Which engine swap would make most sense for me, if any.

[clydesdale]

I want more power. I have 260,000 miles on my 87 325is. It still runs, handles and looks good. But, it doesn't have a lot of power. What is the best route to go? Engine swap? Rebuild the current motor? If rebuild, how do I get more power and still have a smooth driving car? Thanks.

[Gunni]

Check out r3vlimited and e30tech which are alot more US based forums.
Both have a giant knowledge base.

I´d say a M52B28 or a S50B30 (US) or a S52 would be a great upgrade path for you .

[FormerMember]

S52 is the US-version S50 ;)

M50 or M52 is the way to go when looking hp/$ and consumption ratios. Those are cheap and good engines and easily good to 220-250hp. When aiming around 300hp then S50 is the choice.
Anything upwards from there will start to cost quite a lot and can easily be achieved with superchargers or turbos.

But as mentioned earlier, check out r3vlimited and e30tech. There're lots of information (and also lots of BS)..

[E30BeemerLad]

Judging by where the original poster lives, I'd be putting in a LS1

[Blitz]

As your in the US I'd imagine there are more ETA engines available. So M20 2.7?