I decided to add an oil restrictor. So, I went to my local autoparts store and found a hydraulic fitting with a restrictor in it. I bought a drill bit and drilled the hole out to .070 and installed it on my turbo's oil feel line.

Before it looked as if my car had just done a burnout there was so much white smoke in my rear-view mirror. It would smoke worst under deceleration, some at wot and mild at part throttle, with none at a steady speed. Now I only get some under wot and some during deceleration, but it clears up quick. FYI 80 psi oil pressure wot, 70psi half throttle, 40psi cruising and around 20psi at idle. 15w-40 rottella-t oil.

Just thought I would share with everybody!

 

Is it a dual BB turbo? They usually put like a .040" restrictor in.

 

No it's a journal bearing I'm pretty sure. I know its supposed to be .065, but this is just for now until i get the right fitting ordered that isn't a brass hydraulic fitting. And that is the closest drill bit the parts store had. Been having trouble finding the exact gt42 that it is as it was on the car when I bought it and not sure of the exact specs other than it is a 76mm. Any help would be appreciated. I'm pretty new to turbos, I just got a screaming deal on this car as it wasn't running and I've just been working out all the bugs on it.

 

Definitely don't go any smaller then. Journal turbos obviously require oil pressure to form a hydrostatic bearing, BB turbo's dont, although they still have a 'journal' thrust bearing, excessive pressure just causes windage in the ball bearing.

Why is your engine making so much oil pressure? the 'seals' in the turbo may be damaged and restricting the oil flow could shorted the life of the turbo. How big is your oil return line and how steep of an angle does it return to the pan? if this becomes blocked at all, oil will take the path of least resistance and that may become out the seals/slingers and into the housings.

 

Well it used to be getting alot of fuel in the oil because it was running rich and thinning the oil out, thus loosing pressure after running it for awhile. So, I started running 15w-40 in it because it is thicker and then started tuning to lean it out abit. Is that really too much oil pressure? Now that it's not so rich I could run a lighter oil.

Also the previous owner had the turbo rebuilt because it was smoking alot. It didnt do it when I first got it running again, but got progressively worse. I searched around alot on ls1tech and found that alot of people where running ristrictors. So I figured why not? I've drove around for 50 miles or so since the restrictor install and no problems so far. Oh and .065 was the size people were recommending on ls1tech for a journal bearing turbo.

 

I put the car away for the night, but guessing that the return line is between 30-45 degree angle and 1/2 or 3/4 in line.