I'm going to assume everyone in this section has heard of coating bearings and get straight to the point.

Worth it? Overkill? Bad idea? Better ideas out there?

 

If I'm working on a motor that's more than $10K, it's worth it. You can have Swain coat your set, but a coated set from Calico or now the new Clevite Tri Armor.

Bret

 

imho, if there is a film of oil between the part (cam, rod, crank) and the bearing during normal operation, i dont see what a coated bearing is going to change. only advantage i see would be the few seconds during startup or in a pressure failure you would have a little longer (a few seconds) to shut down before lockup. is it worth it? production engines last 100k+ without them. if your going to spend money on coatings, go with the piston skirts & tops, and maybe combustion chambers. again, just my opinion.

 

I would use them with a very high hp motor, especially a small block based on an OEM casting. Even a good crank will flex, and small blocks are more prone to this than big blocks due to the smaller journals and less block stability. Even if everything else is right, extreme loads causing flex and main bore distortion can squeeze out the oil film and lead to the potential for metal to metal contact. As the above post notes, coatings can provide a margin of safety under circumstances like that.

With a very hi-po motor, there is no substitute for getting everything else right. This includes main clearances that are a little "loose" to help avoid metal-metal contact as well as high quality main caps, stiff crank, perhaps partial block fill, etc. Coating the mains would be like icing on the cake in this scenario. I am putting together the latest iteration of the motor in the race car. Since it's relatively mild (~700hp/7,000rpm) for a big block I am not using coated bearings. The next version of the LT1 in the Camaro is going to have coated main bearings for the reasons listed above. ~1,000hp in a small block, especially based on an OEM casting, is a lot more stress than the same thing on a big block.

SBC mains = 2.45" = 4.7sq.in. CSA
BBC mains = 2.75" = 5.9sq.in. CSA (25% increase)

Of course, the crank is a little longer on a BB, negating some of the extra rigidity from the larger CSA. Crank stiffness is underappreciated. People concentrate on tensile strength. Yes, a forged crank is stronger than cast, but there are very few broken cast cranks in most usages. The added stiffness of the forged piece is a big part of what you are after when upgrading. The "lesser" forged alloys like 1053 and 5140 don't offer the tensile strength of 4130 or 4340. However, they are just as stiff. Both are ~25% stiffer than nodular iron. 1053 and 5140 are both less expensive than 4340 and are a good alternative to 4340 for a strong crank at a bargain price. You don't seem them used much anymore but are what GM used for hi-perf BBC forged cranks back in the day. I use a 5140 crank in my BB - got a few of them cheap when GM discontinued them.

Rich

 

Thanks for in indept info rskrause! This helps me alot. Does anyone know where to get coatings done on the bearings? I know of one place, but would like to keep my options open and shop around.

 

I used the coated Clevites - anyone can order them for you and it takes about a day to get them. The coatings take up a few more tenths of clearance, so be aware of that. In my case that helped me, since my clearances were a little looser than I wanted. So, instead of going with a mixed set of undersized halves, I chose the coated bearings, and never looked back.

 

I've used Swain Tech Coatings with good results.

 

Is you the REAL Unstable Bob Gable? And when will that engine be done?

 

Gave ya 3 sources above.

 

Sorry, i was looking for for website or a phone number to a company. I Don't have alot of free time to do a lot of research anymore. Had to get another full time job to help pay for the new motor.. need to get it done in time to beat a buddy who's got a blown mustang that loves to talk ****

 

Just Google Swain Tech, Callico or just get the coated bearings straight from Clevite. You just put a K at the end of the PN you are ordering.

Bret

 

Yep, it 'tis me. N' as far as the engine goes:

Dominion 32V headed 396 LT1 currently being built @ Bauer Racing!
Estimated completion time: 800 gazillion beers from today!!!

I don't think Bret is even up to 100 gazillion beers yet...

 

OK, well, I was hoping for a more technocological answer, but that'll do for now

 

Trying to get the Dom valvetrain into the 21st century so it works. [EDIT] I'd give out more details
...but then UB would have to shoot you for knowing. I don't want to tempt him.

Keep praying and savin' UB!