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Old 02-18-2019, 04:19 PM   #1
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Survey of swap difficulty, updated for 2019 knowledge & parts availability

Hi all

I've done a lot of reading here and elsewhere about the various 24v swaps but it seems that technology (wiring/flashing) as well as parts availability (ie - can now buy parts that used to be custom such as trans mounts, ever changing availability of header that fit) have come a long way. Many searches result in outdated info.

I would like to ask the community's input on the relative difficulty of the most popular swaps... OBDI/II


My personal interest, which I think others share, is an 'improved daily' swap that doesn't add weight but does add power, efficiency, torque spread. For this reason I lean to the later alum block motors but am finding it hard to ascertain the difference in effort, cost, parts sourcing, etc between M52 alum, M52TU and M54. Any knowledge shared here would be greatly appreciated. Much like some other threads it would be interesting to know how you handled

Donor Motor - year, model, cost
ECU / Harness - year, model or standalone
ECU Elements Deleted / Flashed
Harness Adapter - DIY, purchased, from who
CAN functionality?
Headers - and comment on fit
Brake Booster - year, model
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Old 02-19-2019, 10:14 AM   #2
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I honestly think we're reaching the end of the viability of the M/S5x swaps. For an e30 any of these engines require either an increasingly rare e34 oil pan that was only made as a stopgap for three years and ended production almost 30 years ago OR an extensively modified pan AND crossmember AND swaybar relocation.

Even the gold standard top-dollar S54 swap is an expensive engine for something that went out of production over 10 years ago.

I think the reality is that all of the above engines with the S54 tacked on are probably exactly the same difficulty to swap. The M54 is probably the most cost effective, lightest, and best availability for lower mileage donors... but don't forget even that engine went out of production 13 years ago, so low mileage examples in salvage condition are few and far between.
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Old 02-19-2019, 12:19 PM   #3
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N52/N54 should be considered as well. Basically most 24v swaps require some sort of oil pan or subframe shenanigans.

But I think more and more, people are going to be more interested in building original E30 engines than doing swaps. A 30 year old worn out M50B25 isn't really an upgrade anymore (not that it was much of one to begin with).
Build thread

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Old 02-19-2019, 02:15 PM   #4
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All very interesting perspectives.

Its interesting you mention building the m20 Nando (and I saw from your ix thread that you have done just that). My previous daily driver was an air cooled 911 and maybe on account of values maybe on account of lack of truly modern swaps, there was deep knowledge about NA builds. I am naturally of the originality and simplicity school. An unusual number of threads concerning M20 improvements or repair end in ‘swap’ or ‘boost’. Upfixing the motor that came with the car is not lost on me, but neither is the prospect of a light weight fuel efficient more powerful replacement.

Noted on age of 24v donors, but also noted that the rather low cost of all of the above except maybe S54 means (I at least) would be doing a fairly comprehensive maintenance program while the motor is on the bench.
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Old 02-19-2019, 03:49 PM   #5
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Even just putting modern aftermarket engine management onto an old engine transforms a 30 yr engine into something much more modern feeling. My M20 with proper acceleration enrichment, dizzy-less ignition and map sensor over AFM makes the engine feel very modern. Granted one does need to spend alot of time learning to tune it properly. Cant just bolt it in.

Fuel efficney has greatly increased with my tune too. 9L/100km not bad for a 30yr old 6clr.
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Old 02-19-2019, 04:01 PM   #6
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I went through exactly this thought process over the last two years while I plugged along with my m20b27. I thought "these 24v conversions seem like a lot of trouble... and the stroker builds with the eta short block and 885 head seems like a lot of guesswork... SOMEone must just build reliable breathed-on m20's."

Yea. Someone Does:


That's a lot to pay for 200hp.

All of this resulted in my buying a scrap shell to play around with the idea of the 24v swap so that I can keep my m20 on the road in the meantime and scrap the whole thing if I decide to.
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Old 03-11-2019, 08:33 AM   #7
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After a lot of research I chose the m54, if you're interested you can check out my thread.

Donor Motor - year, model, cost:
E39 530i 2001, 180k km, 1900 euro

ECU / Harness - year, model or standalone

ECU Elements Deleted / Flashed :
DIY EWS delete flash, still have to remove rear cats

Harness Adapter - DIY, purchased, from who:
DIY Wired in the original loom

Headers - and comment on fit
m52 528i headers

Brake Booster - year, model
Reanult Clio 2001
M54B30 E30 build:
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Old 03-21-2019, 04:33 PM   #8
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I think the M54 is the best of the proven swaps right now as long as your goal isn’t maximum power. I’ve driven one, and you won’t regret it.

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Old 03-21-2019, 04:47 PM   #9
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I recently pulled my first 24v, a m54B30 out of a 530i. The local pick your part had a 40% of sale and the full long block was 240$.

Jordan has a really good thread on his one build as well as a guide.

The 530i Is the best car from my research to pull a motor from. They are easy to find, big engine bay, and usually less beat on.

Definitely spend the time looking for a 3.0L over a 2.5L, there common and at a junkyard you won't pay more. Also grab the ecu, harness, and gas pedal from the 530i.

Don't bother with a zhp 330i motor, they make at best 5 hp more, from my research.

There's swap harness for the m54 pre made available in R3V. 450$ and tunes as well to make the ECU operate in another chassis.
91' 318is 90' 325is

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Buy the E30s, they ain't gonna last long
E30 can make you, E30 can break you
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