M90 Engine - Serial/production numbers, Specs, Pictures

[Lieuwegaal]

Hi all,

I have been googleing a lot found a lot of info on the M90 engine so far. Still all this info is shattered all over the WWW.
Now I am getting everything together for my M90 build and I'm sure there are more people out there working or will be working on a M90 in the future (COVID-19 stay of the street and stay safe in the garage style), that are curious about the info there is.

First I must say the info I found was great and many of you helped out already. I've posted the links of those threads at the bottom of this post.

My goal is to get as much info into this first post if possible (If need with you're credits mentioned behind it).

For this topic I will be going over the Engine block, crankshaft and piston assembly. Mainly because the cylinder head is a lot of more and maybe we can add that later.

Please feel free to help or submit comments on the into that's here.

As I am having a engine that's been worked on by I believe many people. I might be wrong with some numbers/specs.
Please correct me if I am wrong.

Let's all work together to make this engine info less rare to find

+ I'm looking into getting new pistons and I've seen a lot of posts about this, please let me know if you have suggestions ( I am based in The Netherlands)
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Engine Assembly - BMW S30B35LE



VIN location: above starter (mine: x5747345x)

The 3453ccm unit for the E24 was manufactured until 03/1982
The 3430ccm unit for the E24 was manufactured from 12/1981

=============== Specs: ===============

Compression: 9.3:1
Power: 218bhp/5200rpm
Torqure: 224lb.ft/4000rpm

--------------------------------------------------------------------------------------------------------

Engine blok M90.
Realoem

01 - Engine block with piston [1] - 11111270804 (09/1982)
01 - Exch. engine block with pistons[1] - 11111289578
01 - Exch. engine block with pistons[1] - 11111289578

For vehicles with Low compression engine S858A=Yes:
01 - Exch. engine block with pistons [1] - 11111286540 (09/1983)
https://www.realoem.com/bmw/enUS/showpa ... Id=11_0104

=============== Numbers: ===============
- Exhaust side:

• 127006 - ?
  

• 15L79 - production date (would be nice to add a list of Letter to month)
  

Letter I was not used so August is H, September is J and December is M.
Example: 23L79 is 23 November 1979 and 8B80 is 8 February 1980

• 1Z - ?
  

- Intake side:

• 3.5 - displacement
  

• 1Z - ?
  

• EB - ?
  [/url]

=============== Specs: ===============

• Material - ?
  Bore - 93.4x84 [mm]
  Displacement - 3453 [cc]

=============== Additional info: ===============
2 passages between cylinders


--------------------------------------------------------------------------------------------------------

Crankshaft:

01 - AT-crankshaft with bearing shells [1] - 11211304928 (09/1982)
01 - AT-crankshaft with bearing shells [1] - 11211278799 (HUB 86 MM)
01 - AT-crankshaft with bearing shells [1] - 11211278799 (HUB 86 MM)
01 - Crankshaft without bearing shells [1] - 11211705770 (HUB 86 MM)
01 - Crankshaft without bearing shells [1] - 11211705770 (HUB 86 MM)
01 - Crankshaft with bearing shells [1] - 11211278800
01 - Crankshaft with bearing shells [1]- 11211278800
https://www.realoem.com/bmw/enUS/showpa ... Id=11_3044

=============== Numbers: ===============

• 1304921 - ?
  ᛟ2G - ?
  
  
  CK45BMW - ?
  

=============== Specs: ===============
Material - ?
M30 stroke = 86 mm
M90 stroke = 84 mm

=============== Additional info: ===============
NA

--------------------------------------------------------------------------------------------------------

Pistons

01 - Mahle piston - 93,36MM("0") - 11251278110 (09/1982)
01 - Mahle piston - 93,44MM("00") - 11251278111 (09/1982)
01 - Mahle piston - 93,56MM(+0,20) - 11251278112 (09/1982)
01 - Mahle piston - 93,76MM(+0,40) - 11251278113 (09/1982)
01 - Mahle piston - 91,97MM("0") - 11251286435
01 - Mahle piston - 91,97MM("0") - 11251286435
01 - Mahle piston - 92,05MM("00") - 11251286436
01 - Mahle piston - 92,05MM("00") - 11251286436
01 - Mahle piston - 92,22MM(+0,25) - 11251286437
01 - Mahle piston - 92,22MM(+0,25) - 11251286437
01 - Mahle piston - 92,47MM(+0,50) - 11251286438
01 - Mahle piston - 92,47MM(+0,50) - 11251286438
For vehicles with Low compression engine S858A=Yes :
01 - Mahle piston - 91,97MM("0") - 11251286435
01 - Mahle piston - 92,05MM("00") - 11251286436
01 - Mahle piston - 92,22MM(+0,25) - 11251286437
01 - Mahle piston - 92,47MM(+0,50) - 11251286438
=============== Numbers: ===============

