Understanding of bearing metalurgy in different engines

[MNgopher]

All I can say is that it again shows how difficult it is to get a true comparison between engines without knowing other details. Also highlights the importance of trending analysis, not just picking one point out.

I'm amazed that its taken this long for you all to figure out the low wear out of Ford modular engines in terms of Lead wear- its been pointed out before, but never discussed...

Also points out the folly in trying to say one motor from manufacturer "A" is better than the motor from Manufacturer "B". Fine, one throws out lead, etc... out, and the other doesn't does not inherently mean Engine A is better than B.

 

[427Z06]

quote:

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Originally posted by MNgopher:

I'm amazed that its taken this long for you all to figure out the low wear out of Ford modular engines in terms of Lead wear- its been pointed out before, but never discussed...

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Sorry...I haven't had a chance to read all 698,743 posts. Only been a BITOG member for about 6 months.

 

[labman]

This is interesting. I hope none of you choke at the idea of asking a salesman what kind of bearings the engine in his truck has. I don't think aluminum bearings are an innovation they are going to tout. Lead may make good bearings, but it is not only toxic, but expensive. Nobody would ever use the stuff, if something else worked as good. Note, tin is expensive too. Don't call cheap stuff tinny.

Some years ago, I noticed some small engines having the crank running directly in the aluminum housing.

With aluminum bearings, is flow very important, and NEVER let it run dry?

 

[Motorbike]

Years back a company called Vandervell made aluminum bearings without copper/bronze on the thrust side for the small and BB Chevy's along with other engines .

As I remember, they worked fairly well in a studded 4 bolt block with a steel crank " low deflection " but did have another alloy plated on the thrust sides of unknown type .

So yes , these type bearings are nothing new but are relatively new in comparison to what Detroit has been using for years on the assembly line .

I had read a article about these bearings about three years back and thought GM was going to use them at the time . If lead is a environmental hazard I would suppose it is only matter of time till none of the makers use a composition with it .

[ May 06, 2004, 11:06 AM: Message edited by: Motorbike ]

 

[Whimsey]

Ford actually has some of the specs for their engines in a book available to their sales people and any one who knows to ask for it. In all honesty I found it by just being nosey

. For my 2002 4.6L V-8 it lists the the camshaft bearings as being aluminum and the main bearings as being steel backed aluminum-lead silicon alloy. The connecting rod bearings are also steel backed aluminum-lead silicon alloy. The pistons are hypereutecic aluminum alloy with a graphite skirt coating. The top compression ring is cast iron alloy with a moly plasma filled groove finish. The second compression ring is cast iron with a phosphate coated finish and the oil control ring is steel with oxide coated chrome plated finish. What this means I don't know

. But I do know these engines show little wear period no matter what oil they use. Maybe Ford has done something right. Except for the leaking head gaskets(mikep

) and a few sparkplugs sent into orbit.

Whimsey

[ May 06, 2004, 01:33 PM: Message edited by: Whimsey ]

 

[Kestas]

All old materials technology for an automotive engine except for the graphite skirt coating which has only recently become widely used in production engines.

 

[Whimsey]

quote:

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Originally posted by Kestas:
All old materials technology for an automotive engine except for the graphite skirt coating which has only recently become widely used in production engines.

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May be "old" technology but it seems to work in this engine. Is there an inherent problem with the bearing material used in this engine as compared to bearings that show lead wear?

Whimsey

 

[427Z06]

quote:

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Originally posted by Kestas:
It may be worth mentioning that crank thrust bearings operate differently than journal bearings. Though they don't see the forces journal bearings experience, they aren't able to develop the hydrodynamic film that journals develop during use.

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Good point Kestas. Plus, there are quite a few other bearings in an engine besides the crank and rod bearings, and they may not see the same kind of forces.

 

[JohnnyG]

Where does this leave us with the Cadillac Northstar engine? I understand that the connecting rods are made from a powdered metal, compressed under high pressure and heat to form a solid material with no internal casting stresses. The bearings are machined directly into the caps, no "bearing" is inserted, then the caps drilled and tapped while the rod is still in one piece. The final step is to split or break the caps into two pieces, no machining of the cap surfaces whatsoever, the rough breaks are bolted back together on the crank, which forms a matched, unmovable, nearly solid connection. What metals should I look for to indicate crank bearing wear?

 

[Kestas]

It may be worth mentioning that crank thrust bearings operate differently than journal bearings. Though they don't see the forces journal bearings experience, they aren't able to develop the hydrodynamic film that journals develop during use.

 

[MNgopher]

quote:

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Originally posted by 427Z06:

quote:

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Originally posted by MNgopher:

I'm amazed that its taken this long for you all to figure out the low wear out of Ford modular engines in terms of Lead wear- its been pointed out before, but never discussed...

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Sorry...I haven't had a chance to read all 698,743 posts. Only been a BITOG member for about 6 months.

