S52 Head on a Z3 M52TU block?

[Chilezen]

I bought somebody's blown S52 (not knowing it was blown) so I'm playing around with ideas on what to do with this.

Having dissembled nearly the whole motor, I found a spun rod bearing, and metal debris had been carried through the oil and scored most moving surfaces; the crank, piston skirts and cylinder walls, the cams and cam trays, and I think the lifters. I'm getting the impression that this whole thing is toast, and it would be cheaper to buy an engine in better condition, rather than repair anything here.
But out of cynicism and stubbornness, I went to the junkyard to pull a crank and rods from an M54B30. This made me feel better about no longer needing to repair the damaged crank I had.

But after hearing a mechanic's opinion about the pistons I intend to reuse, his fingernail-test suggests the pistons need replacement and the cylinder walls need more than a simple honing. Essentially, the block (and almost everything else) I have is toast.


~~~~~


I've heard people complain about the extra weight of 24v motors upsetting the balance in the E30, however the aluminum block from Z3 alleviates this issue.

So if I want to build the ideal motor, I should:

• Find a 1999-2000 Z3 M52TU block, because of the stronger cylinder walls (earlier blocks reported premature cylinder wear from high-sulfer gasoline(source 1)(source 2))
• Use my M54 crank, because I hear it's a common swap to increase displacement and torque in regular M52's
• Use M54 rods and pistons, thus producing a 3.0L engine with 10.3:1 compression ratio
• Use the S52 head I have, for its stronger springs and single VANOS (versus the dual VANOS of the M52TU, because that's more wiring that I don't want to deal with in the S52 harness I have)
• Buy good-condition S52 cams and trays and lifters

To your knowledge, would these parts work well together?

I think that takes care of all the major mechanical bits, aside from the regular 24v parts list. I'm not sure which ECU to use; suggestions?

I'm using this guy as a build reference, he declares parts of this should work, but he doesn't mention the dual-to-single VANOS conversion, or the aluminum block as a part of the equation.

[wworm]

Bummer about buying a blown motor, that sucks man

iirc, you've got a few things incorrect here.
1- The m52tu coolant ports wont line up with an s52, dual vanos engines are incompatible with single vanos engines (I'm only referring to my knowledge on m54/m52 compatibility, idk much about the m52tu)
2- the harmonics of the m54 rotating bits are known to strip threads in the aluminum block m52's

You're best off getting a non TU block and putting the s52 head on that, while keeping it a 2.8. 2man's "aluminum monster" and dmitriy's white car's threads both go into the details a bit more.

You'll want to use an ms41.1 ECU, as it keeps things obd2 for BAR

[TheRob]

A good friend of mine up in the Bay Area built an m50 with the m54 rotating assembly and it made great power but, as wworm stated, something about the harmonics from the m54 parts, in his case it was causing his clutches to blow apart. He'd run drift events on a regular basis so the extended RPM and high load probably amplified the issue.

Also, I found this the today during my regular craigslist browsing, he fails to mention if it's a 2.8 though but if it is this would be ideal for the swap you're talking about.

https://orangecounty.craigslist.org/cto/d/westminster-bmw/6869896415.html

There was a member on here who converted a dual Vanos m52 to a single Vanos "m50"

https://www.r3vlimited.com/board/showthread.php?t=374572

[Caperix]

What about using the ati dampener on the engine? I have heard good things about it but no first hand experience

[Chilezen]

1- The m52tu coolant ports wont line up with an s52, dual vanos engines are incompatible with single vanos engines (I'm only referring to my knowledge on m54/m52 compatibility, idk much about the m52tu)
2- the harmonics of the m54 rotating bits are known to strip threads in the aluminum block m52's

You'll want to use an ms41.1 ECU, as it keeps things obd2 for BAR

1- At this point I'll take your word for it, but I can't see why the dual-vanos M52 head would have the passages relocated versus a single-vanos M52 head; that would mean iron block M52TU's are different than normal M52 blocks.
Without question, the M54 head wouldn't fit.
2- That's interesting. Do you have a source on this? What threads are stripped?
3- Which car is the ms41.1 in?

And the purpose of the TU block was for the updated cylinder walls, as I cited originally. Otherwise this thread wouldn't be necessary, because I know those parts would fit. Thank you though.

A good friend of mine up in the Bay Area built an m50 with the m54 rotating assembly and it made great power but, as wworm stated, something about the harmonics from the m54 parts, in his case it was causing his clutches to blow apart. He'd run drift events on a regular basis so the extended RPM and high load probably amplified the issue.

Also, I found this the today during my regular craigslist browsing, he fails to mention if it's a 2.8 though but if it is this would be ideal for the swap you're talking about.

There was a member on here who converted a dual Vanos m52 to a single Vanos "m50

I've thought about getting a new harmonic balancer from ATI. Pricey, but I know stock units can go bad because they aren't tuned for higher RPM's. Now I'm no drifter, but I'm not surprised that a drift car blows clutches

I contacted that Craigslist ad both through email and text, back on Thursday! Haven't heard back. Seems too good to be true.

I've seen that thread, but he's using a full M54 engine and retrofitting it. It's not quite what I'm trying to do. Plus, I don't like that idea because the head ports aren't the same, you'd have turbulent airflow unless the ports are machined to match.

What about using the ati dampener on the engine? I have heard good things about it but no first hand experience

Yeah totally, it's a worthwhile investment.

