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2G Turbo Oil Drain Line Angle

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Kai Hefner

Freelancer
480
272
Jun 21, 2018
Calgary, AB_Canada
Ever since I did a turbo swap I had a really slow leak from the turbo oil line (which I upgraded when I swapped but I guess it just didn’t seal right).
So now I paid for this oil drain line already made to make sure that it doesn’t leak. Was wondering, is this 90 degree into the oil pan too steep of an angle? I remember one of my old buddies said to watch out for the stuff, something about oil pooling in the line. Basically is the bottom of the 90 degree fitting too angled and will it cause issues?
 

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perfection - no.

does it work - sure

. ideally you want it flowing into the pan rather then stopping and being pushed into it but you will know if its an issue if you start pushing out out the turbo as it backs up
 
Thanks for the responses though!

Are these oil drain lines widely available as bolt-in stuff? I got this guy all sealed together at a good price and wondering if it's worth kitting together for people.
 
Do they make these oil returns in a flexible braided line in the correct length with the end couplings attached?? Mine is leaking too, and the hard line is a little crimped...it would be nice to have a flexible one!
 
-10 lines, everything can be purchased from STM

You mean something like this??!!....I was digging through a box of parts I had sitting around and found these! I think I just need the braided line...but these have barbs so I may just use a rubber hose and skip the bling..
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Just watched a short video here...
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looks like these push lock fittings are designed for the braided lines, and can be used without band clamps, if the correct diameter hose is used...but mine are the piano black fittings so the braided line would be too shiny....I'll just go with the plain black hose instead...all that bling just gives the cops more reason to write you a ticket and send you to the referee check....CA sucks like that
 
Ever since I did a turbo swap I had a really slow leak from the turbo oil line (which I upgraded when I swapped but I guess it just didn’t seal right).
So now I paid for this oil drain line already made to make sure that it doesn’t leak. Was wondering, is this 90 degree into the oil pan too steep of an angle? I remember one of my old buddies said to watch out for the stuff, something about oil pooling in the line. Basically is the bottom of the 90 degree fitting too angled and will it cause issues?
Yup. You've already downgraded from stock by going to 10AN and reducing the inside diameter of the drain line by 1/4", now you've added a sharp bend right at the pan which, on a gravity drain, is a bad idea.

You want the drain to turn upward as quickly as possible but with the least amount of a bend as possible to promote the best drainage. The only way this can be done is with either two 45's or a 60 and 30 fitting depending how far the turbo is placed away from the engine by the manifold selection.

Here's why you want the drain to turn upward quickly...the way our engines sit in the bay, the inlet at the pan is not the lowest part of the drain. This is a terrible design but it's what we're stuck with unfortunately. If the fitting at the pan on this car was a 45, the flow would be much better and it would keep oil from laying in the line as well.

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Yup. You've already downgraded from stock by going to 10AN and reducing the inside diameter of the drain line by 1/4", now you've added a sharp bend right at the pan which, on a gravity drain, is a bad idea.

You want the drain to turn upward as quickly as possible but with the least amount of a bend as possible to promote the best drainage. The only way this can be done is with either two 45's or a 60 and 30 fitting depending how far the turbo is placed away from the engine by the manifold selection.

Here's why you want the drain to turn upward quickly...the way our engines sit in the bay, the inlet at the pan is not the lowest part of the drain. This is a terrible design but it's what we're stuck with unfortunately. If the fitting at the pan on this car was a 45, the flow would be much better and it would keep oil from laying in the line as well.

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I'll have to double check the line size and my receipts, the inner diameter of the AN line that I used definitely wasn't 1/4" smaller than the stock drain tube.

My original plan was to utilize a straight fitting at the turbo, and a 45 at the pan, but the angles wouldn't line up. I don't think two 45s would have done it, but I never even considered using 60s or 30s. Wish this thread would have been around a few months ago when the motor was still on a stand and I could measure these angles without having to lay on my backROFL
 
I just measured, since my parts are still out of the car, and the inner diameter of my rubber hose is 5/8" but the inner diameter of the -10 AN fitting is only half inch... So it looks like it's a little bit restricted over the stock pipe.
 
Here is what the RTM -12an drain comes with...It's bulky but it drains exceptional. I had this kit (and have one on my Red Talon) and was going to install it on my Holset when @MorrisonFab came out with their kit and they asked me to do a "trial run" before they released it.
As you see, I went with theirs as it was much easier to work with and fit like a glove.
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the inner diameter of my rubber hose is 5/8" but the inner diameter of the -10 AN fitting is only half inch... So it looks like it's a little bit restricted over the stock pipe

This is the wrong way to compare. Diameter is not the same as area for flow rate. The area difference with 5/8 diameter vs 1/2 makes the 5/8", 56.3% more area for flow over 1/2". Do the math.
 
This is the wrong way to compare. Diameter is not the same as area for flow rate. The area difference with 5/8 diameter vs 1/2 makes the 5/8", 56.3% more area for flow over 1/2". Do the math.

I was never really good at math...but the 1/2" inner diameter is still less flow than the 5/8" right??
 
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