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Automotive Powered Off Road (AKA: Buggys, Jeeps, Trucks, Etc,Etc. ) => Motor and Drivetrain => Topic started by: Odyknuck on October 19, 2009, 08:06:37 AM
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I "T" ed the Turbo drain into one of the Scavenge lines on the Dry Sump System. It seems to work well however on occasion (Hill climbing) I believe the scavenge line would get overloaded and not pull from the Turbo enough and the oil would back up into the Turbo, meanwhile the pressure side is still pumping oil and forces it past the seals and into the exhaust. I recently picked up a Peterson 4 stage oil pump and plan on using one of the Scavenge ports just for the Turbo drain. My question is two fold. 1) Will the pump try and pull the Turbo dry and not keep enough oil on the Bushings? and 2) should I remove the .060" resticter from the Supply line to allow more flow. It would seem that would work better. The system would push a lot more oil thru the Turbo and help it cool better. Thoughts please. Thanks In advance.
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Ball or plain bushing?
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Plain Bushing Garrett T3 60 trim.
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I have heard that plain bushing turbos are prone to oil starvation when using dry sump . I'd call Garrett and get the real pro's advise on this one though.
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Matter of fact I think I read that in the FAQ's at Garrett. Maybe not tho.
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I went thru all of the FAQs and Tech support on the Garrett site and the only thing I found was to use a scavenage pump when the Turbo was lower than the Sump. I believe Corvetts use a scavenage system on there twin Turbo cars. If you think abouts the dynamics of it with the pump pulling on the the Turbo you create a more negative pressure on it thus allowing more oil to flow thru the Turbo Supply due to less restriction. For every ounce of oil removed another ounce will replace it (Differential Dynamics) increasing flow thru the Turbo and actually not allowing the pressure to push past the Seals. Thats why I ask about remove the restrictor to Insure the flow rate. I added the restrictor because I am running around 80 PSI cold and 50 PSI hot at 2000 RPM hot oil pressure. The oil was always blowing by the seals even with the current scavenge setup until I added the restrictor.
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I personally don't see a problem but a call to garrett is cheap insurance. I ran a scavenge line with a very small pump that mounted on the busa with low mounted BB turbo and had no problem . IF you need a Motec 12V oil pump I have a nearly new one that could be had. The motec is the same one as Lingenfelter uses on the twin t-boes vettes. Motec is the best by far for this purpose.
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Make sure that the drain line from the turbo has a big enough i.d. and no sharp bends in it. It's way easier to reliably pump oil through a line than it is to suck it out the same line...
When you look at a factory setup, the turbo feed line is a little steel pipe, about 1/4" i.d. The drain hose is usually at least 1/2" i.d., if not bigger, and it usually goes in a gentle curve from the bottom of the turbo straight into the side of the sump, no more than about 12" long.
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My lines are 3AN supply and 10AN return.
Make sure that the drain line from the turbo has a big enough i.d. and no sharp bends in it. It's way easier to reliably pump oil through a line than it is to suck it out the same line...
When you look at a factory setup, the turbo feed line is a little steel pipe, about 1/4" i.d. The drain hose is usually at least 1/2" i.d., if not bigger, and it usually goes in a gentle curve from the bottom of the turbo straight into the side of the sump, no more than about 12" long.
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Cripes! You'll be right then. Maybe a pressure reducer on the way into the turbo, to get the oil pressure back down around 20-30psi will stop it blowing oil past the seals?
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I already have a .060" restrictor in the supply line, however with a dedicated Scaveange return line I am going to remove it to increase flow thru the Turbo. I believe the scaveange will keep enough pull on the oil to not allow the oil to pass the seals. Withe the current scaveange being shared with one of the Sump lines it only pushs oil thru the seals on occasion with climbing.
Cripes! You'll be right then. Maybe a pressure reducer on the way into the turbo, to get the oil pressure back down around 20-30psi will stop it blowing oil past the seals?
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You need to think about something. Just adding additional scavenge ability(vacuum)will not "pull" more through anything. For any extra scavenging to occur you have to have an equal amount coming into the turbo. In other words you can only scavenge the same amount as is supplied. 1 quart in = 1 quart out. No more ,no less. The only way adding scavenge capacity will help is IF the centers section seals are shot and THEN you MIGHT keep the center section clear of excess oil due to air leakage past the seals. If that's the case you need to rebuild the turbo,not put a band aid on it. Removing the restrictor should make no difference. I'm thinking you have a turbo that is just mounted too low for gravity to keep the oil drained from the center section when climbing hills and added scavenge capacity will not cure that. It also sounds like a turbo with bad seals (needing rebuild)or an engine with enough blow by (needs rebuild) that it pressurizes the crankcase inhibiting the gravity drain back. The case pressure trying to push the oil back to the turbo.Remember that unless you have a killer dry sump system it will cavitate on steep hills and not be providing any pressure so the case pressure can easily "stall" the oil drain back in the turbo center section. Bottom line is that high vacuum will not pull a thing through a hose if the other end is blocked off. I do not feel that adding a dedicated turbo scavenge section will solve the problem. Mask it maybe but cure it? Naw.
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Cripes! You'll be right then. Maybe a pressure reducer on the way into the turbo, to get the oil pressure back down around 20-30psi will stop it blowing oil past the seals?
As soon as the oil hits the center section of the turbo the pressure goes to nil. UNLESS the drain line is restricted. Should be no need to lower the pressure at all. IMO it's a worn out turbo that needs attention UNLESS the unit is positioned to hinder oil drainback when climbig a hill.
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As soon as the oil hits the center section of the turbo the pressure goes to nil.
You sure about that? The turbo center is sealed, with pressurised oil going in, and out through the hole in the drain fitting. If the oil supply flow is sufficient to fill the oil chamber and galleries in the center housing (which it should be), then where did the pressure go?
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That's why the drain line is much larger than the feed line. When planning a turbo install it is very important where you mount the turbo and the drain line. ANYTHING that hinders the free flow of oil to the sump will cause pooling of oil in the centersection and you will have smoke as a result. The oil in the drain line is under no pressure unless there is a restriction in it . Example: water in a garden hose(torbo feed line) is under pressure till it exits the hose end(centersection) where the pressure goes to zero. Now direct connect the water hose to a 5 gallon bucket and imagine the water from the hose going into the bucket(centersection) with a 3" hose(turbo drain line) in the bottom. Will there be any pressure in the 3" (turbo drain)line?
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The center section of the turbo is sealed, not open like a bucket.
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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.
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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
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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.