In a garage, even if you have the tools, it is a hard 10 on a scale of 1-10 of difficulty. I would just take the M3 and drive it...No point in putting it in a sedan body other than looks. I have seen S54 swapped sedans and love them, but the hours of labor it takes is lunacy.

 

What's so hard about it? Honestly curious. Everything should bolt right up except for the exhaust. No fabrication required.

There are so many little parts needed for a swap that a donor car can be cheaper and much less of a headache in the long run. That's the way I plan to go if/when I do an S54 swap into mine.

 

Just buy used engine, transmission, and rear end, instead of butchering a good M3. It is very hard and costly!

 

Hmm, yeah, talk us through why it's a 10. I wouldn't say it's 'easy' like changing an air filter, but I'm trying to imagine.

If you stick an M3 rear subframe into a sedan, do you have to have et60 wheels no wider than 5"?

I would have guessed an '8' if you wanted a sleeper, and reserved '10' for grafting fenders, etc from the M coupe/vert onto a sedan body.

t
would build the sleeper E34 touring, but yeah, that'd be more than an 8.

 

M3 trailing arms and subframe have the same overall width as the non-M. M3 gets its extra track width entirely through the fender flares. So he should still be able to fit any wheels that fit fine on a non-M.

Front is tougher if you do the full M3 suspension conversion. The front track is like 20mm wider.

The basic engine swap is not much tougher than swapping in another M54. Minor fabrication needed for peripherals like the expansion tank mounts and such. Engine itself more or less slots right in.

 

not sure what your level of wrenching is?
*i have not done this personally*

there isn’t a lot of fabricating like doing other non-E46 swaps, the chassis is basically the same. but it’s not without having knowledge to do since you’ll need to swap harness and other things as well. having your cousins tools and engine hoist isn’t like having a lift and full array of shop tools at your disposal. muffler adapting, coding and probably reinforcing as well.

there’s several S54 swaps on the forum posted. one of the first was MITe46.
https://forum.e46fanatics.com/showthread.php?t=176943&page=2

but honestly having done other engine builds and swaps it all depends on information out there. I usually have concerns about another’s capabilities. The broad saying, “if you have to ask, it’s probably beyond you” comes to mind. meaning you should have an anticipated idea already before asking. having already figured basics like fuel management and wiring.

But all of us ”wrenchers” had our first engine swap at one time. So we all started somewhere I suppose. I would not suggest it for a novice though.

 

I have done this swap and can probably help you navigate some of the obstacles that you'll encounter. For my project, I started with a 2003 330i sedan. I pulled the engine and transmission myself, originally with the intention of reinstalling the M54 engine with enhancements that I estimated would yield an extra 20-30 HP. That was a first for me with a BMW (my only prior engine removal and rebuilding experience was with a 1969 VW bus). That was so much work (made more difficult, I eventually learned, by broken engine mounts) that by the time I completed that first stage, I was easily persuaded to drop the idea of putting the M54 engine back in ("Are you crazy!? After going through all of that, you're going to reinstall the same engine?").

And so, a simple 330i sedan enhancement project morphed into a S54 engine swap. And once I accepted that line of thinking, the project soon snowballed from there into a complete M3 conversion. At that point, aware that I lacked the level of experience necessary to finish a project like this (in a reasonable amount of time), I took the 330i chassis to professionals to complete the transformation: Premier Restorations in Clifton, NJ for bodywork, paint, and interior; and Autocouture Motoring in Fair Lawn, NJ for everything mechanical. The mechanic assigned to my project took notes, as needed, regarding every issue encountered that was not just a straightforward swap. I think I am aware of most of the bigger issues, at least in general terms; where specific details are needed, I might be well enough informed to point you in the right direction to find the information you need.

Of course, other members on this forum with more knowledge and experience than I are available and willing to help. One issue in particular that you'll have to grapple with are pinout changes that are required to make a M3 MSS54 DME (ECU) work with your 330i wiring harness. Of course, an S54 engine wiring harness was installed, but this swap alone - along with the ECU swap - will not suffice. There will be still be issues related to differing pin assignments in the 330i and M3 chassis. Without these changes, the engine will not even start. Autocouture Motoring consulted an outside specialist (Kassel Performance, in York, PA) to sort out this problem. Good luck with your project if you decide to take the plunge!

My car received a complete color change and several enhancements (bodywork, interior, and mechanical), and the project is now two years in gestation. It is at a detailer now getting finishing touches. But soon it will be ready, at which point I will post more extensively about this experience.

P.S. I would like to post images, but I am baffled by the pop-up window that asks for the URL for the image. Can someone help, please? My photos are stored on an internal drive, but not on any webpage. How do you post photos to this forum?

 

Definitely drop the s54 in, if you have 2 complete cars then the swap is easy. And there is the bonus of killing a convertible

 

Photos of my 2003 330i sedan to M3 conversion.

 

I don't see why some people are making the swap seem impossible, especially if the donor car is right there, that actually makes it much easier. It's not that difficult if you're mechanically inclined and did your research.

I just finished my s54 swap last month. It took me a week only because I was waiting on parts to ship and replacing the rod bearings, rebuilding the vanos, etc. If it weren't for the wait time in parts I couldve finished earlier.

I never did an s54 swap before but I did about a months worth of extensive research before diving in, that's also how I learned to code it as well.

OP, if you need some pointers PM me.

 

This E46 M3 sedan project is my favo.

JEPPE: E46 M3 SMG sedan prosjekt

Dette er prosjekt tråden til min E46 M3 sedan. Orginal tråden fra byggestart til slutt ligger på e46fanatics.com og går over 70 sider med spørsmål/svar og kommentarer: E46fanatics.com Har kopiert det jeg har skrevet i den tråden over hit. Donor bilen var en helt strøken 2002 BMW M3 SMG som hadde ...

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