[Caperix]

The m52tu has reverse flow cooling like the m54. The block has an extra coolant passage to the head preventing the heads from being swapped. I have heard of people running the dual vanos engine off single vanos ecu's. Probably better to use a can contoller and mount a drive by wire gas pedal & just run a m54.

[wworm]

ms41.1 is any m52 (single vanos) engine

[Chilezen]

The m52tu has reverse flow cooling like the m54. The block has an extra coolant passage to the head preventing the heads from being swapped.

No way! Shoot. Thank you!

I can't plug the extra passage in the TU block to make it compatible with an earlier head?

[pazi88]

No way! Shoot. Thank you!

I can't plug the extra passage in the TU block to make it compatible with an earlier head?

No. The cooling system is totally different.

[Chilezen]

So I was digging around and found 2mAn's engine build thread (as recommended), and it was a great read! There's a couple things in there that stand out to me:

Oh, and BTW, the alu block is not crappy at all. You just need to run the proper thermostat. When BMW started using alu blocks, they also chose to raise the operating temperature of the engines, to improve emissions. This makes the engines more prone to overheating and warping. And even then, its the head and not the block that gets most of the damage. Aluminium has a better thermal conductivity, so it stays cooler easier than iron blocks. It just need the coolant at a proper temp. Change that thermostat from the original 105c, to 85c, and you wont have temp issues again.

The only real weak point in the alu blocks, its the threads for the head bolts. Studs there is a must.

Even the issue with the nikasil liners can be solved by using steel liners like the later M52TU or M54 (allthough in this case since its from a Z3, it should have the alusil liners so that should be fine).

This is generally good news & good advice. He mentions the cylinder sleeves that I was concerned about, and suggests using head studs. I favored head studs for my build. Somebody elsewhere had said, "Head bolts are an accountant's decision. Head studs are an engineer's decision." and explained the difference in forces of those two fasteners, how studs are better than bolts.

FYI, the M54B30 failure mode is actually shearing off the oil pump gear. Not unwinding the nut.

Anyone else hear this? It's the first I've seen.

Then a new conversation begins about head studs:

I was hoping you might remember some of the details on the timesert-ing process;

I've been considering this process for my N/A aluminium M52B30 build, but I've been seeing a fair bit of conflicting info in terms of timesert type to use, and the compatibility with ARP studs - what combo did you use?

ARP's own website only shows cylinder head kits for the iron blocks, nothing for the Euro M52 (alu).
And my understanding was that those ARP studs are too long for the threads created by the timeserts, when installed in the alu blocks

Why do you need ARP's for NA engine. Or even the timeserts if the threads are fine? The stock bolts are fine even in mild boosted engines.

I don't know the history/ mileage of the block, and from what I've read, stripping threads is possible if the alloy has softened due to excess heat cycles. Seems like a worthwhile 'while I'm in there' job...
Plus supposed possibility of using ARP bolts, which can be re-used

I'd skip the ARP stuff personally unless you're building some turbo monster you should just use an iron block.

Time-serts, on the other hand, serve a real purpose on the aluminum block motor. My mechanic told me it was a factory recommended repair when removing the head on a high mileage motor. The concern was behind torquing down a head on an aluminum block that it might pull the threads rather than stretch the bolts.

Your results may vary, but I had a motor with an unknown history so I chose the insurance policy of doing them.

I agree. Don't use ARP or any other non-stretching bolts with alu-block. if you have to, use them on an iron block.

But I have experience on several alu-blocks and if the threads look fine, there is no need for timeserting. But for example if you see aluminium in the head bolt threads when you remove them or strange corrosion in the threads in block, then you need to timesert them.

But If you need to timesert the threads I have video showing how you can do it without buying that ridiculously priced thread repair set for m52 engine:
https://www.youtube.com/watch?v=lXGm5_Vogy4

Don't do ARPs. I would timecert though. If the motor has ever gotten hot at all the threads will pull on the 3rd torque stage and then you have to pull the head back off and timecert anyway.

One certainly *CAN* use ARP's in an aluminum engine... they just need to be used with the right torque sequence.

I am getting mixed results here.

[pazi88]

Well many people don't recommend to use arp bolts in alu block ;) And also you can make +500hp with just stock headbolts and proper headgasket.

[Chilezen]

I don't have a problem using oem bolts, but is there another company that produces more suitable studs?
And what about main caps? Studs could be used there just as well.

[pazi88]

Just use oem (or some febi etc. oem equivalent) and oem torq specs and everything will be fine and go easily. Why make things complicated?

[Chilezen]

Alright alright. No need to be fancy.

Anyway I started this thread because I saw a '99 Z3 for sale for $400. The ad was dismal, lacking details. I wondered if my parts were compatible.

Tonight I bought that Z3. It's actually a '98, pretty sure single VANOS, 2.8L, which means all the parts from my blown S52 could fit! I'll confirm tomorrow morning when I dig into it.

For the price, though, I can make the money back easily by selling Z3 parts. Excellent

Edit: The sunnofabitch is an iron block! God dammit

[wworm]

Edit: The sunnofabitch is an iron block! God dammit

what?! that shouldnt be the case...must have been swapped at some point. Whats the serial #?