• Sp0.05 93,55 (on head of piston) - Piston Skirt Clearance + Cylinder Bore [mm] (Ø)
  Mahle - supplier
  
  
  +++93V54 - Casting Number
  
  
  R011 - ?
  6 79 - Production (?)
  

=============== Specs: ===============
Cylinder Bore [mm] (Ø)- 93.4 mm
Top land height [mm] (F) - 8.0 mm
Length [mm] (L) - 73.0 mm
Distance between bosses (AA) = 26.5 mm
Compression height (KH) - 41.0 mm
Pin I.D. - 13.0 mm
Pin O.D. (BoØ) - 22.0 mm
Surface - Sn
Pin Length (BoL) - 71.0 mm
Casting Number - 93V54
Material - M124
Casting Type - V
Compression Ratio - 9.3
Piston Skirt Clearance - 0.05 mm

Ring 1(RC1) - 1.75 Rectangular ring
Ring 2(RC2) - 2.5 Taper-faced-ring
Ring 3(RC3) - 4.0 Coil spring loaded bevelled edge oil control ring

=============== Additional info: ===============
https://catalog.mahle-aftermarket.com/e ... 75#divider
https://catalog.mahle-aftermarket.com/e ... 90#divider

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Connecting Rod

01 - Connecting rod - 11240618006 (L=135MM)
02 - Connecting rod bolt - 11241719991
03 - Connecting rod bush - 11240618100
04 - Bearing shell - 11241258428 (48,00MM) 01/1984
04 - Bearing shell - 11241258429 (47,975MM) 01/1984
04 - Bearing shell - 11241258430 (47,750MM(+0,25)) 01/1984
04 - Bearing shell - 11241258431 (47,500MM(+0,50)) 01/1984
04 - Bearing shell - 11241258432 (47,250MM(+0,75)) 01/1984
05 - Hex nut - 11240518321 (M10X1)
=============== Numbers: ===============
I could not find any numbers?

=============== Specs: ===============
I did not find any specs/manf or so ?

=============== Additional info: ===============
Lubrication hole at piston connection needs to face forwards when installing?


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https://bigcoupe.com/phpBB2/viewtopic.php?t=27510
https://bigcoupe.com/phpBB2/viewtopic.php?t=4181
https://bigcoupe.com/phpBB2/viewtopic.php?f=2&t=1296
https://bigcoupe.com/phpBB2/viewtopic.php?f=7&t=30466
https://bigcoupe.com/phpBB3/viewtopic.php?t=9827
https://bigcoupe.com/phpBB2/viewtopic.php?t=30275

https://e9coupe.com/forum/threads/m90.18410/
https://e9coupe.com/forum/threads/is-this-an-m90.23368/
https://e9coupe.com/forum/threads/3-5l- ... lock.9768/
https://e9coupe.com/forum/threads/m90-pistons.11500/

https://www.mye28.com/viewtopic.php?t=11076
https://www.mye28.com/viewtopic.php?f=2&t=143512
https://www.mye28.com/viewtopic.php?t=53595

https://www.e30zone.net/forum/viewtopic.php?t=259390
https://www.bimmerforums.com/forum/show ... M30-vs-M90

https://firstfives.org/phpBB-3.2.1/phpB ... f=4&t=5867

[bpoliakoff]

