Help me choose a direction for my project

I'm at a crossroads with my e36 m3 project. The suspension rebuild will be done in the next month or so, which means it'll be time to start on the engine. 

At 140k miles, the s50 is starting to feel kinda tired. As I see it, I've got 3, maybe 4 options. Absolute power isn't the goal, although a little more wouldn't be the worst thing in the world. I probably won't be tracking the car, at least not anytime soon. With work and other life changes, I just don't have the time. I've never done a swap, or even any in depth engine work, but it's always been a goal of mine to do so. 

Option 1: NA rebuild of the s50-maybe cams/valvetrain upgrades?

Pros: Easy, cheap, and pretty well documented. 
Cons: Not exactly the most exciting option. A lot of work for a relatively small power gain

Option 2: s50 rebuild for boost-turbo/supercharger?

Pros: more power, some cool noises
Cons: heat management issues, more complexity, less induction noise

Option 3: s54 swap

Pros: more power, awesome induction noise, well documented, I'd end up with the car I'd ultimately like to own
Cons: cost-most say to budget $7.5-10k for a swap, complexity-valve adjustments, higher consumable costs

Bonus Option 4: sell the car, buy an e46 m3
-Life changes have me considering a change of platform. Everyone knows how E36 M3ty the e36 interiors are, and mine's no exception. I'd hope to get around $9-10k for my m3 if I were to sell it, and could probably convince SWMBO to let me add money on top of that to find a decent e46. 

Pros: the relative easy button, higher quality interior pieces, looks cool, SMG to manual conversions are well documented now
Cons: I'm weird and prefer the looks of the e36 m3, I'd likely only be able to afford an SMG m3 after selling my e36, starting over on a new chassis is kinda annoying

Any guidance? 

From the sounds of it you still like the car, but the engine is letting it down a bit. It seems like swapping to an E46 would be a mistake, since you don't prefer the looks. I don't think you are weird for liking the E36 over the E46, I prefer them as well and even prefer the E34 over the much loved E39.

If you plan to keep the car, I would go with option #1. Personally, I want my cars to work with an OEM level of reliability or greater, and I think the other options add more variables for compilation. Adding forced induction to a car that was never designed for it usually results in a lot more headaches than you initially anticipate. It's great if you really want or need the power for your application, but it really doesn't sound like that's the case for you. The S54 is a great engine, but if you are going to go through the expense of the swap I would think a Euro S50 would be the better bet, more straight forward, and probably add and retain more value. If you care about that kind of thing.

I know E36 interiors aren't great, but I think there are a few things you could do to improve it if you were looking to keep the car long term. Find a nice set of Recaros recover them with some M Rain or M Hurricane fabric. Do the door card centers as well, and maybe do the rear seats the same or a delete if you have a coupe and no need for them. Maybe do an alcantara headliner?  If your dislike for the interior goes beyond that, then I honestly think you might want to look outside the BMW pond for a replacement.

The E46 is great, but if you prefer the looks of the E36 I think you'll always miss that when looking at the E46 that replaced it. In that case I would say look into a Boxster/Cayman depending on your preference. 986's aren't a huge improvement on the interior front, but 987's are really nice.

Just some food for thought.

LS3

it had to be said

For the same price as a S54 swap or a boosted setup you could also K-swap and boost to get some cool induction noises, turbo whistle, and blowoff valve noises. 

Or you can go the GM 4.8, 5.3, LSx route, again with similar pricing. 

S54s are cool and are great swap options to keep in the family but damn they are expensive. 

I'm of the mind that you should keep the experience coherent but turn it up a little. I say rebuild with mild upgrades. OEM reliability, more tractable and I think it will be the most enjoyable over the long term. Maybe drop a shorter rear end in too. 
Im a little biased in that I grew up in an E36 and I think they're a brilliant blend of usable performance and character. A 95 M3 is on my short list of lottery purchases. 
 

Also, just curious, why are you chasing a rebuild? My M50 was still solid at 230k and I ran it hard. These engines are pretty solid if they have been taken care of. 

Option 5: continue to flog the dogE36 M3 out of the s50 for another 60k miles. These bottom ends do not get "tired" as they are extremely robust and a head refresh is a weekend job at most if your compression is down a bit. Slap a set of reground cams, an intake, ebay stainless longtube headers, and an epic tune on it if you must do something. 

If you want a project, slap an S54 in it. 7-10k seems in the ballpark if you are addressing vanos and rod bearings, but guessing you could budget swap it for 4-5k with a little effort. Would be an absolute blast and keep the same feel (5 speed can remain) of a peppy rev happy motor with the benefits of boost and zero downsides. Can also sell the s50 for 1800 bucks easy.

What are your intended uses for this car? Track events frequently?

