So I have an 86 325es with a little over 250,000 miles on it. It runs beautifully now that I chipped it last week. But I'm seriously considering doing an engine swap on the car, since I have a lot of friends around my area that could help me with all the nitty-gritty of completely overhauling the "new" engine that I'd drop in. I've thought about getting another Eta block and just rebuilding that, but at the same time I've considered dropping in a different engine entirely. I've looked around here and there and I've gotten some ideas, but I was wondering, what some of you feel the best engine to swap to would be, or if I should simply get another ETA block and rebuild that with maybe an I head. I've looked on strictlyeta.com or .net, whatever it is, and I've read the entire section on the engine conversion that the guy does on there, sounds pretty interesting. He spends close to $3600 on the whole operation, which isn't bad. I just need some concrete ideas, I've heard the S50 and a few other engines mentioned, I just don't know which one I ought to go with. Any ideas folks?

Me, I'd go with an M50/S0 swap. But if you decide to go with a rebuilt ETA, I've got a block in my garage. $50. Comes with pistons/crank and a bare Super E head, but I believe it was developing a lower end noise when I pulled it.

you cant justify spending any money on an E30. The eta engine was designed for efficiency, and mine runs strong and efficient. But as far as performance potential I just dont think that its there. Even and M5x doesnt have a lot of performance potential for the money it costs. I am considering a 5.0 swap as well as everything else.