I'm putting a turbo kit together - home made manifold and Garrett T25 from a Nissan 200sx 1.8.

The donor for the turbo has a 1mm about 40thou restrictor in the oil feed fitting coming off the block. I know a number of folks have used this turbo in their Miatas do you also restrict the oil flow or do you just let it rip?? It is a plain bearing type tubo not BB. On the same theme whatever turbo kit you have fitted do they have retrictors? The Garrett site makes reference to restricting flow to BB turbos but don't make mention of restrictions for plain bearing units.

I'd be glad of any comments.

Malcolm

 

Typically you want around .060". Although, turbos need very little oil. But what I'd do it put it together without it and see if you dont have problems with oil blowing past seals. If so then install it.

Tons of members here need them, tons don't.

 

i not running 1 and its scares me but has been good so far,ive got a gt2560.

 

It would be smart to take a look at the stock Nissan 200SX oil feed line (diameter? restrictor? etc.).

 

If you're going to look at a stock Nissan application, be sure to also check what kind of oil pressure they run. I see about 30psi at idle and aroun 70psi at WOT running Mobil1 20w-50synth. Less pressure, smaller line, restrictor, larger oil drain all contribute to getting less in and more out so you don't overpressurize the CHRA and blow seals.

A cheaper solution and one that has worked fine for me is to purchase a 1/8" aluminum pop-rivet and sandwich it between your feed-line and fitting at the turbo.

By the way, I asked this question about a month ago:
https://www.miataturbo.net/forums/sh...ighlight=rivet

Bottom line. Start with a 4an feed line and 10an drain. After a couple days driving if you're not smoking, you probably don't need one. Don't forget to check the compressor side to see if your blowing oil in to the IC. If there are no problems, relax. If you are having a problem. I'd start with the pop-rivet. If still problems, swap down to an actual .035 restrictor. If still problems, it's probably blown seals in your turbo.

 

Thanks for all your input guys.

I'm going with a 1/16" restrictor and we'll see what happens.

Having read all your info I figure that should be safe bet.

Thanks again

Malcolm

 

From Garretts site, not to informative except for actually giving a concrete number for the BB CHRAs.

Oil requirements depend on the turbo's bearing system type. Garrett has two types of bearing systems; traditional journal bearing; and ball bearing.

The journal bearing system in a turbo functions very similarly to the rod or crank bearings in an engine. These bearings require enough oil pressure to keep the components separated by a hydrodynamic film. If the oil pressure is too low, the metal components will come in contact causing premature wear and ultimately failure. If the oil pressure is too high, leakage may occur from the turbocharger seals. With that as background, an oil restrictor is generally not needed for a journal-bearing turbocharger except for those applications with oil-pressure-induced seal leakage. Remember to address all other potential causes of leakage first (e.g., inadequate/improper oil drain out of the turbocharger, excessive crankcase pressure, turbocharger past its useful service life, etc.) and use a restrictor as a last resort. Garrett distributors can tell you the recommended range of acceptable oil pressures for your particular turbo. Restrictor size will always depend on how much oil pressure your engine is generating-there is no single restrictor size suited for all engines.

Ball-bearing turbochargers can benefit from the addition of an oil restrictor, as most engines deliver more pressure than a ball bearing turbo requires. The benefit is seen in improved boost response due to less windage of oil in the bearing. In addition, lower oil flow further reduces the risk of oil leakage compared to journal-bearing turbochargers. Oil pressure entering a ball-bearing turbocharger needs to be between 40 psi and 45 psi at the maximum engine operating speed. For many common passenger vehicle engines, this generally translates into a restrictor with a minimum of 0.040" diameter orifice upstream of the oil inlet on the turbocharger center section. Again, it is imperative that the restrictor be sized according to the oil pressure characteristics of the engine to which the turbo is attached. Always verify that the appropriate oil pressure is reaching the turbo.

The use of an oil restrictor can (but not always) help ensure that you have the proper oil flow/pressure entering the turbocharger, as well as extract the maximum performance.

 

I believe that everyone should use one just to be safe. Puttin in 1 more fitting is easier than replacing a seal. If anyone wants them I carry a -4 male to -4fem with a 1/16 rest.
-Michael-

 

Couldn't have said it better myself...wait, I think I have said that very thing myself!

Only if by "safe," you mean running the risk of under-oiling your turbo and ruining it. I think it'd be far easier to just run the turbo w/o an oil restrictor for a short period of time while looking for smoke, oil in the charge pipes and other tell-tale signs of problems, rather than just installing the restrictor sight-unseen.