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Old 04-21-2019, 01:30 AM   #1
Chilezen
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Deciding what to do with a blown S52, to possibly pursue a CA-legal S50

My E30 has been feeling sluggish for almost a year now, so I've been looking at options.

First idea was to replace the head gasket on my oil-leaking M20; I found a drip on the exhaust side between the headers, and I'm adding a quart of oil maybe once a month. So I bought an M20 head, a complete gasket kit, timing belt, water pump, head bolts... the whole top-end kit. I disassembled the head, ready for a light machining and testing by my local engine machine shop.

But that head has been sitting in my garage and my car still leaks. Instead, I've nearly abandoned that idea because I did a compression test, and my #4 cylinder is pretty low. I poured in a little oil and the reading spiked up to normal (bad rings confirmed). So refreshing the top end won't really solve my sluggish engine; the whole motor could use a refresh.

With that in mind, I looking into 24v swaps. I've been sitting on the idea for months, waiting for something magical to happen.


As such, when a friend mentioned he had an S52 for sale, my attention was drawn. Described as "needing a bottom end rebuild," for $600 which included the motor & auto trans & ebay headers and complete harness, I thought

"Yeah, I can tackle this. How bad could it be?"

I bought the motor. It was night when I first saw it/picked it up. Just as a precaution to make sure oil didn't spill everywhere, I undid the oil pan bolt to drain whatever might be there. Only a few drops of water came out. I thought "okay cool, the oil's already been drained." We loaded the engine in my car and I took it home. (Yes, an S52 does fit in the passenger compartment with the seat taken out, if you were wondering.)

Upon disassembly, the reason only drops of water came out was because the milkshake mixture was clogging the rest of the oil from draining. The cam journals were scored from metal debris. Where from, you ask? This motor spun a rod bearing. And all that bearing material cycled through the motor, tearing up all the critical surfaces. Unrelated, but some of the exhaust threads in the head for those studs are jacked up, from when the previous owner ripped them out and reinstalled them for his shitty headers.

My "friend" (the seller) isn't about to give me my money back. So I basically have a heavy paperweight. I was able to sell the e36 oil pan though, so that was nice.


Given the circumstance, I researched and learned an M54 crank and rods will perfectly replace my torn-up crank and rods. So went to the junkyard with a buddy, and spend 5 hours tearing apart a 330. For less than a hundred bucks, I have a "new" crank and rods.

This news is fine and all, but I still need to replace the cams. I know I need to replace the cam trays too. I'm not sure if I should get a new head, due to a few of those ugly exhaust threads. Maybe it's not a big deal.

Naturally, I will check the head and block for cracks, so at this point I can't even assume the worst of my troubles are over. Right now, all I really have worth value are the M54 parts.


I've been sitting and reading for hours and hours, and I've learned this crank can be used in any of the M50/S50 engine to increase throw/displacement. What I haven't fully understood is the effect this has on compression ratios and the differences in piston/wrist pin height.

On top of all this, I do have the goal of BAR'ing this car, because being legal in CA has the benefit of not being fined/impounded. But I don't have any paperwork regarding the S52, nor am I certain I have all the other necessary emissions equipment. I don't believe this motor came with the EGR pipes coming off the headers...which weren't factory anyway.

Since it feels like I'm sitting on a goose egg, I'm seriously bummed, and disgraced with myself for what was essentially an impulse buy disguised as a good deal.


Questions I'd like answers/suggestions for:

1) Given the scenario, what might you do? Start over? Scrap what I have? Sell what I have to save up and buy a complete setup to BAR it? Or keep what I have to assemble a complete S52?

2) I'm also stuck in thoughts, wondering if I can find a clean/documented M/S50, and then drop in the M54 crank to gain that extra torque, and still pass it legally under the CA ref? As long as the emissions equipment and tailpipe readings are legal, what does it matter if the crank is different?

3) In the meantime, should I return my attention to the M20 head, clean it up, reassemble it, and pop it on my car while the S52 stares at me every time I am in the garage? A part of me still sees no point in installing a clean head on a tired block.

I am so tired of reading incomplete threads across multiple forums. I've spent weeks reading & researching and this is what I've amassed. Please suggest relevant ideas...
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Old 04-21-2019, 03:51 AM   #2
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Keep the m5x crank, buy a crank spacer, drop some coin on a set of pistons and rebuild that m20. Basically a stroked m20. No crazy exhaust at this time, no BAR, just a squiddd chip.... hopefully your cat is good enough to pass the sniffer.
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Old 04-21-2019, 11:23 AM   #3
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I know the engine you speak of and I'm sorry it didn't work out. You'd think that those in the community would look out for "friends" but that isn't always the case. It was very tempting but i'm wary of those kind of engines "only needing a rebuild." The good thing is you can get an M50 engine cheap and nearly all the parts transfer over. It all comes down to your goals and how much money you can dump into it. PYP has also had a couple of E36 M3's drop in OC. If you signed up for notifications and you're fast with a little luck you could score an S50/S52 if you keep an eye out.

Now, i'm an old timer who has always preached stroking the M20 vs 24v M50 swap but these days it makes more sense to go 24v as the swap is well documented and one can find all the parts they need at the junkyard. Stroking the M20 back in the day was born from necessity. The ultimate NA M20 build would have had RD's 24v head (ultra rare = $$$) and been stroked to 2.8/2.9/3.0 liters and cost about 10k back in the day. But think about it...that's what an M52/S50/S52 is. Even an M50 with cams can make good reliable power in the E30 while the M20 will always be hindered by the 2 valve head, timing belt and AFM. If originality isn't an issue...24v swap it.
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Old 04-21-2019, 06:24 PM   #4
Chilezen
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Quote:
Originally Posted by uturn View Post
...and rebuild that m20.
I'd prefer to use the full M5x platform for its newer electronics and engine management, versus the M20.

