Understanding of bearing metalurgy in different engines

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Even if you do not run analysis on your engine I believe it is important to understand that the difference in the metalurgy of the rod and main bearing from engine to engine is yet another one of the variables that seems to make some of these engine analysis's here so different from one another . The current trend from the auto makers is the new Bi-Metal "primarily" Aluminum rod and main bearings . These bearings use less to no lead in the metalurgic make-up . When you see a Dodge 4.7 throw out little to no copper/bronze in an analysis yet the 4.7 HO Dodge engine does this Bearings used might help explain . The HO engine uses the tried and true Tri-metal bearing most commonly used in hi-performance engines . In the past these offered better embedibility but times have changed . More on bearing material trends http://www.aera.org/Members/EngineTech/edge1196/page3.htm Geeze, might be an ill fated attempt here , brower lost more links and out of time to post however [Smile] something to ponder when you see a Ford analysis with ZERO lead and 5w-20 wt oil used is that do you know the exact makeup and percent of lead in the bearings ? Are these engines typically throwing out higher aluminum than a tri-metal bearing engine and making that 5w-20 look really good to those looking at lead as the primary metal of the rod bearing ? Try a google search and see what comes up . Some engines are now using the Bi metal bearings on the rods and all the mains except the thrust bearing which in this case the old trimetal bearing is used .....all the ducks are not in a row there . Try googling and many pro written articles on tri-metal and bi-metal bearings will come up . This info might help understand the differences in UOA's but the links I lost made for an ill fated attempt as I had more to say [Frown] but to those interested it might plant the seed needed to produce the need for more info on their engine and bearing type used to aid in decoding your engine oil analysis and possibly even wt of oil used [Eek!] [ April 30, 2004, 05:36 AM: Message edited by: Motorbike ]
 
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Excellent points. Which sort of goes back to the need for trending the UOA over time in any engine to see what is happening, each engines wears differently even if it came off the line back to back with another. Manufacturer to manufacturer is pretty difficult, what is important is your engine mapped over time to see the trend.
 
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Motorbike...you took the words right out of my thoughts...just didn't know how to put it to paper without any references and then risk getting slammed by some of the members here. But, that was what I was wanting to get at....are these engines showing low wear with a "thinner" oil actually using different types of metal? I have always thought that just because Pb and Cu is showing up low on some of these Ford V8's, doesn't necessarily mean that there is no wear. It has to be showing up in different metals that the labs are testing. I will never let go of the belief that a thinner oil has no place for a long lasting engine. I've been reading other posts here that are starting to come around too. Just wait....we'll all see the light soon.
 
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Thanks Motorbike. Good points. Only problem, I've never been able to find actual bearing alloy composition for any of my cars. Maybe I'm just a bad googler? Actually Schmoe, the article supports the trend to thinner oils, as the new bi-metal Enginetech bearings discussed require less than half the MOFT of older bearing designs.
 
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I find it curious that this thread didn't get a lot more traffic from all the "expert" UOA analyzers we have here at BITOG. [Big Grin]
 

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Originally posted by Jason Troxell: ...I've never been able to find actual bearing alloy composition for any of my cars....
I've analyzed bearings in the lab in a lot of detail. Your standard journal bearing in an automotive engine is basically pure copper powder on a steel backing that is sintered to fuse the copper particles. This porous copper is then infiltrated with lead and the whole piece is electrocoated with a thin layer of tin. I've seen another design where an aluminum alloy layer is bonded to a steel backing. This aluminum has around 12% silicon in the form of small particles in the aluminum matrix. I'm not too crazy about using aluminum as a bearing material because of the galling issues. I've also heard rumours of some premium engines (Cadillac?) that use silver in the bearing.
 
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quote:
Originally posted by Kestas: I've seen another design where an aluminum alloy layer is bonded to a steel backing. This aluminum has around 12% silicon in the form of small particles in the aluminum matrix. I'm not too crazy about using aluminum as a bearing material because of the galling issues.
My understanding is that Ford has used this type of bearing in their "modular" engines for quite some time now. Are you aware of any other manufacturer that use this type of bearing?
 
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427Z06, Thanks for that link, interesting reading. Back to the tri-metal, bi-metal thing, maybe in the future tri-metal bearings might be an optional extra, like metallic paint. "Would you like tri-metal bearings for an extra $1,000, sir?" [Big Grin] From info on the above site, it appears that bi- metal bearings have half the life of a good tri-metal bearing. Off course, if the engine doesn't last too long, they sell more of them, right? God bless the bean counters. Dave [ May 04, 2004, 02:37 PM: Message edited by: DavoNF ]
 

Kestas

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Originally posted by 427Z06: My understanding is that Ford has used this type of bearing in their "modular" engines for quite some time now. Are you aware of any other manufacturer that use this type of bearing?
It is at Ford that I was introduced to the aluminum bearing. They sent all the "problems" to me for documentation. I'm not sure how popular aluminum bearings are across the board with other manufacturers. I imagine aluminum bearing development is a response to the effort of removing ALL lead from plants. What a shame, lead is an excellent solid lubricant, and aluminum is less forgiving when metal to metal contact is made. Aluminum bearings, together with the ferrite cap problem inherent in ductile iron journal surfaces makes for a bad combination. No amount of synthetic oil can help you there.
 

