Bearing discussions

Hey all I have been looking for what would be best for my application and have came up with more questions than answers. SO I was thinking I wouyld start a thread where you could explain what is best for what applications. I have noticed there are many differnet bearing designs from each manufacture. The common differnces seem to be half, 3/4 or full groove, coated/ uncoated, 2 layer and 3 layer as well a a hand full of different materials that they are made with. Which are best for hot street engines? Or is it more important to just have a proper cleance and screw what the bearings are made of. I am just rebearinging my stock bottom end and want it to hold the nitrous and 7k rpms the best. What about cam bearings? I have looked at the durabonds specifically and they make 3 differnt cam bearings. I would think a performance application with higher spring pressures would require a harder bearing to keep from going out of round.

I have just some hair brain ideas about this. I think full groove bearings would be good for a N/A motor but with nitrous wouldn't you have a significant loss of bearing surface?

Please educate me!!

The old wisdom on this is you don't want full-groove bearings for pretty much the exact reason you describe. Smaller bearing surfaces mean that the peak loads on them (lbs. per square inch) are significantly higher on a full grooved bearing. Too much "edge" where oil is exiting the edges of the bearing, not enough flat area for a good oil film to create the "wedge" action that really keeps the 2 parts from touching eachother.

That's why you'll see the vast majority of SBCs with grooves in the upper bearing half, but the lower half in the main caps is just smooth and flat without any groove.

Proper machining and clearances on everything are always job one, though. Best bearings in the world can't save you from improper clearances or bad machining.

7000 RPMs on nitrous is a little outside my experience. 6500 on spray, though, I've never had problems with fairly common and inexpensive Clevite tri-metal performance replacement bearings.

The best I have found are the Clevitte "H" series. They are tough enough to take a beating and don't cost an arm and a leg.
IMO coated brgs are not necessary for the normal performance build.If the clearences are right and the oil pump is sufficent the "H" series will get it done.
Quality and construction of the brgs are essential,price don't matter.

Agree with the Clevite "H". Take a look at http://engineparts.com/motorhead/techstuff/brgselec.html

Rich

King, Federal, Clevite, who really cares? I know guys winning races with any of those bearings. I've had great luck with all three myself so until one of them starts sending me checks, they're all good. :)

I'd worry more about getting a high quality crank with good surface finishes so it doesn't take out your favorite bearing unexpectedly.

-Mindgame

Me three... I run some coatings on them which they now sell coated H series.

So from what I am gathering here, the tri metal bearings seem to be the prefered animal, and for coatings, they are really for when the build requires more than normal parts, such as a complete forged high rpm asssembly?


The "coated H" that you are refering to Bret, are these the new "Z" designation? Just from reading the link that Rich posted, I would think a P bearing would be best for High rpm stock bottom end that would see alot of big end stretch on the rods, as it has a higher eccectricy,or did I miss the lesson here?

It also seems that all of the bearings are made for cranks with large fillets, for us guys not running such a crank are we giving up bearing surface for no reason when using these type of bearings?

I think they are the Z series.

If you had a lot of stretch in the rod bores of the rods the higher eccectricy would help. Or you could use them to run tighter bearing clearances since you measure bearing clearance in the verticle portion of the bores not the lateral.

You only need as much bearing surface as you need. Any more just adds friction. If you are using a crank without a large radius in the edge of the journal then you probably don't need the extra bearing width in that application too.

Bret

Ok that makes sence now, I guess I will get P series rod bearings, and run a set of H half groove mains since I don't need the coating of the Z? This would seem to be the best of both worlds and keep thing inside my budget. Any more guidence before I order?

Get "H" series rods and mains that are uncoated. Ya won't be turning it 8000.

Easy old guy, some of us aren't scared of that coating coming off!

I do agree that the H is what you want, don't overthink this.

;-)

Easy old guy, some of us aren't scared of that coating coming off!

I do agree that the H is what you want, don't overthink this.

