Lightweight e30, have platform/engine ideas, leaning 318is/N52… talk me out of it

[88Sedan]

Just my own opinion here but I like the idea of an aluminum block m54 or m52tub28 from a z3 but those are getting hard to find and I think US tub28 blocks were nikisil bores making rebuilding a non option or harder. IMO the power level is 'just right' especially with a cam change and tune. While most delete AC I have seen at least a few cars make it work. I imagine the weight bias would be pretty close to 50/50.

[OSAH racing]

You need to drive a 24v swapped e30 before you call the handling compromised.

I have, I did, I have owned them and a 24 valve is noticeably slower at turn in compared to a 4 cylinder engine in the e30. I am not saying 24 valve motor's suck. I liked my enough. I am saying if handling is what your after the F20-C is a great choice.

[uturn]

The increase in power you want will require rear fender work to get wider tires to handle it. Money, work and effort will not be worth it imho.

I think what you want is the Z3 clown shoe.

[amcp]

You need to drive a 24v swapped e30 before you call the handling compromised.

[OSAH racing]

I also am after a great driving experience and my preference is handling over power. I have had several old cars ( I am a young 62) and agree air cooled Porsches are too much money to play with. I have had a few different e30's and My experience is the 4 cylinder engine placement is optimal. In General cornering speeds are higher. Your right the M42 needs more power, an oil cooler and a lot of custom work to yield 200 HP. I am in the process of building something similar as you in regards to use. Mostly a street canyon car with a few AX and track days for fun. I am sticking with the M20 because I could not find enough reliable information about K - swap E30's. I do believe the best motor/transmission if your up for the cost is the F20 from the S2000.

My M20b25 decision is based on several points. 1: Spec e30 cars are pretty darn fast with a skilled driver
2: Lots of support with from the aftermarket for engines, brakes and suspension parts.
3: Stock oil cooler, LSD with many choices
4: Durable
5: Cost
My conclusion is the e30 will always have a few compromises built into it with my budget to play. I have had an 97 e36M3, 91 slick top 318i S52, 91 318i M42 for the track and currently a 90 325i. I prefer the handling of the 4 cylinder car, the sound of the M20 car and the power of the S52. Good luck and keep us informed these are fun cars to drive.

[Maxhouse97]

Hi,

New to the e30 community, coming from a couple of different automotive experiences (Miata, GTI, 911, Cayman, E46 M3 - last two I still own). Looking to get into a e30 for these reasons:

• I like small, lightweight cars. Drive a slow-ish car fast kind of thing. Go-kart, short gears, a “you make a control input and the car moves immediately” dynamic.
• I’m a NA engine geek, high-reving but decent torque lover (S54 perfect combo). Prioritize engine responsiveness (fast reving, sound, lack of vibration) over outright power.
• I have a European preference, had good experience with BMW (E46, Z3). Also like the 80s nostalgia. Was thinking of going back to aircooled 911s but prices are ridiculous. And so are e30 M3s.
• Looking for a street car, canyon carver, OEM + build/look, no track planned but would want “track in a pinch” options (E46 is my track car). I’m approaching 50 so want a car with full A/C, amenities, etc.
• I can do some of my own mechanical work (have pulled engines/trans and swapped suspensions) but don’t have a ton of time and don’t do well with electronics/computers so in general prefer OEM like kits/simplicity. Willing to spend some money to get there.
• I don’t want another Miata

As I started to research e30s, I quickly gravitated to the 318is for its ultimate lightweight package. Balanced handling due to low weight over the front end, etc. However as I’m also an engine guy, I don’t think the M42 will cut it. I read the 2019 Grassroots Motorsports article where they spent 8k rebuilding the motor and still seemed to get a meh result. Therefore I quickly resolved to look into good engine swaps that would add some power (and torque for the street) yet keep the lightweight feel.

Here are the options as have I gathered them (it’s funny how detailed some of the swap forum threads get when you’re looking for high level thoughts/details):

• K24/20: this is where I started, I have been intrigued by this motor for some time as it’s a model of NA, high/reving power. I spoke to K-tune and they can do a complete swap with labor. Upsides: lightweight with power torque, amazing aftermarket, reliable, everywhere. Downsides: does not keep it BMW, might be a money pit that would not have residual value in the eyes of e30 enthusiasts, second order vibrations from the long stroke 2.4 motor (K-tune kit gets rid of the balance shafts).
• Stroked M42 + ITBs - then went this way, why not stick with what it came with? Upsides: no swap needed, keeps the lightweight part but adds the motorsports feel. Downsides: $$, don’t think the motor was designed with this in mind (S42 notwithstanding), Grassroots article really turned me off. Very little support. Must be a reason very few have done this.
• S50/52/54 motor - came here next. I love ITBs and M engines. Upsides: pedigree, motorsports feel, great power/torque, good support. Downsides: super heavy, violates requirement number 1 and compromises handling. Expensive. Only thing I’ve thought about is putting a S54 in if I have to sell my E46, but that’s not in the cards now. Feel the S54 would make it into a very different car than the 318is, more AC cobra/muscle car.
• M54 - progressed to this motor. Stout, forged crank, tried and true. They are being raced all the time in Spec E46. E46 330 ZHP is a car I like. Upsides: AL block cuts down on weight (according to a post with pictures of scales, 70lbs lighter than an M20), has been done many times, relatively modern motor. Seem to sound good. Downsides: don’t rev very high or fast, not motorsports like? More torque focused than a balanced torque/upper end power motor. Still heavy compared to the M42. Seems to be the 2000/2010s option, but most now going S54 or something else.
• N52 - where I am now. From everything I can ascertain, this gets me the closest to where I want to be. Upsides: lowest weight BMW Six (hard to tell how close to a M42 weight), inline 6 naturally balanced. Great power/torque for NA, pinnacle of BMW NA engines before turbo took over. 7k or higher redline. Seems to be the “in” swap now, which means many of the smart people who know this platform better than me have landed on this. Very cheap motors. Valvetronic provides quasi-ITB like performance (RPD trumpet kit looks very intriguing with even more weight savings). Right amount of power (I don’t need more than 250 hp). Downsides: too new/clinical, lack of character & sound? Lack (or nascent but developing) support. Too hard to integrate electronics into a 1980s car. No plug and play kit. I have to admit some of these are unconfirmed, mostly concerns that could be proven wrong as I do more research.

Now I have one admission to make - I HAVE NEVER DRIVEN AN E30. Up to now I have exclusively spent time with Porsche/E46 people. I have based all of the above on research/discussions with folks at C&C (I had an in depth one with a guy who swapped in a Pontiac Solstice motor). So I could be completely off base. But honestly I think the world is done making small, lightweight cars that are not Miata’s, so I think the e30 will hit the mark. I love my E46 and I know it was derived from the e30 (strut front, independent rear). And yes I plan to drive them once I can find a way to.

What are your thoughts? Is the N52 the right option for me?

And is the 318is the right starting point for a lightweight car? Feel I get can a real nice one for 10-15k, and then collect parts/build it over the next couple of years (I don’t want to start with a project car). Latest built model would help mitigate old car issues (although I really like pop out rear windows). Or would you suggest another e30 model?

Will be posting in different forums to get both platform/swap feedback. Thanks for reading this far.