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Wasn't trying to be sarcastic or mister know it all - just pointing out how some folks always have marveled at 0 lead, been told about the bearing materials, and still not connected the dots... Kind of amusing for a crowd like this to not see the forest through the trees sometimes! And by far this isn't the only case where that hapens!

Nice to see an intelligent discussion about it though!

 

[Kestas]

quote:

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Originally posted by JohnnyG:
Where does this leave us with the Cadillac Northstar engine? I understand that the connecting rods are made from a powdered metal, compressed under high pressure and heat to form a solid material with no internal casting stresses. The bearings are machined directly into the caps, no "bearing" is inserted, then the caps drilled and tapped while the rod is still in one piece. The final step is to split or break the caps into two pieces, no machining of the cap surfaces whatsoever, the rough breaks are bolted back together on the crank, which forms a matched, unmovable, nearly solid connection. What metals should I look for to indicate crank bearing wear?

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I'm intimately familiar with this design. I even had a hand in developing it. My colleague has a patent on this design. It is now used across the board in nearly all Ford engines.

No, the bearing is not machined into the conn rod/cap assembly. The assembly is machined to accept conventional journal bearings. There should be no wear particles coming from the base powdered metal assembly during normal use.

 

[JohnBrowning]

Aluminum bearings tend to flush out debris rather than hold it. Aluminum bearing alloys also contain silicone which helps resist seizure and actually polishes the crank. Aluminum bearings melting point is 3X that of babitt bearing. Copper/lead offers the best combination of strength, surface action and embedability. Copper/lead can carry 12,000 pounds per square inch versus about 7,000 to 8,000 psi for aluminum, it can handle less than perfect conditions, and is a more forgiving material than aluminum in a typical aftermarket application.

Found this on google!

 

[Terry]

Kestas,John Browning this is the kind of stuff we need more of here at BITOG.

To many of those that could impart more experienced science sit on the sidelines and snicker or quibble about joining in here and I for one thank both of you and invite others with this kind of background to pitch in !

Thanks.

TD

[ May 07, 2004, 08:45 PM: Message edited by: Terry ]

 

[JohnnyG]

Thanks Kestas, for clearing up my misconception. Would you please answer the last part of my question, which type of bearing is inserted and what metals should I look for in a UOA?

 

[Last_Z]

The slide show that 427Z06 posted states that during initial start-up, the bearing and the shafts actually come in contact. If so (and I have no reason to doubt them), then the better oils with higher amounts of additives and/or superior base stocks, should in theory provide much better protection through the use of such additives (Zinc, Boron, Moly, Esters) than lower additized oils such as SuperTech and Valvoline?? Is this a correct assumption?

 

[Kestas]

quote:

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Originally posted by JohnnyG:
...which type of bearing is inserted and what metals should I look for in a UOA?

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I don't know which type of journal bearing is presently used in production for the Northstar engine. If it's the aluminum type, you'd be hard pressed to distinguish whether the aluminum and silicon came from the bearing or some other part of the engine such as the piston (Al, Si) or sand (Si, from the intake). If it's the copper type, you'd look for lead. Can't depend on tin because the piston is tin plated for break-in.

John, I'd be more concerned with the ductility and modulus of elasticity than with tensile strengths when comparing material properties for journal bearing application. You brought up an interesting point on embedability of a bearing material. This is all-important for cast ductile iron crankshafts. They have a (potentially) unique journal surface condition called "ferrite caps". It's related to the grinding and polishing on a ductile iron surface (which has microspheres of graphite). I don't want to get too technically heavy on this, but the end result is that sometimes the crank journal surface - if not perfectly ground and lapped at the manufacturing facility - can have micro-flaps of material that can potentially stick up beyond the oil film and clearance thickness and damage the bearing. If light, the bearing can handle a few embedded particles. If really bad, it can wipe out the bearing.

Beyond the crankshaft, another problem is that sometimes the parts aren't washed properly at the manufacturing facility, and the engine is put together with dirt in it. Again, embedability of the bearing is very important.

These problems mentioned above are some of the very issues my clients come to me for analysis. If I may toot my own horn here, I've actually been considered for a position at Federal Mogul to head up development of new journal bearing alloys.

 

[JohnnyG]

Kestas, Thanks for the reply. I'll shoot this back to a GM engineer to see if I can get some current production info.

 

[JohnBrowning]

Terry, I cut and pasted that from different articles. It was quicker then if I had typed it myself and more brief. Fedral Mogal has authored some great papers on bearing composition but they are SAE papers. I read one last year that was 28 pages of incredable information. I wish I could copy them at work and bring them here but that would be like stealing. If I can find the numbers for the SAE articles I will share the article numbers. I will only share the meaty ones because they cost money to buy. I have access to every single SAE paper but I do not think it would be right to use them for non-work related projects.

Even Lubrizol has co-authored papers on bearings on how the various materials chemical react in the engine.

If anyone has acess to SAE papers I highly recomend that you search these as they are gold mines of information!