;-)

Just suggesting what works and no special training to install.
Tell him to get coated brgs and not telling him he will more than likely have to polish his crank for brg clearance is a mistake.Yes I check EVERY one I use.
All the coated brgs I have seen are .001-.0015 tighter than an uncoated. I have been forced to used them to get the right clearance.
That IMO is not overthinking the situation.

Coatings are a wonderful thing-- for somebody else.
Ever had a set of ceramic coated pistons that the coating came off in less than 50 miles and it looked like ya threw a double handful of sand in the engine. Had to trash the block (bored to much) replace the valves and seats and get a new set of pistons.
And ya wonder why I don't use coatings.

I really like coated piston crowns for FI. Coating the exhaust valve face may not be a bad idea either, though I haven't done it yet.

Rich

Calico is the only coating place I could find a listed thickness of their dry film coating. 0002 - .0004".

Swain and PolyDyne say it wont add thckness. I would think .0004 is substaintial in a bearing application.

I really like coated piston crowns for FI. Coating the exhaust valve face may not be a bad idea either, though I haven't done it yet.

Rich

Rich,
This was back in '92-'93 and there must have been a mistake in the install of the coating.
Don't have the money to experiment with coatings if that is what it does. The people who did the coating wouldn't help and took no responsibility for their f*** up. Put a bare set back in and no problems. Yep cost me a ton of money 'cause I was the one to suggest it,Duhhh
Ya know the trick of the week type thing.
That was my first and last experience and that Mustang was blown,pretty fast too.Ran some mid 9's back then.

LR: given an experience like that, and that nearly all great running motors get along without coatings, I can see why you feel that way after an experience like that. I am not sure that coatings do any good, it may all be voodoo. The logic seems compelling, but reality/data trumps logic EVERY SINGLE TIME.

Rich

Calico is the only coating place I could find a listed thickness of their dry film coating. 0002 - .0004".

Swain and PolyDyne say it wont add thckness. I would think .0004 is substaintial in a bearing application.

Get a set and check them the one that I get from the local speed parts will dial guage at least .001 smaller than the same brg uncoated.
That has been my experience and I know if they don't make 1 thousands under brgs for an application I can get coated to tighten the clearance.

LR: given an experience like that, and that nearly all great running motors get along without coatings, I can see why you feel that way after an experience like that. I am not sure that coatings do any good, it may all be voodoo. The logic seems compelling, but reality/data trumps logic EVERY SINGLE TIME.

Rich

Yea,they seem to fine small amounts of HP with the coatings know but ya now the saying burned once-- burned twice = my fault.

That was my first and last experience and that Mustang was blown,pretty fast too.Ran some mid 9's back then.

Dang, that is fast for a Mustang! :lol:

Now before I get 30 people telling me how fast some are let me help you out.... that was a JOKE!

I have never used a coated bearing but I am all ears. I'd like to see independent data that shows some benefit if anyone has it.

In my mind, a hydrostatic bearing doesn't need a coating.... unless that coating helps the oil wedge in some way. Maybe a gain in bearing life when you look at cold start conditions but how much?

As for piston coatings, I use Swain Gold Coat and have never had a problem. I remember back in the late 80's when guys were having flaking problems and the like... just as LR described. I stayed away from them then up til the time I saw a Swain coated piston that had survived numerous trips in a Pro Mod motor. I was sold. I've used their coating on exhaust valves, exhaust ports and headers with zero problems. Highly recommended if you have the extra money to spend. Only after putting it in all the right places first though.

-Mindgame

Dang, that is fast for a Mustang! :lol:

Now before I get 30 people telling me how fast some are let me help you out.... that was a JOKE!

I have never used a coated bearing but I am all ears. I'd like to see independent data that shows some benefit if anyone has it.

In my mind, a hydrostatic bearing doesn't need a coating.... unless that coating helps the oil wedge in some way. Maybe a gain in bearing life when you look at cold start conditions but how much?

