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

[OSAH racing]

The Value is in the experience. Its always worth the cost if you use it.

[82eye]

Yeah, that's the big problem. If certain parts could be reproduced or substituted then I'm still in the m4x 88mm stroker camp though, just seems easier.

it's a bit sad as bmw has been noted for supporting the older platforms. that is fading for a lot of marques, everything ages out of being financially lucrative.

If you're in the market for a nice $10-15k example then indeed you may discover it's plenty fun to drive and the hassle of an engine swap isn't worth it, especially if it's in survivor condition where extensive mods may actually hurt the residual value. Same could be said for a nice 325i. If you can find a nice 325i then that's obviously more power out of the box with straight forward upgrade paths, and it's still going to feel light compared to a newer platform.

at some point i had to make the call whether my car was going modded or clean. you never see them here, so there was an argument for a clean stock example, but i don't consider it all that rare or special. it's been painted once already, and it's failing. it's getting paint again in the spring. but it won't be showroom either.

since i wanted a driver and it's no collector the decision to have some fun and mod it was easy. i'll never make the money back, but i built most of the drive train with my dad, and i'll never replace that experience.
long term the car will never be worth what it could be as a restored stock example. i've completely capped the value to any future owner. but who cares.

When it comes to m5x or s5x swaps I'd rather just get an e36 at that point. But the 128i remains a very compelling option as a modern 318is, of course not as light but certainly small and nimble. Get yourself a nice one or two owner slick top 6 speed example now, guaranteed future classic.

need another job first lol.

[82eye]

wow .. weighs out identical to the m42

[adam.nonis]

K24 w/ZF: 427lbs




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[82eye]

the 128i remains a very compelling option as a modern 318is, of course not as light but certainly small and nimble. Get yourself a nice one or two owner slick top 6 speed example now, guaranteed future classic.

i watch the locals daily looking to see if a manual e82 slips through. i truly believe it's the spiritual successor to an e30.

[E30 Wagen]

isn't parts availability the issue with the m42 now? it seems to get cited more and more as the reason for a swap option

Yeah, that's the big problem. If certain parts could be reproduced or substituted then I'm still in the m4x 88mm stroker camp though, just seems easier.

If you're in the market for a nice $10-15k example then indeed you may discover it's plenty fun to drive and the hassle of an engine swap isn't worth it, especially if it's in survivor condition where extensive mods may actually hurt the residual value. Same could be said for a nice 325i. If you can find a nice 325i then that's obviously more power out of the box with straight forward upgrade paths, and it's still going to feel light compared to a newer platform. When it comes to m5x or s5x swaps I'd rather just get an e36 at that point. But the 128i remains a very compelling option as a modern 318is, of course not as light but certainly small and nimble. Get yourself a nice one or two owner slick top 6 speed example now, guaranteed future classic.

[adam.nonis]

Just like posted on the other thread:
M20 w/G260: 497lbs



M54 w/G260: 475lbs



N52 w/GS6-17: 458lbs



M42/Manual Trans: 427lbs




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[82eye]

Yes agree Honda power is best, but after considering it more I’m turned off by the vibration and non-BMW lineage. If it were more of a track car this is where I would go.

all things equal i wouldn't turn my nose up at a k swap personally. especially a nice clean one. power potential, parts availability, and cost factor all make it a possibly attainable dream. s5x will always be the purist swap imo, but you pretty much need to be a youtube star to attain it now, or rich enough to buy a few youtube stars ...
don't think i'll ever have the $$ for that. lol.


edit: also the weight factor is decent on the k. it is a tall engine though.

if you get any e30 both the m20 and m42 are good for some cheap fun while you decide on which way to go. i love my iron lung of an m20 lol .. some simple mods really help and change the car.

[Maxhouse97]

Thanks for all of the responses, Varg yours especially with all the detail. Great community here. Seems to confirm a lot of my research.

Yes agree Honda power is best, but after considering it more I’m turned off by the vibration and non-BMW lineage. If it were more of a track car this is where I would go.

WRT to the M42, GRM article likened their built 318is to a 1.6L Miata … that was harsh criticism. However agree this is in line with the slow car fast thought, and respect everyone who owns these.

I do like handling over power, but I also like straight 6s for their pedigree, sound, and lack of vibration. I was not willing to pay the weight “price” when it was 70-90 lbs (M20 over 42). But as far as I can tell an N52 cuts into more than half of that, so I think it’s worth it. Hoveringuy’s response on the N52 subforum sums it up perfectly. I think we are at the start of a number of N52 swaps as they catch on.

As far as platforms, another reason I was thinking of getting a 318is (beyond the weight and slick top potential) is it lets me try before I buy. Maybe I’ll find the M42 ok enough. Any other reasons to start with a 325 over 318?

