Ok I've gone through 4 engines already seeing if anyone had anything similar or something. First time I made a swap to 4l80 while waiting on trans I got my stock 6.0 and had it punched out and professionally did a 370. Had that installed along with a t6 turbo kit. Within a couple of days I lost oil pressure. Sent it back to my engine builder and said spun bearing ok rebuilt it replaced some connecting rods and replaced the lifters got rebuilt motor days later same thing. Next I found a junkyard 6.0 installed it same thing lost oil pressure we tore it down spun bearing. I bought a 4.8 installed it. Just this weekend that night lost oil pressure again. Was told maybe thinking the new trans converter is pushing my crank or having too much thrust clearance anyone had this problem

 

What a streak of bad luck! Hope you get it figured out.

 

Bearings spin when there is insufficient bearing crush, lubrication or clearance.

I assume you're spinning rod bearings?

You're either

1: knocking the bearings out from detonation (destroys crush and bearing gets loose in rod)

2: rod big ends are out of round (bad clearance)

3: too little oil clearance and side clearance for RPM (lubrication)

4: crappy machine work (crank journals OOR, improper surface finish, etc) (bad clearance, excessive wear which kills crush)

Thrust clearance issues kill the thrust main bearing long before rods. If you're spinning main bearings you could have a thrust issue, balance issue, insufficient clearance, overrevving, cap walk (stock fasteners) or ringing (flexing) the crank with high boost.

Examination of the bearings will tell the tale. Is there any pattern to the failure? Always the same bearing, what does it look like each time, etc?

 

Yes the first 370 was rod #5,6. Replaced them. The 370 is still complete right now. The junkyard 6.0. It was the rod bearings. We tore it down it was 4,5,6 bearings it spun. The 4.8 is still in the truck. Should be the tune. Cause the 6.0 and 4.8 was running when removed. Was told might be tune or detonation. We have a local tuner here. Maybe isn't doing something right or something. The engine builder here has built some good engines a friend has a 408 turbo they're pretty respectable haven't had any problems with it.

 

How much boost, what turbo, what fuel, and how much timing?

 

Boost is set up at 7 to start off at. Turbo is a Borg Warner s480 kb kit fuel is 91 timing not sure on how much my tuner gave it

 

I'm not really seeing detonation on the piston they kinda look normal. My cousin told me could be detonation also look at Pistons they kinda look good. But we shouldn't really see even after a day or 2 after driving. Just kinda weird 4 different engines the first 2 built by the engine guy and 2 other different ones doing the same ****

 

Well that doesnt really sound too out of line unless its a 12:1 engine on pump gas. I would say its something other than the engine. What kind of oil are you putting in it? Was there junk in the filter or oil screen?

How do the plugs look? If they are crispy your have spots it is probably detonation. How is the PCV system set up? If left stock you are probably sucking oil into the intake which would cause it to detonate.

 

Have you checked for a clog in the turbo oil line? I'm just under the idea that low oil pressure in 4 separate motors makes me look outside the engine.

 

Oil pick tube or O ring ? does it lose pressure slowly all all at once ?
what's your pressure reading idle, start up, cold, warm, running. ?