I made up some oil drain flanges for my turbos the other day and now I am second guessing the size. I made the flange with a 3/8 NPT and was going to use a 3/8NPT to a -6 adapter and run -6 line back to the pan. I could also get a 3/8 NPT to -8 adapter and run that, but I am concerned with the bottle neck at the adapter. What do you guys think?

I would go larger. On my systems I use at least 1/2" NPT for the nipple/adaptor and then use at least -10 in braided or 1/2" in tube.

The way I did it was:

1) cut out the oil drain flange out of 1/4" plate steel & drilled holes
I used a gasket as a template

2) get some 3/4" 18 gauge pipe and weld to flange and make all necessary
bends using the steel pipe. Weld -10 or -12 AN male steel fittings on the pipe.

3) port the steel AN fitting to match the pipe ID before welding

4) use straight -10 or -12 AN stainless steel hose with straight ends.
This is cheapest & easiest to assemble.

5) use the 3/4" pipe to make the oil pan inlet along with another -10 or -12
AN steel male fitting.

6) VERY IMPORTANT --> look at where the oil will return in the pan. Make sure it is above the oil line with margin to spare. Make sure it is not right at main cap blocking the oil from entering the pan.

You can never have too big of an oil return line.

Buddy of mine is doing hsi first turbo setup. Was going to run -6 but got advice from several places recommending at least -8, so that's what he's going with.

i'm running two -8 lines, but my drain is in line with a main cap, so as to not have the oil hit the crank while it's spinning.

I have one setup with the oil entering at the main caps. It is OK to do, but it gets tight at the front of the pan and needs to be done properly. As you go back on the pan there seems to be more room at the main caps. I was trying to give him a warning to watch for this.

i'm doing it at the #2 or #3 main cap IIRC, i haven't been in the garage in a while, but there seemed to be 1/3" clearance at least at that main cap from what I measured before I drilled out the holes and welded in the drain bulkheads. I am impressed with that truck build and I'm sure as I go along I'll have questions for you

The one I have with the oil entering the main caps is up near the #1 cap. It is right below the mech. fuel pump plate. It was a pain to make keeping the inlet as high as possible on the pan and keeping a slight angle for oil flow. I had to make it that far forward because of the second gen. camaro A-arms get in the way of putting the line more to the rear.

On the truck the pan inlets are more toward the rear near the knock sensor and oil filter. They are above the stock internal tray. I have some pics around here somewhere of the truck pan.

With the truck finished, I started fabbing a single setup for the camaro over the Winter.

The oil draining from a std turbo is very foamed up from the 100,000 rpm shaft speed. I'm running -10's from a 1/2" NPT port. Make sure the drain is the lowest part of the turbo (clock the center housing as needed to make sure the feed & drain is vertical), the drain always runs downhill, and dumps above the oil level in the pan. If there's the least bit of restriction, you'll get oil blowing by the seals. Ball bearing & exotic seal turbos might be more tolerant.

Thanks guys, it looks like I am going to just purchase a set of the -10 flanges.

Speedwaymotors, Summit Racing, and Racepartsolutions.com sell steel weld on -10AN male fittings if you want to make your own. You could drill out the 3/8" NPT to 1/2" and weld the fittings on.

True but, I need a gasket anyways. The aluminum ones are pretty reasonable and the come with gaskets. Has anyone used RTV instead of the gasket?