I'm fitting a turbo to my 617 engine, and was planning to copy the STT turbo kit where the oil return line is connected to the oil drain plug. A hose from the servo on my w123 fits perfectly to the drain plug hole, using the "banjo coupling" and the bolt from the servo. The only difference from the original would be that the flow will be more restricted, and then the question is, is it good enough?

Of course the first advice to myself is to replace the whole oil pan, but I only have the turbo, and I wanted to try this shortcut. Any opinions on this matter will be appreciated.

The oil coming out of the turbo is more like foam. HOT foam. It should dump into the oil pan above the oil level. It can backup into the turbo if the drain in any way prevents a freefall into the pan. When it backs up to the turbo, it leaks past the seals. I put a Callaway kit on an '84 Jetta GL one time. Had to drill and tap a 1/2 inch pipe thread hole into the back of the block! Had to be in just the right spot to clear the rods. Lemme tell you, you feel like you can never measure enough when you are about to put a hole in the side of a perfectly good block. Go to a salvage yard and buy a pan off a dead engine. You'll sleep better.

NON-turbo 617 engines don't have the oil cooled pistons & other parts that will make the block stay together. Everyone I've ever heard that tried ended up with a blown motor. Return must must be adequated sized. Its not just an MB thing.

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Brian Toscano

"I'm fitting a turbo to my 617 engine"
Bad idea unless you add the other pistons, the oil squirters, the other bearings, and you may need to put a different crank into it...Why not trade that one for an already turbo'd one... so it will last and serve you well...?