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Discussion Starter #1
I finally installed all my turbo components and now my oil pressure is much lower than it was prior to install. I was expecting a small drop since another part has to be fed oil, but not as big of a drop as I saw.

I have an HX35/H1C being fed with a -4AN SS line, and a -12AN SS return. I arrived at these sizes by measuring the stock feed and drain sizes that came on the turbo from the Cummins engine. And also lots of reading on the Holset thread on the DSM boards.

I'm running Amsoil Z-Rod 10W-30. Before the turbo I had about 80-90psi on cold start, and when warm it would sit at about 15psi idle, and around 40psi at 3k rpm. I'm not sure the redline pressure. Now on cold start I get 40psi, and at idle it is sitting around 12psi. And when I rev the engine it seems to hit a wall at 40psi.

The min spec is 10psi at idle, so I'm bareeeeely above that, which is slightly worrisome, but not the biggest concern of mine. What I'm concerned about is that I'm not getting enough pressure up top. The min spec in the manual is 50psi at 3k. I'm never seeing above 40psi, even when the oil is cold. I'm assuming this is because the oil pump cannot flow enough volume to keep the pressure up because of the size line that is on the turbo.

The whole, "holset blowing seal thing" seemed, to me, to originate from drain lines that were too small, that is why I went with a -12AN return line. So I figured I should stick with a -4AN feed. But now I'm worried that it is too big. Should I be worried? Should I switch to a -3AN feed? Could there be not enough oil to sustain a higher pressure at higher RPM's due to the increased volume necessary due to the turbo? I have it filled up to the second dot...Thoughts?

I have a dyno appointment on the 24th of June (12 days from now) and I'd like to get it sorted out by then.
 

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Use a restrictor,

youre bleeding off all pressure to the turbo,

Like Draining your Jugular...

How's your brain feel?
 

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Discussion Starter #4
Use a restrictor,

youre bleeding off all pressure to the turbo,

Like Draining your Jugular...

How's your brain feel?
Are you running a Holset? Have you read the Holset users thread? I might downsize to a -3AN line, because I agree with you, I believe that my the D oil pump doesn't flow enough volume to keep the pressure high enough with a -4AN feed line. However, I won't be running a restrictor. Unless you consider the -3 line a restrictor.

I used a -3 feed and everything was fine with my set up.

Just throwing that out there
Which turbo are you running? I'm thinking that switching to a -3AN might be the way to go.

In general, I wouldn't mind hearing a few more Holset users experiences.
 

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I ran -3an open too,

but found a little healthier engine oil pressure and no different turbo performance with a restrictor.

With a larger Holset, it makes sense to say that it would require more than a smaller turbo, but you have to find an equilibrium with the rest of your engine.

I value my rod bearings over almost any turbo bearing.

The Turbo is an accessory.

It does not turn your wheels.

You could get an adjustable restrictor and find where your engine oil pressure looks adequate,

or try different sized fixed restrictors.
 

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Discussion Starter #6
Very good point. I'd rather rebuild a turbo seal than an engine, that's for damn sure. What turbo are you running? What size restrictor did you put in? I'm still weary of going down to anything less than a -3AN sized hole. What was your oil pressure with an open -3AN line?
 
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