GO FOR IT. Let me start by saying that everyone and their mother on this board is going to tell you that its not worth it and its too heavy blah blah( might weighs 90-150 lbs more, OMG!!! SO FREAKING HEAVY!!! WHAT WILL U EVER DO!!!)… it can be done and as a matter of fact I've heard it bolts right up with the factory Z motor mounts, only real space issue is that it sticks out about an inch, nothing some creative hood work wont solve. As far as power goes that engine starts with “280”hp with plenty of room to grow, considering all the US support that it has. I have nothing against the sr20det but as they say no replacement for displacement. Anyway search around, this is one of those ideas that ppl talk about but never actually do it, but there are plenty of posts on it, and a few from ppl who are working on it. as soon as I'm outta of college and I get a second car going I plan on swapping a vg30dett in my s13.
btw heres some reading you might find very interessting..
http://www.zilvia.net/f/showth...0DETT
when u search, search for vg30dett in an S13