[varg]

isn't parts availability the issue with the m42 now? it seems to get cited more and more as the reason for a swap option

Harmonic balancers are NLA according to a turbo M42 guy I sold mine to. Timing sprockets went NLA after I did my M20 swap so years ago now. I'm not sure about other parts but those are both wear items with the newest M42s being almost 30 years old. If NA performance is a goal a stroll through M42club to see the results of their builds is reason enough to swap.

[82eye]

Call me a snooty purist but I honestly couldn't bring myself to swap a nice "survivor" 318is with anything but a stroked m42. .

isn't parts availability the issue with the m42 now? it seems to get cited more and more as the reason for a swap option

[E30 Wagen]

Call me a snooty purist but I honestly couldn't bring myself to swap a nice "survivor" 318is with anything but a stroked m42. The balance and handling with the m42 up front felt perfect to me, and after seeing so many get swapped it makes me happy to see that engine still getting some love. Concerning actual chassis weight, the only real advantage I see to starting with a 318is is if you can find a slicktop, which along with the 318i sedan was the only e30 offered as such in the US. Since slicktops are rare and if you're leaning toward an engine swap then you might as well include all the 325 models in your search. You get a larger exhaust opening in the rear of 88+ 325 models (just a single cutout on the 318is), which might be convenient depending on what engine you go with. M42 cars also have a big ignition coil mounting bracket that I always thought looks a bit awkward sitting bare after a different engine is swapped in, but that's just me. Sure, other engines might make more power, but I've always really wanted to do a m4x stroker, itbs with a carbon box, maybe even a carbon valve cover, electric fan, no AC, no PS, carbon hood, carbon trunk, lightweight glass, lightweight seats...

If I could find a slicktop e36 then I'd basically want to do the same style of build because i kinda like e36s more now... Or I'd build a 3L out of the Z3 alu block.

Other car to consider would be a e82 128i.

edit: also, the stroker that GRM built only used the m44 crank, not the 88mm m47 crank.

[packratbimmer]

K20 + a six speed

[varg]

K24/20: Best 4 cylinder option. Light, available, make good power NA and great power turbo. Still a 4cyl with 4cyl sound and vibration.
Stroked M42 + ITBs: You'll spend a ton of money just to make K20A eco power and be left with less low end. Price out a set of cams + head work + ITBs.
S50/52/54: They are definitely heavier, M50s are something like 50lb heavier than M20s, M20+transmission is 70lb heavier than M42+transmission. S52s have a heavier crank than an M50 (I wish I had weighed my B30 crank and B25 crank side by side but oh well), S54s are quite heavy indeed and also long. So you'd be gaining over 100lbs and most of it up front. It definitely will change the character of the car. My M20 swap felt different from my M42, but I much prefer the M20 for everything else. I bet a stock S52 weights almost exactly as much as a turbo M20.
M54: Good option. Pretty light, less than an M20, lots of low end torque, you're correct in that they don't rev high and it's not worth trying to make one rev high. 24V cams are expensive, stock falls flat before 6,500rpm, crank harmonics are supposedly an issue with the B30 crank (same part as the S52 crank btw), with plenty of forum lore from people having issues after beating the hell out of M54s and S52s at high rpm. I haven't driven an M54 E30, but M54 cars benefit from the low end torque, it makes them more fun than if they were gutless and had to rev more to get to the torque like a non Vanos M50
N52: Watching the swaps, these are a better option in every way than an M54, just harder to pull off. They're supposedly lighter, more tolerant of revving. Lack of sound and clinical? With some "ITBs" (really just trumpets on the open unthrottled ports using valvetronic) I have heard sonorous induction noise from an N52. Like all BMW I6s, the exhaust sounds like crap without a turbo to calm it or a well designed equal length system to keep it from just being a buzzy mess. Quieter is better. If I were doing an NA I6 swap in an E30 today, I would probably go N52 and try out the velocity stack setup and a quiet exhaust. We're talking more power and torque than an S52 and less weight than an M20, which sounds like fun.

I think it's best to make an E30 an E30 and appreciate it for what it is. They have limitations. Mine is pretty aggressively modified with coilovers, stiff bushings, pretty extreme tires, then I get in my FD and even without pushing it hard I see that with of those mods my E30 is still an E30, not a sports car. It's a flexible chassis, it has disappointing steering stock and has good steering with a Z3 rack like mine, though it tramlines a lot with the tires I have on it.

For objective performance and handling, there's no better option than a K series IMO. A 318is is in the 2600lb range weight wise, with a medium case LSD and a K series you probably gain next to no weight but could make S52 power with a decent NA build. For everything else, like performance on a budget and E30 character, turbo M20 is unmatched. Bolt in swap, lots of torque and power. All of those NA 24V swaps people did over the years seem like a waste when 300whp worth of turbo on an M20 and makes S54 power, more torque, and at less weight, cost, and difficulty fitting everything in. I, for one, having gone from turbo 4 to turbo 6 love how smooth an M20 feels in comparison.

[hoveringuy]

I posted my N52 thoughts on this question in the N52 engine sub-section. TLDR; DOHC goodness without the fat.