How dificult M50 to M20 swap

[Reckless_Kelly]

I've got an 89 525i M20 auto, and I'm looking at a wrecked 525i M50 with a 5sp. How hard would it be to put the M50 and tranny into my M20 car? I know I would have to relocate the battery, but would everything else e the same. Will the M50 run off of the M20 wiring harness and DME, or would I have to transfer all of that stuff too?

Thanks

[winfred]

you need the wiring/computer and for the most part it's plug and play, but the harness plug by the fuse box where the engine harness connects to the body harness is not always wired the same, the good news is usually the only wire that is moved is the one that powers the ac compressor. the diff ratio will be be different from the auto to the manual, no OD in the 5 speed means the 4.10 that's most likely behind the auto will have you buzzing fairly high on the highway, the shifter wiring is not hard to figure out to get reverse lights with the stich you just need to drop them down to the tranny, and connect the safety switch wires together so it will start, i can't remember exactly but i think the clutch switch wires are allready there for the cruise cancel

[joshua43214]

Buy the entire wreck, that way you will have all the parts you need.

It probably will be a big project, but should be fairly straight forward