Look at it without constraint of reasonable thoughts, what do you want to do, then shut up and start cutting. This whole thing is for happiness man. Make your dream come true, dont crowd source your art. 

All these options require time/money. How much time and money do you have? 

I find time is the biggest hurdle for me in these projects. If you have a lot of time, do the thing you desire the most. If you have less time, make the “rational” decision, meaning what will require the least time.

FWIW I owned an S52-powered M3 for years and rarely felt like it needed more power. The suspension upgrades were far more important to me. Once the car had good spring rates, camber, and shocks, it seemed silly to change the engine, and I never did. Maybe drive it for a while with the new suspension and see what emerges. 

In reply to Olemiss540 :

The PO sucked at maintaining the car. I've been catching up on deferred maintenance the entire time I've owned it. I test drove it and fell in love with the car and that made me overlook a lot of its flaws. 
it's already got a full exhaust (headers, midpipe, and catback), intake, tune, and a 3.38 LSD from an auto car. 
I originally bought it as a track car, but then life got in the way. No track time for me for another few years at least. I just want something fun to drive for now, and building/rebuilding/swapping an engine is something I've always wanted to do, but haven't actually done yet. 

In reply to DirtyBird222 :

I definitely agree on the cost, and I'd thought about an LS swap, but the price of anything LS is insane around here, and with the added cost of the trans and driveshaft, I wouldn't be saving too much money. 
I've never really been a purist, but I do kinda feel like an i6 is the right engine for the car. Just kinda suits its character. 

Option 5 is good if possible. 
 

If time is the constraint I would absolutely recommend the path of least work and most enjoyment. Stalled projects are unnecessary stress and it's not like a stock M3 is a boring car. Do the minimum to make it safe and reliable and send it....Sideways with glorious straight six noises ideally. 

In reply to MTechnically (Forum Supporter) :

I'm definitely with you on the e34! An e34 m5 is a bucket list car for me. I love the s38 lol

As far as my car goes, it's already not much of a collector piece, in my opinion at least. I've been playing catch up with all of the deferred maintenance from the PO. 
I'm actually in the middle of pulling the headliner at the moment. And the door cards and rear panels are in need of attention.
The car came with some Recaro reclining seats that I traded for some newly reupholstered Vaders, but 10k miles later, I've learned that I'm really not a fan lol

That being said, the euro s50 would be cool, but I was worried about parts availability vs the s54. Maybe it's not so bad?

its just a nonstop learning experience. This is my first real in depth project car

If time and money constraints are keeping you from track days, then I'm not sure how an S54 swap is going to better in that regard (especially financially).   Boost can be quicker/cheaper, but it's also a potential rabbit hole of parts, tinkering, and aforementioned unexpected headaches.  However, you could easily prove me wrong with challenge-levels of ingenuity.  I guess I'm also in the camp of restomod the S50 or consider a different car. 

Edit - or Option 5.  I like that option.

Carbon (Forum Supporter) said:

Look at it without constraint of reasonable thoughts, what do you want to do, then shut up and start cutting. This whole thing is for happiness man. Make your dream come true, dont crowd source your art. 

Crowd sourcing art is half of the forum posts here!

Option 5.1 - use all that time and money you have to do rebuilds and/or swaps and spend it on a half-cage, harness, seat, helmet, and get out to the damn track. 

Matt B (Forum Supporter) said:

Option 5.1 - use all that time and money you have to do rebuilds and/or swaps and spend it on a half-cage, harness, seat, helmet, and get out to the damn track. 

I'm with Matt. I've got an S52 swapped E36 sedan with headers, exhaust, suspension, M3 brakes and an E46 M3 that is nearly stock. I prefer the E36 and my investments are all going to be in adding lightness and safety and track time. My interior is in damn fine shape so as I strip it out I'll be making some folks really happy when my dove Vader seats go up for sale and can be used by someone who is chasing an interior restoration.

Well, at the very least, y'all have convinced me to keep the e36. And I'm definitely leaning towards a top end rebuild on the s50. My heart still says s54, but that can wait until after the s50 is toast 
Thanks for listening. Car culture in my area (rural central Ohio) is mostly brodozer diesels, so it's nice to have a place to talk through my ideas

After putting 50k on my S52 E36 I drove a few E46 M3s. It's just not the same. The extra power and the high revvs are really nice, but everything else just doesn't feel right. Depending on power goals, there's also a vortech supercharger for just a little boost without all the exhaust and plumbing issues of the turbo.

If you plan to track it, please dont chase the same forced induction rabbit hole I did with the various supercharger configurations.....

Yeah, boost is by far the least appealing of the options, but I was keeping my mind open in case any of you guys had any rave reviews for a specific turbo/supercharger kit lol