turbo oil restrictor ( journal bearing )

[bongskag]

got a small bit of oil coming from the compressor side circlip area.

I thought restrictors were only used on BB turbo's turns out a lot of honda boys use them to limit the ammount of oil pressure going to the turbo,

I get a good 4bar oil pressure over 4k rpm all the way to redline .. and it starts up at 4 bar too until warm ( brand new oil pump lots of pressure )

this is around 58psi , I read that a turbo only requires 25-35psi to run all the time. and could be the reason for oil escaping the seals?, Ive been running 0.8bar boost which isnt really helping to keep the oil where it should be

does anyone know the correct restrictor size for this sort of pressure ? I am running an-4 oil feed line , standard unrestricted banjo bolt , and 3mm restrictor at turbo

the 90 degree oil return on the starlet is a major flaw . this is widely frowned upon by other tuners and mechanics, never knew until now!

my current oil return is the usual 16-19mm samco 90deg , I really thought this would be ok as lads run them with no probs.! Im thinking my problem lies within oil pressure side of things,

any knowledge would be greatly appreciated :teach:

 

[5e colin]

you can buy / mod a inline oil restrictor of 1.5/2mmmm i have that to as you have good oil pressure there so wont starve isseu

btw what tuby u using ???

 

[bongskag]

I was thinking the same , around 1.5mm , its a t28 turbo. the An-4 adaptor is just striaght through with no restrictor , td04's are deffinatly less fussy over oil pressure , must be built in restrictors

 

[Skalabala]

You might have a turbo problem bud. Extra sump pressure could also cause the problem.
But Going to 1.5mm/2mm might work. Not good to starve a journal bearing turbo.
And what oil are you using?
Some wet oil inside the compressor housing can sometimes pass as a normal thing.

What brand/age T28 is it bud?

 

[bongskag]

found some advice from the garrett website "an oil restrictor is generally not needed for a journal-bearing turbocharger except for those applications with oil-pressure-induced seal leakage"

using millers CFS 10w-40, its a new garrett turbo no worries with that.. I think my oil pressure is too high for the turbo, in combination with poor oil return route... here's the full answer from the garrett website :

A. 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.