MyE28.com

Hello guys,I finaly got around to pulling the engine/tranny out of my euro 635csi. At first I was planning on dropping it as is into my 533i but after talking to my buddy Cspargo from bigcoupe.com I decided to make a few changes. Although the engine ran great in the e24 with great power and perfect idle, it was suggested to me that I should ditch the L-jet and upgrade to Motronic 1.3. From my research so far it seems like there are a few things that will need to be swapped. First, the banana style manifold needs to go as well as the throttle body. On the m90 the throttle is operated by linkage and not by cable. I was considering swapping the throttle body only but it seems like most of you think that the newer intake manifold flows better. From there I have to address the the vacuum advanced distributor. My buddy is saying that I should remove the timing chain cover after which it should be a straight swap for the forward facing distributor. I still have some doubts about that but he has more experience than me with these engines so I guess we'll see. Next on the list come the engine mounts-they seem to be a direct swap between the m90(steel ones) and the m30 ones (aluminum). I haven't done and measurements yet but it seems like the m90 will drop right in with zero modifications to mounting points/custom mounts. Pretty much this is where I am at right now. While I was having my coffee in the morning looking at the engine, I was thinking that may be I should swap the camshaft with one from a b35. I also read the crank from a m30 will slightly stroke the m90 but I am still reading on that. Overall, I have all the parts laying around and it's simply a matter of elbow grease. Please, feel free to share any knowledge about this and tips. I'll be taking detailed pics as I go through the process. Thank you

this is the motor waiting on a pallet in my garage.

you can see the throttle body and the linkage mechanism which is actually on the other side compared to the m30b34/35 motors

This one is completely removed. I actually had to remove the valve cover in order to pull the throttle body out

This is a pic with the valve cover removed. It doesn't look too bad but it's not sparkling clean either. Btw, the engine has 78k on it

engine pic with the harness wiring removed


Tonight or tomorrow I'll swing by my buddy to pick up some goodies such as the newer intake, tb, timing chain cover with distributer and etc. I'll be back soon...

Its a little dirtier under the valve cover than it should be, but if the cam is in good shape, who cares.

It wont run the same with the motronic style intake manifold. I bet you'll lose a little top end and gain a lot of low-mid.

hmm, it already has insane torque down low and I am not sure I want to gain more while losing top end. Anybody else can confirm this? Thanks

99% of the heads in the junkyard look like that, really dark, some are super clean that look like they have been rebuilt or some look tan.

well, the head is not as dark as it looks in the pics. I am still contemplating if I should pull it off and clean it up. This will mean new headgasket and ect and I am not really sure if it's worth since the motor ran so well before removal.

If the HG isn't blown, leave it alone.

What's an M90?

The M90 is the large bore short stroke M30 that was available in early euro 635CSis, E12 M535is, and some E23 735is. The block is the "M49" code and is essentially the same as the blocks used for the M88/3 engines from the M1. This is all info from the original and updated versions of Jeremy Waltons 6 Series Enthusiasts Companion. They share the same bore as the M88/3, S38B35, and S14B23 - 93.355mm, and have an 84mm stroke instead of the 86mm stroke of the M30B34 and M30B35. Total displacement is 3453cc instead of 3430cc.

I have owned an M90 powered E24 and I can attest to the awesomeness of this engine. They feel quite a bit different than your standard M30. They seem to rev more freely and pull to the redline very willingly. My M90 wound up in an '84 325e and was sold to a very happy customer in Oregon!

My dad has an M90 powered 633CSi (swapped of course) and it runs very well with over 225,000 miles on it. The thing absolutely walks away from my '87 535is!

turbodan wrote:If the HG isn't blown, leave it alone.

Really? I would assume now is a good time since everything except the head is coming off Anyway. Just another step or two to get the head off and replace the gasket. That way you have some assurance on exactly when the gasket was replaced and have a number of worry free miles ahead of you.

Then again, I'm no expert and turbodan may be speaking from more experience.

It just seems to me that with 78k miles, the headgasket is probably either original or was replaced once in the late 80's/early 90's. If not replaced now, how is one to know that you won't have to be replacing it in another 20k miles?

That said, I'm still nowhere near an expert.

I'd go ahead and change the HG while the engine is out of the car... The larger bore generally means that these engines burn through gaskets much more easily than a standard M30. If I am remembering correctly, there are only about 4.5mm separating the cylinders.

It wont hurt to replace it, but these head gaskets aren't a maintenence item like clutches or brakes. You can kill them if you overheat the motor, but other than that theres no reason for one to fail.

If theres nothing wrong with it now, you can't do any better than that by taking it apart, and you could possibly do a lot worse.

I agree with Dan, if it isn't broken don't mess with it. As Dan said the HG isn't a maintenance item like other parts. I'd pull the plugs and confirm no evidence of steam cleaning. The photos don't show any evidence of H2O getting into the oil.

Rich

I've seen more M30 head gaskets leaking due to coolant eating away the gasket around the passages. I'm sure that motor had maybe 1 or 2 coolant flushes depending on how many thermostats or water pumps its been through.

If it's been sitting any amount of time, go ahead and put a water pump on it. It'll leak a month if not a week later.

I have to ask this question even though I feel pretty stupid for it: But would a B35 head fit/work on an M90 block? Is the difference in bore enough to make it not work? Or even if it did bolt on would the increase in combustion chamber size decrease the CR enough to make the end result not desirable?

ElGuappo wrote:I have to ask this question even though I feel pretty stupid for it: But would a B35 head fit/work on an M90 block? Is the difference in bore enough to make it not work? Or even if it did bolt on would the increase in combustion chamber size decrease the CR enough to make the end result not desirable?

not a stupid question at all. I was wandering exactly the same thing but I am leaning towards "no". I lot of people want the m90 block so they can bolt on the m6 head on it so I think this pretty much answers our question....

