Building an E61 550iT6?

[lucas999]

Hi All,

A few months ago I picked up an '07 530xiTa to replace my E90 335i6. The 335i was having lots of issues, and I really didn't trust it anymore. I am in college in CT during the school year and can't fix my car here, so I catch up/get ahead on maintenance when I'm back in Maine during breaks. The 335i was too needy for this schedule, so the wagon (my 6th BMW) has been a nice replacement in terms of reliability.

However, while I love the comfort of the wagon and the body style (have always loved wagons), I am definitely missing the power/handling of the 335i (for some strange reason!). Also, I never realized how much I hate automatics.

I've thought about selling the wagon when the weather warms up and getting a 6MT E92, but I love the shape of the wagon. After thinking about this a lot (read: too much), an ambitious thought popped into my head: what if I were to buy a wrecked E60 550i6 and swap over the subframes, suspension, brakes, and drivetrain? It would certainly be a huge project and I've never done one that big, but I figure the cars are quite similar so it probably would be a good place to start (maybe easier than my dream of swapping an S54 into my E39 530i5).

Mechanically, I don't see why everything shouldn't fit. The electrical side of things would obviously be more complicated, and I'd need to do a bunch of research before diving in. Mostly I'd be concerned about the instrument cluster, air suspension, etc, as being different from a sedan and potentially causing problems.

I'd buy an N54 E61, but I don't want automatic and I don't want another needy N54. If it wasn't my main car, I'd have the N54 (although probably would get an E36 M3 or Porsche Boxster instead). Also, I think right around 350hp would be ideal, as my 335i was tuned and probably was a bit too powerful for my skill level (I've done some performance driving ed, but would like to do more). If I did the V8 swap, I'd be able to replace all the gaskets in an N62 while the engine was out, as well as preventatively fix the coolant pipes and potentially even valve stem seals. My E61 isn't the cleanest car for the swap (a few dings, paint chips, etc), but at school I park on the street and wouldn't want to park a pristine car here anyway.

Interested to hear peoples' reactions–if it sounds absolutely ridiculous, I'd like to know. Not going for huge power here, but more for handling, RWD, manual, and character. Would be a very cool rig, although costs could be prohibitive. I'd plan on doing it this June, and could drive my E39 when the wagon is under the knife. I recently learned that BMW produced an E61 550iT in Europe, which makes me think the swap may not be terribly complicated. Unfortunately, I understand mechanics more than electronics, and need to to research on swapping ECUs, the wiring harness, and how the instrument cluster would react. The ignition/immobilizer also concerns me–do I need to use parts from the donor car, or can I keep the current system? Also, is there any reason I should look for an '08 M-sport 550i donor (suspension wise, etc?) over a cheaper '07? I know the M-sports have active suspension, but I don't think that would be necessary for me. I'm not sure whether or not I want to do M-sport aero, although that could happen later. I am relatively new to the E6X platform, so if there is anything I should know specifically, I'd love to hear it!

Thanks for the feedback!

Here's the wagon as it sits at 184k miles:

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The previous owners really neglected it, and while it's a lot better now than when I bought it, there are still a few issues to sort out and generally the drivetrain feels a bit lazy at the moment.