david fracolli

I have a SFR stage 1 turbo and as stated before in previous threads I am having a severe smoking problem on boost. I know a have a blow by problem but I was also wondering if anyone else who is running this turbo installed an oil restrictor or knows if this turbo needs one?
Thanks!!

david fracolli

Been talking with a couple of people and from the comments I got it appears that a restrictor would not hurt anything so my next question is where can I get one from?

wi54545

You can get one from Lowes. Mine was 3/8 allen head set screw 20 or 24 pitch. You may have to dremel some thread off the top of the set screw to make it flush (do it off the turbo obviously). I drilled with a 1/16 metal drill bit. Works for me! BTW I have an SFR stage I or II (dunno which).

david fracolli

The reason I asked was because I was driving the car hard last night and after I shut the engine off the thing continued to bellow oil smoke for a good 10 minutes!

Laust Pedersen

Until a certain size that is true, but what good does it do?

The internal bearings (two radial and a thrust bearing) act as internal oil restrictors. I could see that lowering the oil pressure to the bearings with a restrictor could make a very slight improvement in internal friction, but choosing the right restrictor size is a very delicate balance between irrelevance and turbo destruction.

Excessive engine leak-down will through the turbo oil drain pressurize the center section and make the turbo bleed oil if the crank pressure is larger than the boost- and/or the back pressure, particularly if the dynamic seals are compromised.

Laust

david fracolli

Laust, are you saying then that there is no reason to install an oil restrictor then?
Seals should be good as the turbo has only 700 miles on it.

Crazy Eddie

Hey David
Hope all is well
I haven't followed this but it would seem obvious that the person to ask this question would be Tim at SFR ?? Who would know better than him ?
Even if you didn't buy it from him I am sure he would assist you in this area ?
Best of luck
Regards
Ed

david fracolli

Actually I did ask Tim before I bought the turbo. I was just wondering if anyone with this turbo was running a restictor and if they were if they had seen any improvement with it.

pk951

As far as I can tell with my garrett a to4e I put a restrictor plug in with a 1/8 drill bit hole. That's been two years now, and the turbo is fine. Do a serach lot's of info on that.

Eyal 951

What is the purpose of the restrictor. Will I need one for my to4e built by innovative?

Porsche-O-Phile

More oil supply never hurt anything.

Except if you're Alaskan wildlife I suppose.

Crazy Eddie

Did he say, get one ?
The reason I ask is, a guy I trust a lot on this board thought that the old stlye Garrett that I had, was a very good canidate for a restrictor ( I don't know what SFR turbo is )... From the sound of this thread it sound like its a Garrett?
Regards
Ed

MichelleJD

I have a toasted SFR stage II and it has a restrictor. Unfortunately, I've only been able to hit boost once before the turbo disintegrated

Laust Pedersen

It would be unwise of me to give you specific advice on a turbocharger that I don’t know in detail.
But if I should come up with an advice then: Fix the cause of the blow-by. I know it is expensive and time consuming, but trying to minimize the effects of excessive blow-by is a never ending frustrating activity.

That said, the question still stands to anybody, why a restrictor?

All the turbochargers I have had my hands on and the cross-sectional drawings I have seen of others in books and other places, all have had a fairly traditional design with two (radial) journal bearings and a thrust bearing, all being pressure lubricated and the flow being “automatically” regulated by the thicknesses of the oil films.
Each radial bearing has two oil films and inner and an outer and the floating bearing therefore spins at about half the shaft speed. The radial bearing is oil fed from the outside and the oil has to overcome the centrifugal forces to reach the inner journal through centrally located holes in the bearing, hence the need for pressure feeding. A restriction (orifice) will reduce the pressure and at a certain size will begin to starve the inner journal. As the bearings wear they need more oil flow, so a restriction that may work initially could be a problem later on.

Let me ask a little more provocatively: If the engine is leaking oil, will it then be a good idea to restrict the oil flow to its bearings to reduce the leakage?

Laust

Mike Murcia

I've heard that the KKK turbos used on our cars are designed to handle higher oil pressures than normal turbos can handle without leaking. I think it has to do with the center section having more robust seals.

There were a bunch of problems with aftermarket turbos for the 951 in the days of Huntley. They blew a lot of oil and the thought was that the center sections were not as hearty and robust as the KKK. Therefore, the restrictor was born.

Years later I heard that the real problem was not that the Turbonetics or Garrett center sections were poorly designed, but rather poorly built. It seems that the suppliers that the tuners were using were giving them turbos built with parts worn past spec. As a band-aid fix, the tuners were intalling restrictors.

What's the truth? Is a KKK center section designed to handle higher oil pressures better than a Turbonetics or Garrett? I don't know. Do people run aftermarket turbos without leaking oil? Yes, but it seems that it is important to know that your turbo was built by someone who truly knows their stuff. Vitesse and Vic (Pauerman) seem to have a good track record for this, but I believe that they both use some sort of restrictor.

I would not want to have to guess at what restrictor size to use. If you have a sufficient leak that you need a restrictor, than too big of a hole could not stop the leak. Too little of a hole could starve your turbo of oil and kill it with the first boosted run. (Maybe this is what happened to you, Michelle.)

I am now in the process of getting a turbo upgrade together. I am going with a genuine KKK turbo because I do not want to deal with the headache of leaks, smoke and restrictors in case my supplier has a bad batch of worn parts. I realize that there are more modern turbos out on the market, but reliable upgrades are more important to me than milking the last HP out of my engine.

As a disclaimer, I have not had any personal experience with a Garrett or Turbonetics turbo. I've just been around for a long time. Just thought I'd share what I've heard over the years.