Z4M S54: Rod bearings replaced again ...

[XMetal]

Originally Posted by JonM

Another data point for S65 engines with regards to oil pressure... the Stack gauge in my M3 reads about 83 psi at steady highway RPMs. It can peak higher than that and even at idle it runs around 45 pounds. Altogether much higher than my S54 engines.

When I installed the gauge, I thought I had done something wrong I was so surprised. I tried other gauges and other senders, all the same result.

Even with the higher oil pressure, don't the S65 suffer similar bearing issues? So...Would boosting pressure (changing oil pump) help our S54?

[JonM]

Originally Posted by XMetal

Even with the higher oil pressure, don't the S65 suffer similar bearing issues? So...Would boosting pressure (changing oil pump) help our S54?

No, the s65 does not suffer from rod bearing failures. At least, not chronically and to no where near the same extent as the s54.

I don't know enough about engines to speculate on correlation between pressure and failure rates. Seems plausible though, but you would think they would have thought of that.

[pal]

Originally Posted by JonM

No, the s65 does not suffer from rod bearing failures. At least, not chronically and to no where near the same extent as the s54.

I don't know enough about engines to speculate on correlation between pressure and failure rates. Seems plausible though, but you would think they would have thought of that.

Actually, that is not true. A tracked S65 is not only wearing out the rod bearings but also the mains. I was contemplating an S65 swap down the line until RRT informed me of two ventilated blocks on S65s due to rod bearing failures. The bearings on that motor are tiny as well and it revs even higher.

[Finnegan]

You'd think the smart folks at BMW would learn from past mistakes. Any word on whether street use of the S65 suffers the same ills?

[pal]

Originally Posted by Finnegan

Any word on whether street use of the S65 suffers the same ills?

Here is a VAC post along with a 24K mile rod bearing image
http://www.m3post.com/forums/showthread.php?t=824004

There is also a thread of an S65 owner with 100K street miles and I think one or two paris of his bearings were down to the copper (I think) layer.

http://www.m3post.com/forums/showthread.php?t=880264

Originally Posted by Finnegan

You'd think the smart folks at BMW would learn from past mistakes.

They have and hence switched to turbo motors that rev a lot lower. They of course have their own set of problems with carbon build up on valves, valvetronic noises, fuel pumps etc. I think high performance and strained engines just have weak points which get exposed sooner when regularly driven to their limits and beyond.

[Finnegan]

Wow. Good research!

Always trade offs with anything, right?

[RobertRO]

Just to tease you a bit, here's how a rod bearing looks like in an allegedly poorly maintained BMW M70 engine (first generation of V12 used on E32 7er and E31 8er), after 170,000 miles (~270,000 Km):



Nothing can beat the endurance of a low rev, low stress (300 HP out of 5,000 ccm) n/a gasoline engine

Source:
http://bmwe32.masscom.net/sean750/en...0rebuild_3.htm
(scroll down about 1/3 of the page)

[thekurgan]

Originally Posted by pal

Actually, that is not true. A tracked S65 is not only wearing out the rod bearings but also the mains. I was contemplating an S65 swap down the line until RRT informed me of two ventilated blocks on S65s due to rod bearing failures. The bearings on that motor are tiny as well and it revs even higher.

I've only seen supercharged main bearings as an issue, and those are few and far between actual numbers. My indy made mention of a bedplate issue during production; but he's yet to have to perform any re-torquing of it. Even the rod bearings wearing, seems very few with an issue and if the S54/S65 go to 100k without significant wear, these would truly be marvels of engines. I'm also still very skeptical of the oil specified for street driven vehicles that don't see enough time to get the oil to 220+. I'm thinking of trying a 3k mile run of 0w-40 from Mobil 1 as we are approaching colder weather and my oil never gets to 210 by the time I arrive at my gym or office.

[thekurgan]

Originally Posted by RobertRO

Just to tease you a bit, here's how a rod bearing looks like in an allegedly poorly maintained BMW M70 engine (first generation of V12 used on E32 7er and E31 8er), after 170,000 miles (~270,000 Km):



Nothing can beat the endurance of a low rev, low stress (300 HP out of 5,000 ccm) n/a gasoline engine

Source:
http://bmwe32.masscom.net/sean750/en...0rebuild_3.htm
(scroll down about 1/3 of the page)

Yes, but the 7 is an entirely different maintenance nightmare on its own.

[GuidoK]

Originally Posted by pal

My strategy is to replace rod bearings again and possibly rebuild the bottom end with Pauter or Carillo rods and new OEM pistons and rings on OE crank and bearings.

Do Carillo or Pauter rods also have cracked/broken big end caps (like the bmw rods)?

What I mean is: why go with aftermarket rods? Do you need extra lightweight rods or do you think the bmw rods are not strong enough?

Originally Posted by Finnegan

You'd think the smart folks at BMW would learn from past mistakes. Any word on whether street use of the S65 suffers the same ills?

critical rod bearings is a flaw of which a lot of high revving engines suffer. Especially if they have a long stroke like the s54 (long stroke means higher force on the bearings). The s65 and s85 have shorter stroke but are still not problem free (although less critical than the s50/s54). Also piston weight and power output is a factor. Also with high revs there is risk of cavitation erosion in the bearings. I think that that is a major factor in the s54 design judging from a lot of wear marks I sometimes see on the bearings (cavitation erosion gives typical round/oval wear spots).
Maybe you can influence cavitation erosion with oil pressure and oil thickness. I don't know.
Some bearing surfaces are more sensitive to cavitation erosion than others.
But I've also seen pictures of s85 bearings with typical round/oval wear spots.

