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/tec.../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.

;-)

 

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.

 

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.