Ok bulit a motor an it ran great on 15 psi of boost but then it threw a rod bearing anyone kniw where to buy a good crank this stock on was balanced too. But didnt hold.

Ok guys i reread what i put am ment to say better bearings then acl i know the stock crank can hold like 800hp

ACL are good bearings...a spun bearing can be casued by a couple different issues.

- Debris (Oil Conatmination via sludge, dirt, or some other foreign body)
- Oil Starvation (Pump Failure, internal/external leak - or incorrect weight fluid for operating environment)
- Oil Breakdown (either too much heat, or gas contaminiation from running too rich, or not having the PCV system working correctly)
- Incorrect Tolerances (Just becasue its assembled to the factory spec does not mean it is fine for 800hp. The added pwoer creates more heat, and a crank/bearings on the tight side of FSM tolerances can cause a bearing failure)
- Incorrect Machining on the Crank

- and finally actual Bearing failure due to manufacturing defect, whcih is pretty rare.

Each of these causes different marks/damage to the bearing. I would diagnose the actual problem before blaming the bearing.

http://www.nb-cofrisa.com/docs/web_fallos_ing.PDF

Yeah ik what can cause it an these acl bearing are not the reace type just stock replace ment they couldnt handle 7300 rpm with 15- 20 psi so i want some better ones an caint find any thing realy for it but like the acl race, and clevite ones. I was wantn to know if anyone here knows a good site to get main studs an bearings that can hold that kinda rpm. But you are right the shop that put the block together may have f**ked up.

when using shelf bearing you need to plastigauge the things properly. A lot of things cause failure, on a fresh engine its normally clearance or debris.

stock nissan bearings can handle 7300 rpm.. I dont get down that way anymore but yeah.

I didnt bulid the lower end the shop did so not sure what made it go out but i will know soon tearing it apart an haveing it checked an i use coustom bearings i get the size of the crank the order the bearings and still gauge them to be sure.

Once you tear it down, post some pics, we can try to figure out what actually caused them to fail.

I will do that. Dose anyone know a good website to order acl race or clevite race bearings? Witch is better to, if anyone knows?