I ask because I have a B35 head on the 535 I bought last year, a couple of B35 intakes sitting around, I can grab B35 exhaust manifolds any time.....adn I think I still have access to an M90.
sooo............

ElGuappo wrote:I have to ask this question even though I feel pretty stupid for it: But would a B35 head fit/work on an M90 block? Is the difference in bore enough to make it not work? Or even if it did bolt on would the increase in combustion chamber size decrease the CR enough to make the end result not desirable?

I think it would be less than a stock B35, those have those odd shaped pistons, but effectively some crown to them, resulting in a 9:1 CR. M90's had flat top pistons, so it would be somewhat less than 9:1. And if it's the M90 I think you're talking about, after this time without a head on it (I think the head was missing the last I saw it) I wouldn't go near it. It would need pistons and a bore.

Hmmm, I did not recall that motor missing the head, so thats a shame. Last time I saw it, it was intact....

Oh well, perhaps I shall go the 'bug' piston route as well in my current block.

So whats going on with this M90?

ElGuappo wrote:Hmmm, I did not recall that motor missing the head, so thats a shame. Last time I saw it, it was intact....

Oh well, perhaps I shall go the 'bug' piston route as well in my current block.

So whats going on with this M90?

It must be my memory, I haven't been to Rancho since July, I think it was. As I've mentioned a bit to you, I've been kind of busy lately

Maybe it was the engine in general that had a lot of aluminum corrosion on it, the intake etc.

Yeah that motor had alot of funk and 'fuzz' on it....Looked like it had been sitting for quite a while. But Craig had taken the injectors/fuel rail, so thats been open to the elements for a while now....

Well, it's been a couple of weeks...in the meanwhile I got a complete m30b35 with harness,ecu,afm and etc...a few questions:
1. b35 cam-will it fit?Is it an upgrade?
2. Intake-will it fit since it's a little bigger than the b34. Will I have to port match the head to it? Is it worth it?
3. Any benefit in power with the 1.3 motronic? Will I bump into any issues converting from Ljet to motronic?

This is getting interesting. I ran the cartest program on my car with the specs of the stock m90 and it put me in under 6sec 0-60. If I am able to get a little more out of it before dropping it in I should be in the mid 5s 0-60 and mid 14s 1/4 mile(with the 3.25 diff). Sweet....thanks for your input guys....

maximapitko wrote: This is getting interesting. I ran the cartest program on my car with the specs of the stock m90 and it put me in under 6sec 0-60. If I am able to get a little more out of it before dropping it in I should be in the mid 5s 0-60 and mid 14s 1/4 mile(with the 3.25 diff). Sweet....thanks for your input guys....

First, that program is a little optimistic it seems, no way in hell a stock M30 with a 3.25 diff is gonna give you that. Add at least a second to each time, if not more.

Second, using Motronic 1.3 will give you much better everything over L-Jet, including a rudimentary self-diagnostic ability.

maximapitko wrote:This is getting interesting. I ran the cartest program on my car with the specs of the stock m90 and it put me in under 6sec 0-60. If I am able to get a little more out of it before dropping it in I should be in the mid 5s 0-60 and mid 14s 1/4 mile(with the 3.25 diff). Sweet....thanks for your input guys....

Kyle in NO wrote:

maximapitko wrote: This is getting interesting. I ran the cartest program on my car with the specs of the stock m90 and it put me in under 6sec 0-60. If I am able to get a little more out of it before dropping it in I should be in the mid 5s 0-60 and mid 14s 1/4 mile(with the 3.25 diff). Sweet....thanks for your input guys....

First, that program is a little optimistic it seems, no way in hell a stock M30 with a 3.25 diff is gonna give you that. Add at least a second to each time, if not more.

Second, using Motronic 1.3 will give you much better everything over L-Jet, including a rudimentary self-diagnostic ability.

Well, I agree with you and that's why I am talking about a m90 just like the title of this topic clearly states. This motor is putting out almost 40 more hp than a m30 does. An intake from a b35, a motronic 1.3 conversion, m5 flywheel and possibly the b35 cam(still trying to find out if it's any more aggressive than the m90 one), chip and slightly bigger injectors, I am hoping to get closer to 235hp. The 533i's weight is around 3000 pounds last time I checked which will make it lighter that the e36 m3 which puts out 5hp more and accelerates 0-60 in 5.5s(http://en.wikipedia.org/wiki/BMW_M3#Nor ... can_models) So, I'll end up with a lighter car that puts out the same power as the e36 m3...I don't understand what's so funny or unbelievable about my previous post?

Run the car when you get it put together. Then we'll know. If I were you I wouldn't count on that kind of performance. Disappointment is a bummer.

The car won't run a 5.5s 0-60. End of story. It won't happen.

I'm putting down 320 whp (and 335rwtq) with a 3.46 rear end and a 265 getrag, and according to the g-force (or g-tech or whatever the hell the thing is called) meter I'm only in the low 5's (5.2-5.3 if I can get the tires to hook-up correctly in first).

Well, I guess we'll have to wait and see what turns out at the end...now I am reading up on the b35 crank into the m90-supposedly it will stroke the motor a little. Any input at all on building a hybrid like that? Also, is the b35 cam better than the m90 one?

I believe the cams are same...should both be 264 but I'm not sure. The b35 cam is definitely a 264 though.


You need custom pistons if you use the B35 crank. Its been discussed on bigcoupe.com multiple times.