Turbo Oil Drain Location Drilled Out of Car
 

I have searched and read many threads on how to drill and tap a return hole in the oil pan for a turbo oil drain line while the engine is in the car. I am building an engine, so it is outside of the car. Therefore, I have a much easier time drilling the hole if there is a better location. I also am thinking about welding in a 3/8 NPT female bung rather than drilling and tapping the pan itself. This is in preparation for the TSE EFR turbo kit.

Has anyone welded in a 3/8 NPT bung before? I've seen several AN fittings welded in but can't find an example of a NPT bung. Is that because it is a bad idea?

If I put the hole further back on the oil pan instead of below the AC bracket, will there be a problem with clearing lines or anything in the car? Is there a better location than the standard under the AC bracket?

I am swapping a build VVT engine into a 1991 chassis.

https://cimg2.ibsrv.net/gimg/www.mia...28a228527d.jpg

This is exactly what you need, you need an aluminum one because your pan is aluminum.
As a matter of fact, the one in the photo I can sell you because I don't have a need for it. PM me your address and I will ship it to you for like five bucks. I think it's a -12, it has a 1/2" diameter ID.
https://cimg8.ibsrv.net/gimg/www.mia...f36c421a90.jpg

Why not send TSE an email asking them where the proper placement is for their kit? Or even a call...

Generally, the preferred setup if you have the access is to put a NPT weld bung in the pan over drill/tap only.

If only there were like twenty or thirty threads showing where to weld and what size to use.

I recommend -10 btw, but for some reason I have a -12 fitting. They say bigger is better. Do it, no balls.

Shiiiiiiit. My pan is off now, I might go -20.

-20. Why not. My last turbo drain was 2" id, but cause I didn't have a restrictor, it blew the welds on my intake.

There are locations that are less desirable.

For a FM-style kit with the turbo mounted between 2 and 3, I like a drain plug located just in front of the motor mount, in the space between it and the subframe.

http://www.codrus.com/miata/fm2r/oilpan1.jpg

http://www.codrus.com/miata/fm2r/dra...-installed.jpg

No idea how the EFR/TSE works with that.

--Ian

Or neither:

https://www.miataturbo.net/diy-turbo...e-story-89997/

Thanks for the info. There are many, many threads on how to add a drain hole to the pan with the engine in the car. I read through the TSE instructions, they also show how to put a drain in the pan with it on the car. I was wondering if there is a better location if one is not constrained to doing it with the engine in the car. I was thinking of something like what Codrus has, but I don't know if further back makes it difficult to get a wrench on the fitting, or if tubes are in the way, or whatever. Rearward of the AC bracket I can move the hole higher on the pan, although I don't know if there is a benefit to that or not.

If you want to drill further back, you may run into some as-yet-unforeseen interference issues between the oil drain and the lower radiator hose. The drain hose as-delivered will also certainly be too long for any position further back on the pan, so you'll have to build your own (our lines are crimp-fittings, not reusable). IMO there's no real-world benefit either, so it's a lot of extra work for no discernible benefit. I drill in the standard place even with the pan off the motor.

Then that is what I will do. Thanks