This is the bottom of my VNT20 that's finally on my 1.9 IDI build, that's going into my passat gas to diesel project. I'm I safe in assuming that both the center holes are the oil return lines.
Thanks.
Maybe not enough information - it's a Garret GT2056.
Is that small hole threaded?
Looks like it's used to hold/seal something against the other hole that opens into the chamber.
If you want better guesses then show pictures of all the ports in the center cartridge.
i would be thinking that it may have a liquid cooled center section...
I have a gt2559v with a similar arrangement. On it, the small hole is the oil feed and the larger is the return.
I have a gt2559v with a similar arrangement. On it, the small hole is the oil feed and the larger is the return.
that was the other option i was thinking..
OP, is there an oil feed on the top of the center section in the normal position?
Yes - there is one on top too. But maybe rallydiesel is correct as I found this while searching, it's known as a oil inlet/outlet flange kit - but I couldn't find anything that goes along with it. As you can see in the pic the holes aren't threaded.

My error - after more digging the holes are tapped on the flange kit making for easy feed and drain solutions. The threads for oil feed is 1/8" npt and the threads for oil return is 3/8" npt. I've contacted the supplier to see if it'll work on a GT2056 as they have it listed fitting a GT1241.
Thanks to all for the info. Helped immensely as usual.