f

I looked into this earlier this year, and even talked to a few profs that gave me some good reading material. I was tired of people saying journal bearing turbos needed a restrictor.

I found that over-oiling will turn ball bearings from a rolling element bearing to a sliding element (ala journal bearing)...which is bad. If the ball bearings stop "rolling" between their two contact surfaces you're in trouble. The low contact area makes a very poor journal bearing, and they start to wear quickly...regardless of abundant oil supply. It's really a matter of surface pressure really...same forces as in a journal bearing...but much smaller area. Follow the Garrett advice Braineack posted and you should be fine.

Journal bearings on the other hand have a minimum pressure which is significant...and luckily often pretty low by design. Once you achieve this minimum pressure there are no other concerns with regard to the bearings. The only reason to put a restrictor in a journal bearing turbo is to prevent blowing oil out of the seals.

min liked to puke smoke on cold start before it died.

I guess I'll call BEGi and have them make a smaller one because I went with a .060 previously. How small should I go on a track car?

Go with what 0.040" like Garret recommends or a 0.035" like other people have used. It really has nothing to do with if you track your car or not. It has to do solely with oil pressure.

Neither do I.

this small:

'Oil pressure of 40 - 45 psi at maximum engine speed is recommended to prevent damage to the turbocharger’s internals.'

I've been running .035 restrictors for 30k miles on two (three?) different BB turbos. I've never seen a single drop of oil in my charge pipes.

Trey, it might be that heat shield that's getting the EWG hot. I wouldn't worry about it.

I don't know that he possesses the ability to not worry about it. Wishful thinking though.

I have no heat shield on it. Thanks for the heads-up on the restrictor.

I just shipped everything out so hopefully I'll have this car back on the street next weekend...there went my brake money.

How dare you disrespect blahhhh blahhh blahhhhhh. :hustler:

I'm getting better and starting to trust the car after another successful track day.

You won't "kill" a Garrett bb turbo by delivering high oil pressure to it. What this will do is force oil past the seals, which will then find a new home in your IC pipes and/or make for a smokey exhaust.

Once you fit a proper oil inlet restrictor, the smoke gradually goes away, the valdez in the plumbing clears up and all is well.

Oh, also, high oil pressure can nullify a bb's low-friction-ness by introducing a bunch of windage. But you won't hurt the bearing. Oil pressure that's too low, sure, that'll kill it.

remember all those posts about having the most reliable track car ever built?

I run that ATP restrictor too. Turbo wants it.

Well then fuck me. More misinformation from two sources, including ATP. Maybe I should get a restrictor as well, or call ATP and ask WTF?

Listen to Jkav, he's a turbu guru from Garrett.

I've learned a lot in my desire to have the most reliable turbo miata, and fallen victim to [insert signature here].

I guess I'll try the .035

hustler, I may have missed it but if you not seeing signs of oil getting past the turbo's seals then you're fine with the restrictor size you have.

EDIT: just saw that it smokes on startup. Hmm. I don't know if this is related to the turbo--oil pressure on a cold start isn't that high (relatively speaking) and cold oil is viscous and has a harder time working past the turbine seal.

That and Garrett site itself says run 40psi or .0035 restrictor with bb.