Turbo drain line

[chrishallett83]

The center section of the turbo is sealed, not open like a bucket.

[fabr]

YES,it is open like a bucket.  A bucket with a hole in the bottom.   Yes,it is sealed , but, it is open to atmosphere(crankcase)at the drain line once the oil is past the bearings  . It is sealed at the turbine and compressor sides and "sealed" on the oil inlet (pressure) side with the pressure feed line , but open at the drain line to atmosphere(crank case).  There is no pressure in the drain line of a properly installed turbo. Period.  If there is pressure after the bearings there is something very wrong with the installation of the turbo. The pressure stops after the oil has passed through the bearings. Oil after the bearings is under no pressure.

[Odyknuck]

Too clear 2 points up first.
1) The Turbo has a brand new center section.
2) The Turbo is mounted above the Engine with the 10AN X 14" drain line points straight down.
Based on my experience with the Garrett T3  (new or used) if your supply  too much oil pressure (50 to 80PSI) and rely on a gravity drain it will push oil past the seals.  It did the same thing on the VW motor with a different Dry sump setup and the drain line dumped into the valve cover offering no restriction to flow. BTW this was a brand new broken in motor.  When I put a T3 on the Subaru (used motor with 200PSI compression on all 4 so no blowby)with out the restrictor it pushed oil passed the seals (BTW Dynamic). I added the restrictor and it stopped the leakage except on occasion. Now back to you statement about a quart in a quart out. I totaly agree with the concept and thats why I feel if I remove the restrictor then the volume of oil will increase and a dedticated scavenge line will remove the oil fast enough to allow more oil thru the center section and not back up. Currently it shares a scavenage line with the main line from the oil pan. So when going up hill it is taking more oil from the path of least resistance, the oil pan.

Link to Subaru Turbo motor swap:
 http://www.woodsbuggy.com/index.php?option=com_jfusion&Itemid=10&jfile=viewtopic.php&f=33&t=6013

[fabr]

Point one-new center or old unless seals worn out should be no issue.
Point 2- turbo above or high mounted is good.
Quote-"Based on my experience with the Garrett T3  (new or used) if your supply  too much oil pressure (50 to 80PSI) and rely on a gravity drain it will push oil past the seals." Then the drain line is inadequate. It cannot push oil past seals unless oil is trapped in centersection. All there is to it. ANYTHING that will allow oil to pool in the center section will cause smoke. So with that in mind you have the oil drain line pointing straight down when car is level. Correct? No bends or anything and you have no smoke issues at all while car is relatively level. Correct? IMO, and that's all it is, when climbing a hill the car may be at 45degrees or more from level. All of a sudden that line is NOT pointing straight down and the oil is now trying to drain down a slope. Add a small bend and you have a line that will not drain. Trouble is that adding a scavange line will not normally pulll any more oil out. WHY,you ask? Consider a drinking straw, when you suck on it you are able to pull liquid from it (flow) BUT if you restrict it(flow) you will only be able to pull an equal amount to what enters. You cannot evacuate it unless air is entering the other end. If it is more liquid it will only displace an equal amount of liquid. In other words if the line won't drain properly with gravity a scavenge line will do little if any good to prevent the pooling of oil in the center section.  Oil pooling in the center section is the problem that needs addressed. If I was to use a dedicated scavenge line it would have an air bleed in the drain line that is plumbed into the center section directly.  I have seen that done with an adapter(spacer) on the bottom of the turbo  with a tiny(.060) air bleed and hose that connects the spacer to the crankcase. To that spacer the drain line is connected below the air bleed. Doing so allows the scavenge line to actually scavenge the line instead of just pulling a vacuum on it.