supports the thesis that proper bearing tolerance elevates this low flow problem and should eliminate the rod bearing wear. Hopefully some high mileage BE bearings will be pulled that validates this thesis. There is one example I have seen in the oil thread that shows used BE bearings that look like hydrodynamic bearings should.

Not a lot can be done for the mains without an engine out experience. That said, it seems that there are far fewer main failures than rod failures. Fingers crossed.

Cheer,

I can't remember the exact size of the journals, but Honda OE rod bearing spec tolerances on the high revving F20c in the S2000 range from .0012-.0021. There has been literally zero issues that I am aware of on this engine, so it stands to believe that BMW did a disservice in such tight tolerances, which seems to compound in the stack up if everything is on the tight end, causing what sounds like inadequate oil film.

[Scharbag]

Originally Posted by Spoolin1

I can't remember the exact size of the journals, but Honda OE rod bearing spec tolerances on the high revving F20c in the S2000 range from .0012-.0021. There has been literally zero issues that I am aware of on this engine, so it stands to believe that BMW did a disservice in such tight tolerances, which seems to compound in the stack up if everything is on the tight end, causing what sounds like inadequate oil film.

It looks like The F20C has 1.8888" to 1.8898" rod journals (The Japanese love precision). Utilizing Clevite/King/ACL best practice recommendations of ~ 0.001"/", the rod bearing clearance should be ~ 0.00189". Given Honda's allowable clearance range, the F20C has:

min = 0.000635"/"
nominal = 0.000873"/" (assuming normal distribution)
max = 0.00111"/"
sevice limit = 0.00127"/"

I am a bit surprised as to how relatively tight the F20C engine is. Still, it is not as tight as some S65s...

For the factory S65, going by the data gathered by BE, the "/" values are:

088/089 min = 0.00029"/" (YIKES - this is TOIGHT)
088/089 nominal = 0.00073"/"
088/089 max = 0.00103"/" (even if the stars align, barely meets best practice)

702/703 min = 0.00056"/"
702/703 nominal = 0.00073"/"
702/703 max = 0.00098"/"

Honda specifies the use of 10W30 for the F20C engine with relatively tight nominal clearances. BMW specifies 10W60 for the S65 engine with very tight nominal tolerances. Let us not even discuss the minimum 088/089 bearing clearance as it is ridiculously tight.

My take on this is that BMW did the following:

1) designed an engine with very tight oil clearances (and we have not even started to discuss side clearances)
2) allowed too much variance in rod/crank/bearing sizes (especially with the 088/089 bearing shells) without offering a choice of rod bearing shell thicknesses

The combination of these 2 poor choices can create a situation where grossly inadequate clearances are present for a high revving engine.

Thankfully, BE used the data they collected to design a new, properly sized bearing shell, that allows for the following clearance ratios:

min = 0.00088"/" (minimum is still better than factory nominal)
nominal = 0.00115"/" (spot on what Clevite recommends)
max = 0.00137"/" (a little loose but still acceptable)

I know this has all been beaten to death but it is Sunday and I had some free time. I agree, there are many high revving engines out there that do not have bearing issues. BMW screwed up both the S85 and S65. At least the rods can be fixed. The mains, that is a much bigger task...

The mains have the following clearance ratios:

min: 0.000508"/"
nominal: 0.000678"/"
max: 0.000847"/"

The above is based on measurements from BE. Thankfully, there are different sizes of main shells for the S65 and S85. This leads me to hope that there is a better chance the factory avoided assembling an engine with unreasonably tight main bearing clearances. Perhaps someone more thoroughly versed in the S65 and S85 engines could comment on the main bearing clearance issue.

Anywhoo, I reeeeeaaaaaly hope my S65 lasts a long time. It is such a fun car!!

Cheers,

[Spoolin1]

Wow, those are some tight clearances on the S65 for sure. Good write-up man.

Just so you are aware, I held the record for highest hp S2k on the stock block at over 800 whp (~1000 crank hp). The car ran boosted like this for a good 12k miles, ranging from 300whp to over 800 before I decided to pull it and have it built for even bigger power. When Allen from InlinePro disassembled the engine, the bearings were all in excellent condition and I revved it to 9600 rpm. Even though the F20c has relatively tight bearing clearances, it still shows Honda knew their sh** with oil distribution.