16G Oil Restrictor Help, Over 100psi Oil Pressure..

[jm1080]

I'am running no restrictor on my 16g and I noticed my oil pressure gauge idles around 5psi and when boosting goes to 80psi and max boost over 100psi (maxes out gauge). Now I bought a -4 base with .60 nitrous jet which is supposedly good for my turbo, now I was removing the oil feed line and I cannot seem to fit it in. So I remove the L shaped part on turbo where the feed line attaches and still nothing. Does this go on the turbo itself? If it does, the restrictor base is so small compared to the one on the turbo. I shot a pic to show (left is restrictor):

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Does it go on the oil filter housing? If it does, it is still too small to fit in, so where exactly does this go? This is real frustrating..

 

[eclipsetuner_21]

It goes on the turbo itself. The nos jet goes inside of it. Are you feeding from the ofh? Do you have balance shafts?

 

[jm1080]

Yea that is where I thought it would go, on the turbo itself, but you can see in the pic it is too small, when I tried test fitting it on the t25 it would just fall through the hole of the turbo.

Yes I'm running balance shafts and running through oil filter housing.

 

[eclipsetuner_21]

Does the one on the right fit on the t-25? If so shave the top of that one and install the nos jet in it. I can see how the one on the left is too small.

 

[jm1080]

Nope it does not fit either, but it does fit the 16g I believe. I guess I have to take the manifold off to do this? It seems there is barely any space.

Didn't want to have to cut it, but does anyone know the correct size for it to fit on the 16g? That way I can just return this restrictor base and get the correct size one.

 

[donniekak]

Run a stock 1g oil feed from the head. The 1g stock setup has a built in restrictor. Also if you are seeing 5psi of oil pressure at idle, you have some other problems waiting to rear their head.

 

[dsmfa9nutter]

5psi at idle? You have some serious issues you need to address before you start playing with the turbo.

 

[Weapon-X]

WoW ! WTF You sure your oil pressure is at 5 psi.? Is that a typo/error or something? For your sake I'm hoping it was.

 

[RadDsm]

Don't the MHI turbos already have a restrictor built-in on the feed inlet?

 

[dsmfa9nutter]

Don't the MHI turbos already have a restrictor built-in on the feed inlet?

When fed off the head, you'll get the perfect pressure. If you feed any turbo off the oil housing, you have to have a restrictor.

 

[jm1080]

I don't know how to run off the head, so I just did off the oil filter housing and yes 5psi, not sure why, but it was like that before and after headgasket job, rebuilt head, still the same. Car runs like new, so I don't know, I open the valve cover cap and there is good amount of oil pressure, not sure if it is gauge, I'm using prosport guage, but if it reads the oil pressure up top at high boost, then I don't know. It has been like that even with my old T25 for a long time and never any problem. When it starts cold it is around 25psi, but then as the car is ran and warm it goes down to 5 or 6.

 

[JusMX141]

Don't the MHI turbos already have a restrictor built-in on the feed inlet?

Not really.

The inlet is smaller than other journal bearing turbos, but it will still require correct pressure (and restriction, if necessary) to function properly.

Look at the 1G OEM feed line from the head, there is a .075" restrictor hole built into the banjo fitting at the end of the line nearest the turbo, meaning MHI turbos were meant for use with a low-pressure source that is also restricted.

 

[jm1080]

Just an update, I had to get another fitting that would fit my small fitting to attach to turbo. Now what exactly is the correct amount of oil pressure for a journal bearing or 16g turbo? Around 60max? Because this restrictor is I believe a .60 for journal bearing turbos.

Also when you guys said low oil pressure at idle is dangerous, 5psi at idle, what exactly does it affect? Like I said I have been running like this for 2years and have swapped bascically everything besides my bottom end, did all maintenance and still the same.

 

[SlowSpyder]

I would go .070-.090 for a mitsu turbo. As for your low oil pressure i wouldnt worry about it. Just verify that you have atleast 30-40psi of oil pressure by 3krpms and make sure your idiot light is working because that triggers the light at anything less than 4 psi.

Besides on my built 4g64 with some tight tolerances and no balance shafts with 10w40 my oil pressure is less than 10 psi at idle when fully warmed up.

 

[jm1080]

Got it! Thanks for that, was starting to get a little worried hehe.

