MyE28.com

Hello all,

I'll be replacing the oil pan on my NA m30 and would like to take the opportunity to drill and tap for a turbo oil drain. The block is a M30B34 and the oil pan is from an M30B35. Manifold will probably be from RSI. I plan to make a 1/2" npt drain and cap it for the time being.

My question: What is the best location for the turbo oil drain? The turbo FAQ uses the oil pan. I've seen others tap the block below the motor mount using an existing boss. I recall someone using the oil pan on an e12 and having a smoke screen on hard left turns (during autocross). Lower timing cover is another option I've seen suggested.

Thoughts on the perfect location?

In my experience, it would depend on charge pipe routing, and manifold/turbo position.

I used the oil pan location but a better spot for me may have been the block boss for a shorter more direct path. I didn't want to tap the block as i figured the oil pan could easily be replaced if it was somehow damaged, whereas it would be more work to replace/repair a messed up block. I also think the oil pan location offers more flexibility in terms of fittings and differing layouts.

Here's where I put mine:





My drain and turbo location. Obviously tight proximity with the charge piping.



I don't believe there is a single best location.

On the b34 I drilled into this boss and tapped a 3/4" copper pipe into the hole.



On the b35 I used this location.

This is on an m20, but it's in the same spot.

The highest location in the oil pan will be sufficient.

AFAIK all m30-based engines (m102/6, b34, b35, etc) have a boss on the block that you can drill out for just this purpose; it's what was done on the factory 745i's: http://www.r3vlimited.com/board/showpos ... tcount=215