How is the drain ran and what size ?

I cant see how the -4 is a problem .

What kinda oil pressure issue ?

 

The drain is -10 and it drops straight down from the turbo for about 12" before curving into the pan.

The oil press drips when in boost,it's been that way for a while. Was running 20w50 and it was acceptable,not right,but enough that I let it go. Been beating on it for a few yrs now and could see that the oil press on a pull was getting lower over time. Pulled the motor over the winter and the rod bearings were done. New bearings,main and rod,and back in the truck. Better press,now running 10w30. But still have the dip in press on a pull. Press is good to go everywhere else. I'm running a vacuum pump,10" on a pass,but had the press prob before I installed it,so thinking it's not a factor.

Here's a log shot:

 

I see these posts quite often and don't really understand them. You're thinking a -4 line is moving so much oil through the turbo that it's reducing the oil pressure and starving the bearings? The flow through the turbo I figure is controlled by the clearances of the turbo bearings themselves. That's like saying you need to reduce the dia. of your main oil gallery because it's moving too much oil past your main bearings.

And I've always run a -6 feed on my 475 and don't have any issues with oil pressure.

If I'm missing something obvious please let me know, I've been wrong before.

 

Sounds like you need a higher volume oil pump

 

Was the thrust bearing wiped ?

 

Mains didn't look bad at all considering the low press,it was the rod bearings that were beat all to hell.

 

Do you run the “stock” amount of oil in the pan? Or add “extra” due to what’s in the lines, turbo etc ?

 

I ran a 4 feed and 10 return on my S475, no rest. Pressure was rock steady thru a pass. Maybe your pumping the oil up top and starving the pickup.

 

8qt Milodon pan. I had a remote filter mount on it - Canton Racing.-10 lines - and removed it to see if it or the line size was a prob. It helped some. Going to disconnect the vacuum pump today and see if that has an effect. Been considering pulling and installing a HV oil pump,might try some 20w50 first for the hell of it.

 

I run an LS/S475 converted to an 80 billet, -4/-12 straight down into the timing cover. Fbody pan with improved racing baffle, but I also run 7 quarts of oil. Over 100 passes. No issues ever, but if you look at the logs, there is a consistent, momentary pressure drop at around 6000 in first gear. Drops from 55psi to 43psi, then up to 68 psi for the remainder of the pass. Its consistant, and its always done this since day one. Thrust is still at .008 where is was assembled at, and when the shortblock was disassembled last winter (driveshaft failure broke starter pad off the block) the bearings all looked like they had just been assembled. 20W50 VR1.

 

What's your clearances? I've ran 20/50 VR1 and 10/30 no difference in oil pressure. I'm .018-.002 rods and .003 mains. This is two logs, one mix (3)10/30 and (6) 20/50 1.5" below top of pan with 9 qts. The other (8) 10/30. I run a -4 feed and -12 return to the pan right under timing cover. S400 also.
I was concerned about mine dropping to the low 60s at 77-7800 near the end of the run.

Pan. Moroso Street/Strip Oil Pans 20141
Windage tray. Moroso Louvered Windage Trays 22941
Pick up. Moroso Oil Pump Pickups 24050
Oil Pump. Melling Performance Oil Pumps 10296 With factory installed high press spring.

 

I unhooked the vacuum pump and the oil press actually looks worse. Average press about the same,but it fluctuated a lot.

 

I really doubt that the turbo oil has anything to do with your oil problems.

It's a little weird that the bearing looks hot on 3/4 of the width. One edge is fine. But that is really hot. I didn't see anything about crankshaft damage. But I'm a little surprised that bearing didn't try to grab.

I'm not familiar enough with fords to help a lot. But how is your lifter clearance? On the chevy's, if your lifter bore clearance is big, you will lose a lot of oil and pressure there and have a lot more windage.
No chance that there is a crack in the oil pump pickup tube? Pickup getting uncovered maybe?

This is scary ground here. Until the problem is found, you are toying with disaster.

 

I made about 5 low 10 sec passes the week before I pull it down,LOL. Found a shit load of bearing material in the oil filter.I wondered about the uneven wear also. The crank looked fine, I just installed new standard size main/rod bearings and back together. Pump is new and pick up is good. No idea on lifter clearance, motor is the stock 90k shortblock that came in the truck. I did convert it to a HR, but don't remember anything wrong when I did it.