Hello community. I am new here. I've decided to do a 20b swap on my E46 M3. Since I have not found any swap kits out there or any other examples of this swap I wanted to reach out if anybody wants to help finding solutions. My mechanic is able to make custom engine mounts on the car. I want to stick with the Getrag 420G transmission as to not have to make any chassis modifications but any advice is well taken. If anybody knows a shop that specializes in engine-to-tranny adaptors please let me know. Aditional advice is also well-regarded.

 

welcome to the board.

from what i understand, those trannies are pretty robust, so i agree with keeping it if you can. maybe you can start here: https://collinsadapters.com/adapter-plates.html

i don't know anything about them, but i saw that they made adapters for both rotaries and BMW trannies, and i figured at the very least, they could tell you what measurements you'd need to take, even if they can't/won't build the adapter you'd need. i don't know how that would work with you being in PR, but questions can't hurt.

do you already have the engine?

anyway, it sounds like a fun project. i am/was a huge fan of the Queen St. BMW (even though it sounds like you're going with a much tamer build), so i would love to see your car and the process you'll have to go through.