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

Colby · 05-04-2002, 10:22 PM

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

1bar · 05-05-2002, 10:01 AM

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.

Colby · 05-05-2002, 10:05 AM

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

Colby · 05-05-2002, 01:27 PM

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

Mike the mechanic · 05-05-2002, 01:39 PM

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

Colby · 05-05-2002, 03:45 PM

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

Colby · 05-05-2002, 04:27 PM

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

Colby

Mike the mechanic · 05-05-2002, 06:24 PM

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

Colby · 05-05-2002, 07:16 PM

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

Mike the mechanic · 05-05-2002, 07:49 PM

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

Colby · 05-05-2002, 08:20 PM

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

Colby · 05-05-2002, 08:26 PM

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

Mike the mechanic · 05-06-2002, 04:55 AM

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

cowtown · 03-10-2003, 09:00 AM

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

RickM · RickM's Garage

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

Colby · 03-10-2003, 12:18 PM

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

JWest · 03-10-2003, 01:30 PM

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.

tsuter · 03-10-2003, 02:07 PM

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)

Gravity return to chain cover.

cowtown · 03-10-2003, 02:36 PM

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

tsuter · 03-10-2003, 04:05 PM

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.