Last thing, what is normal oil pressure for mitsu or journal bearing turbos, I mean max oil pressure?

 

[dsmfa9nutter]

5psi IS low despite what others may think. You should be around at least 15psi at idle and then +10psi for every 1000rpm. An example would be my own, I vary between 25-30 hot at idle, 90psi at 6k while wot and over 100 on a cold startup with 5w30. This is on a stock shortblock with nearly 130k miles on it and a bsek.

If you're turbo smokes, your restrictor is too big. To feed from the head, there's a port in the passenger side of the head, same side as the cas but right by the front.

 

[jm1080]

My turbo never smoked which was weird, as I heard if it is over 100psi it will smoke, not sure if it is my oil pressure gauge, it is prosport and this is the second sender I used... If my oil pressure was dangerously low at 5psi when fully warmed, then something would of happened by now and it is been over 2years with the same oil pressure. I remember my stock one would always be at the middle and when this new one I put, it was at 5.

Also one more question, what size is the oil restrictor on the right of the pic? Because the one on the left (the black one) was too small of a base of 1/8 NPT threads, not sure what MHI turbos use, wondering if it is the same as an hx35 as well as I plan on using the same restrictor when I swap turbos.

 

[JusMX141]

My turbo never smoked which was weird, as I heard if it is over 100psi it will smoke

This depends on how good your drain system is.

not sure what MHI turbos use, wondering if it is the same as an hx35 as well as I plan on using the same restrictor when I swap turbos.

MHI inlets are 12mm x 1.25.

MOST Holset inlets are 12mm x 1.50.

 

[jm1080]

Thanks Jus, just what I needed to know!

Well I installed my old restrictor that had a smaller port and now I'm getting about 90psi WOT

Also one more thing, Jus or whomever, where exactly can you find that size restrictor? I tried looking everywhere locally and nothing, not sure what exactly to search for online. Thanks!

 

[JusMX141]

I build my own restrictors; I haven't bought an actual restrictor for any turbo other than a ball-bearing unit.

 

[jm1080]

Nice to know Jus, when I buy my hx35 I will buy a restrictor from you as well

Also I noticed my oil pressure raises quickly lets say at idle to 2k rpm it goes to 40 and at 3k rpm it goes to about 70 and at 4k rpm it is 90, this is just revving. Not sure if that is how its supposed to be, but oil pressure still goes past 100psi even with restrictor. It has to be the oil gauge? Turbo does not smoke or anything, so I believe it is that

 

[dsmfa9nutter]

How are you reading oil pressure going to the turbo? Your oil pressure gauge is most likely reading the pressure the entire engine sees. There's a difference between pressure and volume as well.

 

[EclipticalGS]

Yeah if you have your gauge like running off your Oil filter Housing, you cant read your oil pressure going to your turbo, the only way to read turbo oil Inlet pressure is to literally have a sender screwed in right to the turbo oil inlet, or somewhere between the turbo oil inlet and the OFH on your oil feed line...I think your getting confused. ### if you just have the oil sender screwed into your Oil Filter Housing, that measures engine oil pressure.

I have 6-bolt w/ BSEK w/ no oil relief porting done, NAPA 10w-30, and I have cold start oil @ 70 psi...warms up and it sits at 12.5psi idle, 3000 rpms it's up to 50psi, 5000 rpms it's up to 80psi, redline around 7000rpms it sits at 110psi WOT, so i figured my oil pressure goes up 15psi per 1000rpms.

Good luck, if you think you have problems, just feed from the head, call it a day.

 

[jm1080]

Thanks for the help guys, yes I'm running the sender off the OFH, so I'm guessing those readings are from engine like stated. So how do people read their turbo oil pressure? I know you said if you put a sender on the turbo, but I see many people going off their engine oil pressure guage, that is why I thought how you read it. So everyone who is stating their turbo oil pressure gauge, actually has a sender on their turbo???

 

[dsmfa9nutter]

The real answer to your question? They don't have a clue/you're misunderstanding their post/they're bsing you.

The absolute BEST thing you could do right now to get rid of your worries would be to run the line from the head like you should have. That port on the head is specifically designed to have the right amount of pressure/volume for any oem mitsu turbo. I never understood why people would try to run oil from the ofh with a mitsu turbo, it only causes problems.