SR20DET Main and Rod Bearings, OEM or aftermarket?

[JDizzle]

I'm in the process of rebuilding a redtop SR20DET before it's swapped into my S14. I plan on making a build thread soon whenever I make more progress. The motor actually looks great internally I'm just rebuilding this for peace of mind. I popped the bearings to take a look at them and they still look like new. I could reuse them but since new bearings are <$100 I figure why not replace them, right?

When buying OEM bearings you have a choice of different grades. I see the markings on my crank and know which OEM's I need to buy but would rather get Clevite 77's since they're coated and arguably better? From searching around I see all aftermarket bearings are a one size fit all, no grade, just different in aspect of STD, oversize, etc..

If I were to buy Clevite 77 STD size bearings, will the crank need to be machined since they are not available in various grades? If I plastigauge the Clevite 77 bearings will they fall into OEM specifications? Since my crank is still good I would rather not have to machine it. IF aftermarket bearings require machining because of the lack of grades I will not run them and buy OEMs.

[logr]

No machining necessary. I have used both. The OEM usually have higher oil pressure. I prefer OEM because they are matched to each journal but either seem to work fine.

[Tower240sx]

I would personally run ACL's sourced from Calico coatings.

However whatever your preference for aftermarket bearings, they will work (as logr stated) without any machining as long as the crank is still in spec and I have no reason to believe otherwise given your description,

The grading Nissan uses breaks the tollerances down into .0002" grades this is fantastic, it really is. It helps their engines live for 200,000 miles. It is overkill at almost every level.

DO NOT use plastigage for anything other than amusement, I have at my disposal very accurate measurement equipment (I run an aerospace manufacturing company and make satellite parts all day long) and have verified (back to back) the inaccuracies of plastigage, like if I had used and believed the plastigage I would have run a tollerance so tight the motor would have spun bearings on startup... plastigage may have been ok at some point in the land of .0035 clearances on main journal chevy's but DO NOT try to gauge bearing clearances on something you care about with it. If you don't have the proper equipment take it to a builder and see if they'll check the clearances for you, shouldn't cost much at all.

If you are (and it sounds like you are) dropping the same crank back in the same block with no machining you'll be fine just getting standard sized bearings from a reputed company (ACL, Clevite Etc.) and dropping them in.

Hope that helps

[Your Mom]

I've used oem and calico coated acl's this time. can't say i've had much of a problem with either. but next time i thinking i'll just get oems and get them coated. I didn't like only having one size fits all idea.

one thing i learned if your gonna use arp main bolts you should get it line honed. unless your going for 500+hp id just use the stock main bolts. 400hp and under you'll be just fine with oem stuff.

[Tower240sx]

Why would you think ARP studs care more about the alignment then the stock bolts?

Please quantify

And FWIW the .0002 of difference in the nissan graded Bearings is less than the thickness (per side) that any coating is going to build up anyway so you'll need to order a grade that is 2 grades larger than you actually require if you are going to insist on chasing the .0002 difference...but you can't actually order any bearings 2 grades larger unless your crank is grade 1 all the way across...so scratch that.

[JDizzle]

No machining necessary. I have used both. The OEM usually have higher oil pressure. I prefer OEM because they are matched to each journal but either seem to work fine.

Thanks for the quick reply. I'm sure OEM's are great but the aftermarkets are coated and about the same price. Something about them being advertised as "coated" just makes me want to buy them lol.

I would personally run ACL's sourced from Calico coatings.

However whatever your preference for aftermarket bearings, they will work (as logr stated) without any machining as long as the crank is still in spec and I have no reason to believe otherwise given your description,

The grading Nissan uses breaks the tollerances down into .0002" grades this is fantastic, it really is. It helps their engines live for 200,000 miles. It is overkill at almost every level.

