so, lately ive had these thoughts of building a little pocket rocket to take to autocross/tracks in general, and something ive always wanted to do was take a 318ti, and stuff a m3 motor under the hood. ive heard of and seen a few of these already, now my question is if anyone on here knows of any precautions, unexpected things i might run into that i havent thought about yet? do you know someone that did this? maybe you did it? any help would be greatly appreciated......oh and would the e46 m3 motor fit into the e36 engine bay?

I think you'd get more suggestions or replies at the E46 forum. Nonetheless, good luck with the project.