Let's talk about turbo oil restrictors

A good friend of mine has a '99 Civic Si with a JDM Civic Type R (B16B) that he had turbo'd by a local Honda guy. His old EBay turbo began leaking so he replaced with a new CXRacing unit. Fast forward 1k miles and the turbo has LOTS of axial play. I'm am leaning to the turbo being insufficiency lubricated. New turbo is enroute, just wanting to ensure it doesn't happen again. What restrictor should he use? My F2T powered MX-3 is running no restriction and I have the exact same turbo with 7-10k of problem free service. I know the CXRacing stuff isn't the greatest stuff, but for the $ its great. Please advise.

Because I can't be the only one that wasn't aware of the need for oil restrictors on turbos: https://www.turbobygarrett.com/turbobygarrett/oil_restrictor

Which turbo is it?

Its the CXRacing T3/T04E .50 /.63

Ball bearing turbos will have shaft play with no oil pressure present. As long as you're not making contact between the blades and the housing, it's probably okay.

We've not been using restrictors for the past 20+ years. Doesn't seem to affect oil seal lifespan on our Garretts.

In reply to Keith Tanner:

I knew sleeve bearing had some slop. I didn't think ball bearing would have any. Hmm.

Whatever hmm means, they do.

Oil restriction to a turbo seems like the very wrong way to approach it. Much oil, big drain would be my go-to.

On the Chrysler Turbo cars of the 80's Garrett specified a certain amount of oil pressure/volume and a 1/8" line suited that without issue. However they found the smaller line tended to break and cause engine fires during testing, so they upped it to 1/4" and put a restrictor in the outlet on the front of the engine. Problem solved and none were the wiser.

BTW, the returns were quite large, very short and very straight on those cars and they could still kill oil seals if you screwed the pooch too much.

So yeah, there's a spec for oil volume and pressure. If the manufacturer doesn't know it/provide it, then that would be worrisome to me personally. It seems like most modern turbos have improved seals and perhaps different bearing clearance specs, etc. its still good info to be aware of when specing out a turbo.

Keith Tanner wrote: We've not been using restrictors for the past 20+ years. Doesn't seem to affect oil seal lifespan on our Garretts.

I think that may be because the standard 6 foot long -4 line supplied with an FM2 kit is effectively acting as the restrictor. :)

So ball bearing turbos need the standard restrictor, journal bearings do not. EBAY journal bearings do, they take a bigger restrictor than youd normally find. If really would like i can pop the feed off mind and measure it, i dont have pin gauges with me but i can eyeball with calipers or you can google it. From what i recall they use restrictors because of shoddy seals and id guess not so great flow paths for the oil inside the turbo? Last parts a guess because journal bearings need good pressure and flow unlike ball bearing but hey its chinese and $150 off eBay so we can't complain.

I have the same turbo but in "57trim"

EDIT: add took over and i measured the restictor, the calipers fit in there and it's roughly a .073in (1.86mm) restrictor and it came with the turbo

Double edit: op if yours if fine this long dont do anything different, some need a restrictor some do not, its easy to see if its got one in the feed, usually its a fitting you can remove inside the feed side. Maybe he had E36 M3 luck or as you said didnt have enough oil pressure/flow in the first place.

codrus wrote:

Keith Tanner wrote: We've not been using restrictors for the past 20+ years. Doesn't seem to affect oil seal lifespan on our Garretts.

I think that may be because the standard 6 foot long -4 line supplied with an FM2 kit is effectively acting as the restrictor. :)

Possibly, although it's an 18" line on 1990-95 cars.

How's the turbo drain done? Double check that that's in good shape as well; if it returns below oil level in the pan or if it is too small diameter, you can run into some problems as well.

The other thing to consider is the fact that most people that add a turbo do not upgrade their oil pump. If you have a short, low pressure drop line going to the turbo and the turbo itself has a small pressure drop, you can actually rob oil flow from the engine. The restrictor can keep the oil in the engine, other wise it will effectively bypass the engine through the turbo.