M90 cylinder head ??

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paul burke
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M90 cylinder head ??

Post by paul burke »

Does anyone have one of these heads or pictures of the intake side (less manifold)?


Paul

Mike W.
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Post by Mike W. »

Paul, you have hit on the 64K question that few even think to ask. For years I've been trying to figure out what is so special about M90's, if it's just rumor or reputation or if there is really something special. An extra 23CC's. Big deal. 9.3 vs 10:1 compression on later euro 3.5s should mean less, not more. I've heard of some detail differences in the block that make them more like early 2.8s or whatever, but nothing to make more HP. Heads, by PN, seem to be the same. Never having driven one I'm thinking it was just head and shoulders above the rest of the pack then and was improved upon later in the M30 run. But I haven't driven one. And why are they the same HP as later 10:1 3.5s? All of which says to me if there is a difference it's in the head. :D

If they heads are the same as regular M30s, I probably have one. If they're different, no.

derrith
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Post by derrith »

I have two heads with the casting mark of m90. One is from an early 533, the other from my early euro 10:1 735i.

If you cross the head casting part number in realoem the m90 head was used in those two applications.

ElGuappo
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Post by ElGuappo »

I wanted to take some side by side by side pics with M90 B34 and B35 side by side. Intake, exhaust and combustion chambers.

Mike W.
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Post by Mike W. »

derrith wrote:I have two heads with the casting mark of m90. One is from an early 533, the other from my early euro 10:1 735i.

If you cross the head casting part number in realoem the m90 head was used in those two applications.
Where are you seeing the M90 designation? All the heads I've seen from Bavs up into the early 80's have the same casting number, 1 250 019, slightly later ones were 1 304 473, early US B34s seemed to be 1 277 358, later US B34s were 1 288 086, but Realoem doesn't recognize any of the numbers. The early number is especially interesting as there were at least 3 distinctly different castings with that same number.

derrith
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Post by derrith »

Mike W. wrote:
derrith wrote:I have two heads with the casting mark of m90. One is from an early 533, the other from my early euro 10:1 735i.

If you cross the head casting part number in realoem the m90 head was used in those two applications.
Where are you seeing the M90 designation? All the heads I've seen from Bavs up into the early 80's have the same casting number, 1 250 019, slightly later ones were 1 304 473, early US B34s seemed to be 1 277 358, later US B34s were 1 288 086, but Realoem doesn't recognize any of the numbers. The early number is especially interesting as there were at least 3 distinctly different castings with that same number.
The head I was looking at cross references here. M90 mark seen here:
Image

Mike W.
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Post by Mike W. »

Interesting, I've not seen that before, either from not noticing or it not being there. But I'll have to take a look at some of my collection, at least one head I replaced one time would have fallen in that range but I didn't notice anything. What's the 7 digit casting number?

paul burke
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Post by paul burke »

derrith wrote:I have two heads with the casting mark of m90. One is from an early 533, the other from my early euro 10:1 735i.

If you cross the head casting part number in realoem the m90 head was used in those two applications.
Sorry I can't get on the forums everyday but will check back as often as possible.

I'm trying to get to the bottom of this M90 thing as there seems to be an "early and late" version and I have the feeling that this is often over looked. Can you post a picture of the intake port and combustion chamber on the head marked M90. It should also have the same M90 marking under the camshaft below the last cam journal. Should also be the "702" casting.

Thanks,

Paul

shocka
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Post by shocka »

derrith wrote:
Mike W. wrote:
derrith wrote:I have two heads with the casting mark of m90. One is from an early 533, the other from my early euro 10:1 735i.

If you cross the head casting part number in realoem the m90 head was used in those two applications.
Where are you seeing the M90 designation? All the heads I've seen from Bavs up into the early 80's have the same casting number, 1 250 019, slightly later ones were 1 304 473, early US B34s seemed to be 1 277 358, later US B34s were 1 288 086, but Realoem doesn't recognize any of the numbers. The early number is especially interesting as there were at least 3 distinctly different castings with that same number.
The head I was looking at cross references here. M90 mark seen here:
Image
My early 533i had this stamp too.

browntown
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Post by browntown »

Paul, I called you a couple weeks ago about my m90 (1980 motronic version). I have it stripped down in preparation to send out to you after my wedding (June, I'm not allowed to make major car expenditures till then).

I'm away on business but I can take pics for you tomorrow night (wednesday). Mine has m90 cast in both places. The intake ports are the same as b34 I'm almost positive. I'll get pics when I get home.

Rich Euro M5
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Post by Rich Euro M5 »

FWIW: The cylinder head off my early 533i has the M90 casting as well. It's presently installed on the M30B34 in my '86 535i. When I had both heads side by side, visually they looked identical.