As for piston coatings, I use Swain Gold Coat and have never had a problem. I remember back in the late 80's when guys were having flaking problems and the like... just as LR described. I stayed away from them then up til the time I saw a Swain coated piston that had survived numerous trips in a Pro Mod motor. I was sold. I've used their coating on exhaust valves, exhaust ports and headers with zero problems. Highly recommended if you have the extra money to spend. Only after putting it in all the right places first though.

-Mindgame


The Swain stuff THAT good?
Might have to try some,if they stand behind their stuff.
Piston tops would probably be as far as I go. That's for some of these people that like to live on the danger side of NO2.They would rather lean a shot down rather than spend to get a larger system.
Needless to say they don't live on that side very long.

I bet Rich would put in a vote for them as well... I know I do.

The coated bearings from them as well I'm a fan of, not cheap but for startup or times when you might have a oil problem they are worth it. Keith Dorton kinda sold me on this. You don't need them all the time so KISS definately applies here.

Bret

So would my application benefit from them or no? I am rebearing-ing(is taht a word) my engine due to the pick up comming uncovered and would like to give it all the help I can in this department.

1racerdude, you edited you comment a couple of post back, it origanlly said something about the P rod bearings being grooved, I looked a couple of places and didn't see where they said they we grooved, just the P series mains. The statement below is why I would think I would use these bearings. Sorry if I am overthinking this, because I am. ;)

Use the P-series rods where extremely high RPM's cause severe rod bore close in. This is typically indicated by nearly full parting line to parting line shaft contact with bearings having less eccentricity. Use P-series mains where higher eccentricity is desired to narrow bearing contact patterns and to provide increased oiling to rod bearings. Rod bearing oil starvation is typically indicated by polishing and smearing of the bearing surface possibly accompanied by discoloration predominantly concentrated at the axial center of the bearings.

Swain is where I go for the gold crown coating, sounds like Bret likes them too. The prices have gone way up lately. Their original TBC (thermal barrier coating) is up to $24.50/piston. That's $196 if you have a V-8 and decide to coat all eight pistons*. The top-of-the-line "Gold Coat"" is now a whopping $42.50/ That's $340/set. So, if you "go for the gold" and use JE (my fav pistons), good rings and pins, you are talking $1,200+ for a set of pistons!!! Get the skirts coated for another $120, add in some shipping and maybe taxes and you approach $1,500. The bearings are pretty cheap, $41.50/set (rods or mains).

As MG said, put it in the right places. Usually, spending it somewhere will have a better bang for the buck. But if you need it, you need it. The two motors I am currently involved in have very different needs. The crowns in the Camaro, with boost and N20, needs all the help they can get. Piston failure is a common way for a high boost motor to go out. The race car has a mild NA BBC turning just 6,500rpm, no need for coating the crowns or anything else there.

Think about what you are doing before randomly throwing $$$ at it. This is not a great stategy (voice of experience). But don't overthink. If you don't already know about the "P" bearings, you probably don't need them.

Rich




*jk

I'll keep this simple.

I use exclusively Clevite rod/main bearings, Use Durabond cam, coated on the race motor stuff. Yes the clearances have to be massaged in most cases.

I don't do much with coatings on crowns and chambers, I have seen as recently as 2 years ago coatings coming off on some high EGT motors, I'm talking 2300* egt diesel pullers.

Ok I think we have beat the coated horse to death now. I am still between the H's and P's

A little excerp from the link that Rich posted

Use H-series bearings with crankshafts that have oversize fillets and where engines run in the medium to high RPM range. H-Series bearings should be used if contact patterns obtained with P-series parts are too narrow. Contact pattern should ideally cover 2/3 to 3/4 of the bearing surface.

How do you figure this contact patch? It seems to me like to biggest reason for these H bearings is to run the cranks with oversize fillets, is this true? Also I looked in summit and the only H series mains they offered were 3/4 or full groove. Would these still be the ones I am looking for or am I not seeing the halfs? The article listed also says P series mains come in full groove but I can only find them in half? This is getting worse on my end, what would be my main distration to running the P's in stead of the H's? Thanks for you patience guys I just want to do this once with the right bearings.