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quote:
Originally posted by Schmoe: ...But, that was what I was wanting to get at....are these engines showing low wear with a "thinner" oil actually using different types of metal?...
This is why trending is important. In my Acura RSX, for example, I have reports going back to the factory fill and I could see the wear metals, including lead, trend downward as the engine wore in. So lead is in the bearings--and according to my UOAs on 20-weight--that's where the lead is staying.
 
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quote:
Originally posted by Jay: This is why trending is important. In my Acura RSX, for example, I have reports going back to the factory fill and I could see the wear metals, including lead, trend downward as the engine wore in. So lead is in the bearings--and according to my UOAs on 20-weight--that's where the lead is staying.
Do you know this for sure? What if only the crank thrust and few other key points use bearings made of the Lead-Tin/Copper-Lead combo? You might see a little lead from these and you would see them trend down over time too. Besides, just what is the acuracy/precision of lead levels in UOAs?
 

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Quote: " I've seen another design where an aluminum alloy layer is bonded to a steel backing. This aluminum has around 12% silicon in the form of small particles in the aluminum matrix. I'm not too crazy about using aluminum as a bearing material because of the galling issues. Is it the Mazda 6 engine that is throwing out Si and Al in analysis ? They also use hyperuetectic pistons so it would be very difficult if not impossible to tell how the engine bearings were wearing through analysis if they also used this type bearing . Which full circle makes me ask .... what about all the leadless Ford UOA's with 20wt and the Ford engines with low miles that are supposed to be leaching Si from the gaskets per some posts in that section . One Ford in particular I'll try to find has huge aluminum and Si content Here is a 4.7 Dodge with 0 lead in 6k miles , per the link I posted this engine uses the newer style Bi-metal bearings . http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=001175#000000 Look at the Tri-metal bearings in the 5.9 Dodge http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=001032 [ May 04, 2004, 06:30 PM: Message edited by: Motorbike ]
 
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quote:
Originally posted by Motorbike: Is it the Mazda 6 engine that is throwing out Si and Al in analysis ?
Reviewing Jays UOAs, I'd say it correlates well with the Aluminum bearing theory. Initially low lead numbers when new, quickly going to 0-1 ppm, at the same time you see elevated Al, Si during it's break in period. Of course this is all theory at this point. It sure be nice to know what bearing materials are used in Mazda I4s & V6s and Honda/Acura 4 cyls. Most of what I can find on the web says that Ford is using Aluminum bearings in most of it's modular engines.
 
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Hello, We had a simalar discussion a year or so ago in the metal of another thread. I used Lexus and Toyota V8's as an example. They use aluminum and cadnium in their bearings more so then lead, copper and tin. With this said we do not see a spike in any of these materials either. When you look at the fact that the Lexus block and heads are all aluminum it is no small wounder.The Toyota V8 has a cast iron block but everyting else that is cast is aluminum. To my limited knoldge of modern Toyota engines very few use servicable aluminum/cadnium bearings! Most are still the trimetal/babitt style with bronze thrust washers/bearing. While alloys definately make a difference in a bearings charteristics I think that other things are more important. The other more important factors are stiff lower end, good oil control, high volume and pressure of oil, reduced tolerance stacking, good emissions control and excellent quality control.
 
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Thanks for your input JohnBrowning. It very well may be that a very stout bottom end will show very little lead in the UOAs no what the bearing material. Although, I somehow still have a hard time believing that only 0-1 ppm lead in UOAs after 6-7K of very hard driven miles can be fully explained by what you mention above. Maybe you'll have the pleasure of convincing me otherwise. [Smile] Anyway, this discussion is just to see if we can give any credence to the theory that when someone claims that they get 0 lead in the UOA, it therefore "proves" without a shadow of doubt that brand X oil in Visc whatever is the holy grail of oils. In other words, we're just trying to make sure we're comparing apples with apples and oranges with oranges. [Cheers!]
 
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Aren't many bearings layered (Not talking about alloys now)? Meaning the top layer is for example bronze, under it is copper. I have seen picture of crankshaft bearings that were partially worn down to the copper layer. If a car has such bearings, a sudden spike in copper would surely indicate severe bearing damage. [ May 04, 2004, 07:46 PM: Message edited by: moribundman ]
 
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