[pal]

Originally Posted by GuidoK

Do Carillo or Pauter rods also have cracked/broken big end caps (like the bmw rods)?

What I mean is: why go with aftermarket rods? Do you need extra lightweight rods or do you think the bmw rods are not strong enough?

I don't believe they are cracked like BMW rods. Cracked rod manufacture is probably an expensive operation and besides OE and high end tuning houses most places won't have the budget for it.

That being said, the reason to consider Pauter/Carillo is because they are lighter and possibly allow me to use a lighter aftermarket piston as well. And partly because a reputed racing shop like RRT says they have had good results building motors with that. And the side effect may be a bit more power from lighter rotating components.

Originally Posted by GuidoK

critical rod bearings is a flaw of which a lot of high revving engines suffer. Especially if they have a long stroke like the s54 (long stroke means higher force on the bearings).

Yes, high revs and long strokes kill bearings. This is evident as my top bearings (that take the most load on power stroke) were worse than the bottom ones.

[XMetal]

Originally Posted by seank

Yes, they can be modified. That is what VAC started doing when the s14 euro pump became NLA. I don't know how to do it and I can't find the write up on s14.net about it. There search bar is worthless. That being said, for $500-$600 i would buy VAC's. They say that it will increase flow by 22% and it should also increase pressure.

These would also be good questions for Andrew Lang. If I need to replace my bearings and/or pump, this is the route that I am going.

Stopped by Lang Racing yesterday for an alignment on my X5 (awesome deal with the yelp discount), and also to check out their shop. Chatted briefly with Andrew on the bearing issue. He doesn't seem to think that it's necessary to swap out/change/modify the CPV when going to a higher pressure/flow pump. Anyway...he will be racing an S54 car at the 25hours of Thunderhill in December. Those of you in NorCal can go see him race his race-built S54 in person!

Since Andrew is having trouble activating his account on here, he asked me to post the following for him:
“Just to respond to some of the comments in this thread, we have some more details and photos on the S54 rod bearing widening kit here: http://store.langracing.com/s54-rod-...-modification/

Also, we have built and shipped engines as far as Korea and the cost isn’t that high. I think Korea was 850 dollars to ship a long block. There is the possibility to ship fully assembled S54’s globally but shipping a modified crankshaft kit really isn’t very expensive. Crankshaft weight is about 50lbs.

Sean also brought up a comparison between the S54 and the S14. Yes the S14 had some rod bearing issues but nowhere near the extent of the S54. When looking at the S54 we see an engine that is built to the limit almost from the factory. We have very little space between the cylinder bores and the stroke (bore 87 mm x stroke 91 mm). The stroke is also relatively for an S54 compared to most BMW engines. The piston velocity on the S54 revving to 8k RPM 4773.33 Ft/min, this is the fourth highest for a production engine. There was nowhere left to go on the 6 cylinder naturally aspirated platform for BMW, hence the V8 in the E90.

What that means to me as an engine builder is we have to take extra precautions when building these engines, particularly for race applications, even more so than when we build S14’s.”

[Finnegan]

^

[RobertRO]

I plan to perform a preventive replacement of the rod bearings on my E86 Z4M, and I understand that ARP rod bolts are reusable, therefore I am considering to use ARP instead of BMW bolts.

I have noticed that VAC Motorsports sells an ARP Rod Bolt Stretch Gauge, which may provide a better preload of the rod bolts, compared to the classic torque wrench:
http://store.vacmotorsports.com/arp-...p1731c229.aspx

If anyone has used the ARP Bolt Stretch Gauge for torquing the S54 rod bolts, I would appreciate a brief review. Is it easy to use and accurate? Do you recommend it over the torque wrench?

[LangRacingDevelopment]

Originally Posted by RobertRO

I plan to perform a preventive replacement of the rod bearings on my E86 Z4M, and I understand that ARP rod bolts are reusable, therefore I am considering to use ARP instead of BMW bolts.

I have noticed that VAC Motorsports sells an ARP Rod Bolt Stretch Gauge, which may provide a better preload of the rod bolts, compared to the classic torque wrench:
http://store.vacmotorsports.com/arp-...p1731c229.aspx

If anyone has used the ARP Bolt Stretch Gauge for torquing the S54 rod bolts, I would appreciate a brief review. Is it easy to use and accurate? Do you recommend it over the torque wrench?

http:// http://www.langracing.com/s54-rod-bearing-and-bolt-replacement-with-arp-fasteners/

Ive done it a few times now. If you want a couple tips give me a call, fairly straight forward job but just a couple tricks that make it a lot easier.

Always use rod stretch whenever possible. That's my primary reason for using arp over oem. Better accuracy. Make sure you measure starting lengths of every bolt and keel that info. Youll need it when you do the bearings in the future to make sure the bolts didn't stretch permanently.

[Swashplate]

I am currently in the middle of this issue. Going with the Bimmerworld kit with the ARP bolts.....and now a Dr. Vanos cryo hub

But that should remedy any and all of the weak spots on this engine.