Turbo oil return line, need ideas on what I can use
 

Ok, I'm in the finishing stages of my Turbo Carrera. I have almost everything plumbed up. For oil supply to the turbo, I tapped into the banjo bolt on the passenger side rear (rear of the car) and ran 3/16" tubing to the turbo.

Question #1: Do you think this is too small? I know too large is bad, as it floods the turbo. Should I go up to 1/4", or even larger?

Question #2: I think I can plumb the oil return back to the timing chain cover. It is a tight fit, about 3". The angle isn't too bad...it'll be close. But I don't want to use copper tubing on this line; too small of an area and I won't be able to get it bent right. Plus I fear vibrations may cause it to leak. I would rather use some sort of a rubber hose and clamps. There is really no oil pressure on this side of the turbo, but the oil coming out will likely be VERY hot (250-300 degrees is my guess). Can ordinary rubber hose handle these temps? If not, what do you suggest?

Colby

On my '77 turbo the oil feed is probably about 1/4in. I know a LOT of oil gets pumped out that pipe - I cranked the engine over to diagnose a timing chain problem with the turbo off, and I could not believe how much oil shot out the turbo feed line.

I haven't tried them myself, but several threads lead to Aeroquip:

http://www.racerpartswholesale.com/aqp.htm

These guys make high quality oil lines and fittings. Personally I wouldn't use a simple rubber line. Let us know what you wind up using.

Ok, I have heard that the KKK turbos use more oil and when converting to a Garrett you have to use a restrictor or too much oil can go to the turbo (per Protomotive). So if you're around 1/4" on a KKK, then 3/16" should be perfect on a Garrett like mine.

The problem with my return line is I have so little space I have no room for Aeroquip fittings. That is why I wanted to go with something like barb ends and a rubber hose.

Colby

Ok, I found out that regular rubber hose has a rating of 300 deg. Think the oil coming right out of the turbo is hotter than that? I wouldn't think so...

Colby

Colby, heat sin't the issue with rubber tubing. The problem is that rubber is not oil resistant. The oil will eat away at the rubber and cause a leak. You need to use something like silicone tubing.

Mike
86 Carrera t

Interesting.... any idea where (short of a speed shop) I could get silicone tubing? Auto parts store, home improvement stores, or is this a specialty item?

Colby

Just called an auto store. Transmission cooler line in 5/16". That should do the trick!

Colby

Colby, 5/16 or 8mm line is too small for a return line. There is no pressure at the oil drain of the turbo, so you need to use at least a 1/2" line.

Mike
86 Carrera t

Ok, I'll hunt down either silicone hose or transmission cooler hose in at least 1/2" diameter. That should to the trick; hope there's enough space in there (I'll know soon).

Mike: Do you think 3/16" tubing to the turbo is ok? Was the banjo fitting on the rear passenger side of the engine bay an ok source to tap?

Colby

Colby, I am not sure what the conversion to inches is but the reccomended tube size for the oil inlet piping for a Garrett is a -3 line and fitting (dash 3). I use a tee fitting off the oil pressure switch. I am not sure if teeing off the right banjo bolt would limit flow to the right chain tensioner.
Hope this helps!!
Do you have any digital shots of your progress? I would love to see!

Mike
86 Carrera t

That was my concern; compromising flow to the chain tensioner. But everywhere I wanted to tee off of had a serious cramp in space. Do you have a pic of where you tee'd off and how?

Yes, I knew -3AN was the size to go with and that equates to 1/8" NPT, but says nothing about internal diameter. No one (not even Summit Racing) could tell me the internal diameter of a -3AN hose.

Colby

Re: pics....I haven't taken any yet because I've always had it "partially together". I'll have to borrow a friend's camera and would rather do it once it is mostly assembled, not just in phases. I hope to have it in such a stage soon; the oil system has been the real bugger (especially the return line).

Colby

Colby, here's a pic of the oil line and hareware used, not on my car, but on an SC I recently turbocharged. For the line and fittings, all I had to do is tell my local Aeroquip dealer that I want a -3AN line of my desired length and thatb was it.

Mike
86 Carrera t

ATTN: Colby
 

Hi Colby,
What did you end up doing for your turbo return line? Got any pictures?
Colin

Mike: Where did you get the T fitting from?

Colby: Can you post pics of you progress? Are you doing a rear turbo configuration? Any details of your install would be appreciated.

Thanks,
Rick

Unfortunately, I scrapped the turbo project quite some time ago. I had collected many of the parts, and had a good idea of what I needed. Then I graduated, got a new job, moved, bought a house...and got engaged (handing the power over to her sealed the project's fate). I also began to realize just how much $$, even doing most of the fabricating myself, it was really going to cost. The risk to the motor was also a major factor. Should a lil whoops blow the motor, my dad would kill me (I still owe him for the car) and I would not have the cash to fix it. So I instead focused on modifying the brakes, suspension, and interior getting it ready for weekend racing. The motor also has 260k miles on it; not a good time to introduce it to a turbo. When I rebuild it in a couple years I may supercharge or turbocharge it.

But to answer your questions; the oil return line was a dilemma I had never resolved. I saw no easy way to plumb it back into the motor. I was leaning towards going right into the cam chain cover, but angles from the turbo to the motor were of concern...

Colby

In case anyone is looking at this thread for reference, AN dash numbers are in 1/16 of an inch for the ID of the hose. -3 = 3/16", -4 =4/16" = 1/4", etc.

Oil Supply and return
 

Here is a photo of my oil supply (-4 AN) and oil return to the left chain cover 3/8" NPT.
Pressure fed from sending unit (idiot light)

http://forums.pelicanparts.com/uploads/Oil Supply1.JPG
Gravity return to chain cover.

http://forums.pelicanparts.com/uploads/Oil Return.JPG

The reason I was asking for details is that I'm almost done putting together my '77 930 engine, and I only have the oil supply-to-turbo line.

I was thinking about fabbing both the return line (turbo drain tank to pump), and the pump-to-main oil tank line using Aeroquip hoses and fittings. But I don't know what width hose to use, or the type of fitting that would screw into the cam-driven oil pump. It sounds like 1/4" hose (-4 AN) would be OK. Now, anyone know about that fitting on the pump? I'm also keeping a lookout for secondhand lines.
Colin

The oil return should be bigger than the supply. I had a 9/16 hole put in the chain cover for the 3/8" NPT Tap. It is a 5/8" oil hose connecting to the turbo about 4 inches long.