DO NOT use plastigage for anything other than amusement, I have at my disposal very accurate measurement equipment (I run an aerospace manufacturing company and make satellite parts all day long) and have verified (back to back) the inaccuracies of plastigage, like if I had used and believed the plastigage I would have run a tollerance so tight the motor would have spun bearings on startup... plastigage may have been ok at some point in the land of .0035 clearances on main journal chevy's but DO NOT try to gauge bearing clearances on something you care about with it. If you don't have the proper equipment take it to a builder and see if they'll check the clearances for you, shouldn't cost much at all.

If you are (and it sounds like you are) dropping the same crank back in the same block with no machining you'll be fine just getting standard sized bearings from a reputed company (ACL, Clevite Etc.) and dropping them in.

Hope that helps

Thanks for the in depth response. A friend of mine who is building his motor (6G72) recommended that I use plastigage to double check the clearances.

Some of these aftermarket bearings are offered with extra oil clearance. Is that something I would want or just the regular standard? This isn't going to be an all out project, just a stock motor rebuild on a S15 T28R.

[JDizzle]

I'll be using reusing the OEM main bolts because I heard that was fine and have a new set of ARP head studs. Just thought I'd throw that out there since you guys are talking about main bolts.

[Tower240sx]

extra clearance means shorter engine life and will anticipate heavier weight oil being used...

For a normal freshen up rebuild I would go with the standard sized bearings.

[CodyAce]

While I'm not knowledgeable enough to spout the advantages of the race coated ACL bearigns, I will say I've never EVER had an issue with Nissan (ka, sr, FWD and RWD) OEM bearings in any of the engines I make. Granted not one of them is a pure race engine (they are all namely street cars that see abuse) but I still can't say I've had one lick of problem. Plus cost isn't that bad.

Edit: Thanks

[Tower240sx]

Edit: Np ^

[Def]

All the big power SR guys like Enthalpy/Epstein etc. have suggested going up 2 sizes on the stock mains, or just going to the biggest size all across. Supposedly SRs/KAs are a bit tight from the factory for "hard usage."

[CodyAce]

Never EVER used or had a problem with with nissan bearings...it seems a word is missing somewhere cody

Thanks

[Your Mom]

Why would you think ARP studs care more about the alignment then the stock bolts?

Please quantify

And FWIW the .0002 of difference in the nissan graded Bearings is less than the thickness (per side) that any coating is going to build up anyway so you'll need to order a grade that is 2 grades larger than you actually require if you are going to insist on chasing the .0002 difference...but you can't actually order any bearings 2 grades larger unless your crank is grade 1 all the way across...so scratch that.

i'm sure the arp's studs don't care much about anything. i had 2 machinist tell me that if you going to use the arps and torque them to arp specs, the main caps will bend or deform slightly to where the bearing clearance will be too tight. thats exactly what happened to me, crank would not turn. use factory bolts at factory torque spec, all is good. just saying don't spend the extra 100 on arp mains unless your ready to spend the extra 200 to line hone the mains. For me the whole problem with ACL's is doing your own measuring, which is very hard and expensive to get the right with the right equipment. your best just to give it to a shop. but if you just buy the oem bearings correctly its just pop in and go. I wouldn't see an huge need to have clearances checked, not saying i wouldn't just saying if there was no damage to the bearings when your removing the old ones than I wouldn't worry that something has changed.

This is the biggest paragraph i've typed in a forum for a long time. i'm starting to understand why lots of people don't even use forums. I'm not helping anyone nor if your like me will my experience matter to anyone but yourself, and preaching them online is a stupid waste of time. my kid just woke up....

[cazman]

Nissan went to a **** load of effort to reproduce modern day bearings as decent as their old lead 240z era bearings. Once the no lead law came in they re developed.

No citaions but if you search, youll find people used to use the old nissan bearings in cosworths and such.

[Tower240sx]

This is the biggest paragraph i've typed in a forum for a long time. i'm starting to understand why lots of people don't even use forums. I'm not helping anyone nor if your like me will my experience matter to anyone but yourself, and preaching them online is a stupid waste of time. my kid just woke up....

WELL FWIW I appreciate the insight, I wouldn't have thought about the extr clamping force and what it could do to the bearing cap but that makes good sense once it's on the table.