Should I swap?

[varg]

Depends on what you want out of it performance wise. If the car is being brought to show quality it makes the most sense to have a squeaky clean M20 under the hood, whether stock looking, ITB equipped or turbocharged. The only M5X swaps that makes sense are the aluminum 2.8 or an M54B30. Everything else is extra weight gain for nothing since it's downright easy to make the meager M50/52 power with an M20 build. Plus M5Xs are so ugly... I suppose a case could be made for an M50 swap if you want to make big turbo power, but people have done that on M20s too (Nisse Järnet making like 700whp with an M20 comes to mind).

A 2.8 Stroker M20 is M52B28 crank, 130mm M20 rods (eta or aftermarket), M20B25 pistons, deck brought down to suit and give a good compression ratio, and a spacer on the crank snout. There's some machine work involved, taking the skirts on the pistons and the weights on the crankshaft down, but it's an easy recipe for 200hp+ depending on how much you want to spend on a head, cam and induction system. It's a tried and true recipe and it keeps the handsome M20 under your hood instead of those awful plastic valve covers on M5X and S50/52. If you want some fast a turbo M20 is the way to go, especially since you aren't going to be tracking a show ready car; it's too risky.
2.8 examples: https://www.r3vlimited.com/board/for...i-reincarnated

http://www.msportster.co.uk/question/m20b28-build-in-full/

https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/210196-bullet-ride-s-2-8l-stroker-project-updated-dyno-plot-pg-6

There are lots of them and it's easy to find them if you search with google by using the site:r3vlimited.com in your search, vs the forum's search engine.

[GarbageCanE30]

swap it. s52 or s54 if you got money. wish i went that route

How is the s54 compared to earlier s series motors? I've had a few friends who have had endless issues with their e46 m3s so it scared me a bit. Also I've yet to look into what that swap entails but I'm assuming it's a bit more in depth then the earlier engines. Wish I could do an s38 and keep the era the same... That's a badass motor but would be unspeakably expensive :(

[GarbageCanE30]

I think it's pointless to swap a b25 for a m5x. Personally I'd keep the original engine that you know is good and build an eta stroker with some off the shelf pistons. Drop everything off a machine shop and I bet that what it would cost to have them professionally assemble the short block and do a valve job on the head is comparable to the price of a healthy s5x and all the parts you need to hunt down for a complete swap (transmission, driveshaft, oil pan, exhaust, brake booster, etc). There's no dealing with the brake booster clearance or exhaust fabrication, it just bolts back in place and you're good to go. Not as powerful as a s5x but so what.

Price is definitely less of the issue, I'm moreso looking for reliability and something that will be desired on the second hand market should I sell it after building it. I intend to put a lot in the car and I firmly believe the quality of the engine build should match or exceed the quality of the exterior. The m20 has been a breeze for me to work on which is nice as well but mine is a bit beat up and definitely needs the refresh despite having only 13x,xxx miles on it. Do you know of any links on here for an ETA stroker build? Ive reviewed a few of the swap threads for the m/s52 and it really doesn't seem all that challenging. Most challenging bit seems to be finding the parts to do it right.

[E30 Wagen]

I think it's pointless to swap a b25 for a m5x. Personally I'd keep the original engine that you know is good and build an eta stroker with some off the shelf pistons. Drop everything off a machine shop and I bet that what it would cost to have them professionally assemble the short block and do a valve job on the head is comparable to the price of a healthy s5x and all the parts you need to hunt down for a complete swap (transmission, driveshaft, oil pan, exhaust, brake booster, etc). There's no dealing with the brake booster clearance or exhaust fabrication, it just bolts back in place and you're good to go. Not as powerful as a s5x but so what.

[Metallated]

It's definitely been done a lot, but S or even M52 is I think the best bang for your buck. The swap is so easy and well documented, and can be done fairly cheap. You also get OBD2, and a nice boost to power.

[Zambuzan]

... or be a lil different and wait a few months till k24 swap kits come into the market. Few companies are working on them rn.
Stock k24 makes good power for such a small power-plant, and potentially keep e30-everything from the bellhouse to the diff.

[efficient]

swap it. s52 or s54 if you got money. wish i went that route

[GarbageCanE30]

Hey guys, new to the forum and e30 world. I recently acquired an 89' 325is in zinno and am trying to refresh it and take it to show-worthy condition. I currently have the m20 out and was on the fence as to how to proceed. I'm definitely wanting to make more power over stock whether that means stroking the m20, turboing it, or doing a m50/52 or s50/52 swap. What would you do and why? Obviously this is a matter of opinion, but I'm having a hard time deciding what direction to go in. Id probably take into account the difficulty of the build as I'm new to auto projects of this magnitude but tend to get comfortable and learn quickly. Thanks for reading and looking forward to hearing your opinions.