How much power are you looking for and how much are you willing to spend? For a decent upgrade in power with minimal modifications, go with the 3 liter out of an E46 330i. Physically it'll bolt right in and you just need to reflash or swap DMEs for it to run as if it had been built that way in the factory. If you've got more time and money and want more power, go for the S54 from an E46 M3. It requires more work and parts to be done right, but it still is essentially a bolt-in proposition. If you don't mind a real project and want loads of power, LS swaps aren't unheard of. I think it's mostly fabrication that's needed there so you're not exactly hacking the car apart, but it's certainly much more work.

 

More realistically ask what your budget is for the swap. That will dictate what can and cannot be swapped. Tangent pretty well set up your 3 options ranging from minimally cheap to "whats another couple thousand here and there"

 

If you do an LS swap, there are a few companies that make the motor and trans mounts already but you should do some reinforcing.
But as mentioned, easiest would probably be a 3.0 with the DME and be pretty easy.

 

Thanks folks I appreciate the Input, 330 sounds good, what's the latest year that has it? I'd go thru the trouble and expense if I can get a newer fresher one 2010?

 

For ease of installation you'll want the m54b30 engine, so right around 2005 will be the last year for that. Any newer and you're dealing with an engine that was never used in the E46 and you're going to be adapting wiring harnesses and trying to get systems to play nice with each other that never were designed to.

 

So if you drop the motor and computer from a 330 into a 325 will the auto transport mission play nice with the new computer or is the tranny controlled by a separate computer?

Garry

 

I think the tranny has what's called the TCM. It communicates with the ECM and/or the DME.

 

The biggest hurdle will be switching from throttle by cable (2000 323i) to a throttle by wire system of the newer engines. I suppose you can replace the electronic throttle valve with the manual throttle valve, but who knows what that will do to performance. The 323i DME can be re-flashed to whatever engine you install. You wont need to replace it, I have successfully done so when I upgraded from a 323i engine to a 328i engine (both throttle by cable). The trans computer is separate and will work fine regardless of the DME coding. Physically, all engines are virtually identical and will bolt right in.