Rich

E21Adam
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Post by E21Adam »

This isn't exactly my area of expertise, but I thought the main difference between the early and later 3.5s was the bore and stroke. The m90 engines had a bore of 93.4mm and a stroke of 84mm. The later engines had a bore of 92mm and a stroke of 86mm. So, if all other things were equal, we would see the early cars with more horsepower and less torque than the later engines. If the later engines had a higher compression ratio, they would have even more torque, and a slight bump in hp. There are other differences between the engines though. The fuel/intake and exhaust (presence of catalyst included) are different, and I'd be willing to bet the camshaft has a different grind to complement those changes. So, there doesn't necessarily have to be a difference in the head casting; other differences can have the same effect.

slammin_e28
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Post by slammin_e28 »

^^M90 cam is also same as M30B35 cam. Aside from that, I think they're all the same head, M90 -> M30B34.

Nanajoth
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Post by Nanajoth »

From a 79' 635csi

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Last edited by Nanajoth on May 28, 2011 2:36 PM, edited 1 time in total.

Mike W.
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Post by Mike W. »

Ok, now that number is familiar and one I've seen on -33s. However I don't recall seeing the "R" in front of the number. I'll have to take a look and see, but I don't think I've got one of them. Oh, maybe I do come to think of it...

OK, back 10 minutes later, it seems I do have a couple. Both have an intake manifold on them, but neither in a car. The one on a block I took a pic of and it doesn't have the R, but does have 3.5 over to the side. I'm still not convinced it's anything special, but now I've got something else to waste time on.

Searching gaskets in Realoem it looks like the same intake manifold gasket for all pre B35 FI M30s, everything from US E12s to euro M90s to euro E28 525is'.

Image

paul burke
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Post by paul burke »

Thanks for posting the pictures.

This is the early small port head, '79, '80 maybe '81 it does not have "M90" in the casting as the later head has.

The manifold uses the same runner/head adapter as the E12 3ltr small port head.

So can someone post some pictures of the intake port area on a head marked "M90" . This head should have the intermediate size intake port like a B34.

At this point I'm not so sure all "M90s" were created the same, just looking to verify what I believe is going on here.


Paul

browntown
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more m90 love

Post by browntown »

I steam cleaned some of my 1980 motronic m90 from a euro 635csi for pics.

Here they be in high resolution:
https://picasaweb.google.com/jhbrown9/M ... directlink

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Mike W.
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Post by Mike W. »

Paul, is that what you need or more? I've got at least two I could tear into if need be, and I might just for good measure.

Mike W.
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Post by Mike W. »

The plot thickens, at least for me. I pulled the timing cover off one of my -473 heads and it has M30 instead of M90 under there. That's the one that also has 3.5 off to the right of the casting number.

Nanajoth
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Post by Nanajoth »

Mike W. wrote:The plot thickens, at least for me. I pulled the timing cover off one of my -473 heads and it has M30 instead of M90 under there. That's the one that also has 3.5 off to the right of the casting number.
Is the block stamped with an L?

paul burke
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Post by paul burke »

Image

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Comparing the intake port pictures pretty much confirms what I was thinking.

The early 93.4 x 84 "M90" is nothing more than a bored and stroked version of the M30 3ltr. This makes me wonder if there isn't a different designation for the earlier combination,the ETK even refers to this engine as an "M30".

Basically the short block dimensions are the same (early vs late) but at some time (around '81 model year?) there was a cylinder head change to the B34 style head. I have a complete early "M90" in the shop that I just tore down, now to see what it has for a camshaft.



Paul

wkohler
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Post by wkohler »

My M90 has the later intake ports like what Browntown posted.

7/80 M535i

Nanajoth
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Post by Nanajoth »

So would I gain anything by swapping my head with another?

TonkaTruck
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Post by TonkaTruck »

I have the possibility to buy a 79 Euro 635csi. My 86 535i euro "green" motor lost a head gasket.

If I buy the M90 can I swap the entire motor into my 5?

If that is an option, I can take pictures of the head if still needed.

2many6es
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Post by 2many6es »

Mike W. wrote:
Searching gaskets in Realoem it looks like the same intake manifold gasket for all pre B35 FI M30s, everything from US E12s to euro M90s to euro E28 525is'.

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CAREFUL - It's been a while but if I remember correctly, the M90 needs a special head gasket.

Again, it has been a while but if I remember correctly, the heads are the same but the water passages on the block are different and a "normal" head gasket will cover the passages on one side of the block.

I used to have some pictures. I'll see if I can find them and post them here.

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