Quote:
Originally Posted by reelizmpro View Post
I know the engine you speak of and I'm sorry it didn't work out. You'd think that those in the community would look out for "friends" but that isn't always the case. It was very tempting but i'm wary of those kind of engines "only needing a rebuild." The good thing is you can get an M50 engine cheap and nearly all the parts transfer over. It all comes down to your goals and how much money you can dump into it. PYP has also had a couple of E36 M3's drop in OC. If you signed up for notifications and you're fast with a little luck you could score an S50/S52 if you keep an eye out.
Yeah this shit still happens. The seller was lucky to pass it on to someone else.

I think I will find a complete M50 with everything instead of waiting for an S motor to pop up. This sounds like the best option. Cheaper to obtain those parts to meet regulations, but can make the bump in power. Although I would still need to find S50 cams.

Quote:
Originally Posted by reelizmpro View Post
Now, i'm an old timer who has always preached stroking the M20 vs 24v M50 swap but these days it makes more sense to go 24v as the swap is well documented and one can find all the parts they need at the junkyard.....the M20 will always be hindered by the 2 valve head, timing belt and AFM. If originality isn't an issue...24v swap it.
Yeah I'm set on 24v now. I realize the importance of airflow with 4 valves. And better electronics, etc.

I'll be visiting the Midtown meet again to ask questions about BAR'ing an "M50" engine legally.



I wonder if I can easily convert an M50 to OBDII? I haven't yet figured out how the harnesses and blocks are different; as far as I know, there's a crank speed sensor in the back-side, and better knock sensors. I would use my S52 block if I could but I hear that the techs know the difference between OBDI & II blocks... so I'd have to use the M50 block to pass the visual, right?
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Old 04-22-2019, 12:38 AM   #5
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If you're dead set on a 24v swap, see if you can find a running donor vehicle. When I did my swap, I was able to purchase my motor from a running e36, which allowed me to do a compression check on the motor and hear it run before the motor was pulled.

I'm not sure how the BAR process is these days for OBD1, but the last two cars I did (2015 and 2016), the rules were that everything had to be stock from the MAF to the cats. During the inspection, the ECU needed to be hanging in the glovebox so the ref could run the VIN number and verify the donor motor. Exhaust is where things get tricky, as some refs will be ok with an exhaust that matches the donor car configuration (aka custom exhaust with correct routing and CA legal e36 cats), while others will only allow an unmodified stock e36 midsection. Once the car is done being inspected, THEN they will do the roller smog test. Might be worth a phone call to get more specifics on the process to see if anything has changed.

If I were to do things again, I'd probably just build a fresh stroker m20 and call it a day. Even a basic 24v swap is 5k by the time you refresh it, and you're still left with a used motor that most likely has 100k+ miles. Factor in the time to get an appointment and go through the BAR process (assuming you pass the first time, usually not the norm), and a rebuilt m20 seems more and more appealing in California.
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Old 04-23-2019, 08:45 AM   #6
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I've been working on a BAR legal M50 swap for a little while now. It's been a longer process because I bought someones failed project. So I basically started with just and M50 with no emissions stuff. The only reason its not CARB legal right now is because it failed the sniffer but I think I've got that nailed down. Sometimes I wish it was still and M20 so I didn't have to got through all this. Personally, I would slap that good head on the M20 and drive it while you rebuild the S52. I've gone on a little bit below about various things regarding the Carb legal stuff. Also, none of the M/S engines have a EGR but the OBD2 engine will have air injection which you will have to have functioning for the test.

The only thing the REF said that has changed, is the BAR now requires proof of your engines original emissions certification. So you have to have proof it's a California Emissions engine and you can not put a federal engine into a California car. I got lucky and the ref was able to look up the past smog tests via the vin on the back of the head and since the car was smogged as a California emissions car it was good. So whatever car you decide to get an engine from, grab the under-hood emissions label while you're there or if you use the S52 just write down the VIN that tagged on the back of the head.

The upside to going the m50/52 is that the Pick ur Parts around the LA/OC area are littered with 325/525/328 BMWs and if you need spare parts they can be had for cheap. I got most of my emissions stuff like my charcoal canister, purge valve and mid pipe minus a cat from the yard. As far as E30s go finding them in a yard or good deals on used parts locally is getting harder to do.

The exhaust is fairly simple for someone who can weld and has some experience with exhaust work, my exhaust is almost all e36. The midpipe is from a junkyard and my cat is a CARB approved Magnaflow, if you can get them at cost this is the most cost effective way to do it. No tech will have a problem with it and because my mid pipe is unmodified, the cat is in the correct location and the 02 sensor is also in the factory spot.

A small upside to the M50 is because its OBD1 the emissions stuff is a bit more simple. There are no monitors to run, the evap system is just a charcoal canister and a purge valve, only has one 02 sensor and you don't need a CARB approved air intake as anything before the MAF does not require a sticker.

If you are going to do an OBD2 engine just start with an OBD2 engine and run it as it came from the car, you can slap the M50 manifold on after you've gone through the REF and are smogging the car with normal smog techs who probably don't care or know the manifold is different. The OBD2 will offer better tuning capabilities and easier diagnostics but its a little more involved with the swap and I would recommend getting a donor car for either option if you decide not to use the S52.
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