So having had my M90 rebuilt, nothing really mattered as I had the engine bored to where the cylinders cleaned and had pistons made to match with a true 10:1 compression. Where it got tricky, was how much the head was milled and the block decked. The block deck will determine wrist pin location as to designing the dome for valve clearenc. CC'ing the combustion chambers will determine dome height on the pistons for compression ratio. If you are rebuilding and just cleaning the bores you will have to go to next standard oversize piston and nothing else matters. If you use the standard M30 crank with a longer stroke you will increase engine size and this is not an uncommon swap but now the pistons have to be made so everything is in accordance. If you stay with stock valves probably the wear will be in the valve guides and seals. I think you may be over engineering this `with all the info you have gathered and if you are doing a complete rebuild let the machine shop figure out the measurements as that is what you are paying for. My pistons with wrist pins and rings, made to spec, were about $1000 and quoted by three highly rated piston manufacturers within a few dollars of each other. The head work, with existing valves, porting and cc'ing the combustion chambers ran $750 and a 284 regrind of my existing cam with over sized eccentrics ran $10. My car is a first year Motronic and last year M90. I am guessing yours is Ljet and don't think it can handle those mods without you going to a later injection system

[Lieuwegaal]

Thanks for sharing your experience with the engine. This was really useful for me and hopefully others.

My goal is not to engineer everything out but as there is info everywhere and people are looking for info,
I thought this might be a nice spot to gather all of it.
I'm still going thru the topics/comments and add to the first post.

I'm still looking for the right machine shop here in the Netherlands that not just treats this as a M30.
I'm going for a stand alone ECU as that fits my project goals.

We just need to show these first 3.5L BMW engines the love and respect

[bpoliakoff]

I personally would not use a B34/B35 crank as the the M90 has torque that pulls like a freight train due to the shorter stroke. I would concentrate on compression, head work and a reasonable cam which should put you around 260hp and I don't know how much more the stand alone will give but definitely add to it. Maintain the 2" exhaust system. If you go headers, the ideal size primary tubes should be 1 5/8 If you go 2" you will lose bottom end torque

Not cheap, but Stahl long tube headers are the gold standard at about $1100. If I go headers I will go that way. I have done a bit of research on various forums and have found that to be a general concensus from a fair amount of guys who have built modified M30 motors and know what they are talking about over the years

[Lieuwegaal]

Hi bpoliakoff,

Don't get me wrong I would love to put in a M90 crank but this it the crank it came with..
This morning I measure the stroke of the crank and it's 84mm as I assumed by the numbers on the crank.
Keeping my eyes out for a M90 one but I believe these are hard to find.

Great advice on the head and headers . I've just looked into the Stahl headers, still need to do a bit more research but I put that one my list

The Stand Alone ECU was more about if I would go for the Turbo but I'm not sure of the larger bore of the M90.
First have to figure out to keep this crank and what pistons to add with them + checkout the head that came of this engine.

Again I believe a lot of people worked on this car/engine so that's why I am checking everything and hope to help someone else out with info as well.
Good thing is it ran couple of months ago

PS. checked your pictures on flickr. Look good and motivates me on my project.

[bpoliakoff]

It's a shame you are so far away as I have an M90 crank that needs to be ground. It came out of my car as I was lucky enough to find one that was standard in mint condition

[Pasocb]

"=============== Specs: ===============
Material - ?
M90 stroke = 86 mm
M30 stroke = 84 mm"

Don't get me wrong I would love to put in a M90 crank but this it the crank it came with..
This morning I measure the stroke of the crank and it's 84mm as I assumed by the numbers on the crank.
Keeping my eyes out for a M90 one but I believe these are hard to find.

Hi Lieuwegaal,

Perhaps you have your crankshaft dimensions confused:
-Most M30 engines have an 86mm stroke
-The M90 engines have an 84mm stroke

One of the unique features of the M90 engine is this short stroke shared by the M-tech engines.

[Lieuwegaal]

"=============== Specs: ===============
Material - ?
M90 stroke = 86 mm
M30 stroke = 84 mm"

Don't get me wrong I would love to put in a M90 crank but this it the crank it came with..
This morning I measure the stroke of the crank and it's 84mm as I assumed by the numbers on the crank.
Keeping my eyes out for a M90 one but I believe these are hard to find.

Hi Lieuwegaal,

Perhaps you have your crankshaft dimensions confused:
-Most M30 engines have an 86mm stroke
-The M90 engines have an 84mm stroke

One of the unique features of the M90 engine is this short stroke shared by the M-tech engines.

Damn that was a typical Friday.. You are right. I've mixed it up
I will update the first post and turns out I do have the M90 crank then.