Preparing for my m30 swap.. Help me choose the best combo

[Jb325is]

Alright.. Well I've done a little research here and I think I have a pretty good grasp on what I need and what I don't need, but I do need some help from you guys that have actually done the swap. The original plan was to pull my 10.5:1 cr 3.6L m30 out of my e34 and run that in the e30, but I was worried about taking on multiple engine swaps and the e34 is my daily driver. Luckily, a friend of mine is giving me a killer deal on a m90/265 combo out of his e24. This adds to my growing collection of m30 stuff, so tell me what I should use for my swap into an '88 325is

This is what I have:

-complete L-jet m90 with unspecified cam
-complete '92 m30b35
-complete '88 m30b34
-'88 535i 5 speed driveshaft
-'88 535i 5 speed trans crossmember
-Getrag 265

What I need:
-Engine mounts, isn't there a member who sells them?
-'86-'87 325e driveshaft
-m30 harness, 179 ecu?

My questions are:
-Does the m90 use the same mounting holes as the b34?
-I read that the m30/260/'87 325e driveshaft will bolt up using the e28 trans crossmember, will this still work with the 265?
-What needs to be done with the harness/ecu? I read on here that the m20 harness plugs up? Is this true? Also, I don't have any spare m30 ecu's, should I be looking for a 179?


As of right now, I'm planning on running the b35 head, with some work, on the m90 block with the b35 crank. Also planning on getting e21 runners for the m90 intake, having it extrude honed and adapting it to the b35 head. Has anyone done this before? I've read somewhere that it can be done with a different style injector and the m90 fuel rail but I haven't seen the m90 stuff yet to compare.

Input/suggestions/experience all appreciated!

[euroshark]

First of all, GREAT engine choice! I think this will make you the second member in the US to build an M90 powered 335i. *cough* Mine was the first one I know of... *cough* :pimp:

I used the early stamped steel transmission crossmember and it had to be modified slightly. I'm not sure if the aluminum E28 piece will work, but I'm 99% sure the E30 M3 piece will work.

The M90 uses all of the same mounting bosses and such for the motor mounts and bellhousing as the B34, so no issues there. You will need the B34 upper timing cover and the correct rotor adapter for the end of the cam, but those are both commonly available parts... I've got both floating around in the garage if you want them.

The M20 harness will work but you will have to lengthen a few of the wires for connectors near the front of the engine. Shouldn't be a big deal. Definitely go with the 179 ECU, apparently the 150 ECU will also work but is kind of a turd.

Joe Funk - "Funkmasta" - is the man to talk to for mounts.

I wouldn't waste time with the old style manifold, and if you are converting it to Motronic it's going to cause huge headaches with the injector setup since L-Jet injectors are COMPLETELY different than Motronic injectors as far as mounting goes. I would also advise against the B35 head since it is going to drop the compression from 9.3:1 to about 8.5:1... This is a step in the wrong direction unless you are planning on throwing a turbo on it, and personally, I think the M90 is a rare enough engine that it shouldn't be subjected to turbocharging. That's the purist in me... If you are planning on going turbo, sell me your M90 block and use the proceeds to buy an 8:1 compression B34! I've even got a good low compression block for you!

Anyhow, this should be a cool swap, keep us updated.

Edit: The driveshaft length might be a hard one to answer. I had to have mine shortened by 1 3/16" using the E30.de mounts in the furthest back position, but I had the front section of a 635CSi shaft. Hopefully someone else will have a good answer to this issue.

[Jb325is]

First of all, GREAT engine choice! I think this will make you the second member in the US to build an M90 powered 335i. *cough* Mine was the first one I know of... *cough* :pimp:

I used the early stamped steel transmission crossmember and it had to be modified slightly. I'm not sure if the aluminum E28 piece will work, but I'm 99% sure the E30 M3 piece will work.

The M90 uses all of the same mounting bosses and such for the motor mounts and bellhousing as the B34, so no issues there. You will need the B34 upper timing cover and the correct rotor adapter for the end of the cam, but those are both commonly available parts... I've got both floating around in the garage if you want them.

The M20 harness will work but you will have to lengthen a few of the wires for connectors near the front of the engine. Shouldn't be a big deal. Definitely go with the 179 ECU, apparently the 150 ECU will also work but is kind of a turd.

Joe Funk - "Funkmasta" - is the man to talk to for mounts.

I wouldn't waste time with the old style manifold, and if you are converting it to Motronic it's going to cause huge headaches with the injector setup since L-Jet injectors are COMPLETELY different than Motronic injectors as far as mounting goes. I would also advise against the B35 head since it is going to drop the compression from 9.3:1 to about 8.5:1... This is a step in the wrong direction unless you are planning on throwing a turbo on it, and personally, I think the M90 is a rare enough engine that it shouldn't be subjected to turbocharging. That's the purist in me... If you are planning on going turbo, sell me your M90 block and use the proceeds to buy an 8:1 compression B34! I've even got a good low compression block for you!

Anyhow, this should be a cool swap, keep us updated.

Edit: The driveshaft length might be a hard one to answer. I had to have mine shortened by 1 3/16" using the E30.de mounts in the furthest back position, but I had the front section of a 635CSi shaft. Hopefully someone else will have a good answer to this issue.

Wow, thanks!

On the m30 timing cover and rotor adapter.. I'd assume that would be the same on a b35? My b34 is still in my e28 and the stock b35 from my e34 is sitting on the floor in my garage, so obviously the b35 stuff will be easier to get to.

As for the b35 head v. m90 head.. does the m90 have the bigger valves? The motor in my e34 has a b35 head that was shaved, with m90 pistons and b35 stroke and is at 10.5:1 compression, so that is what I'm hoping for with this motor. I'm going to get ahold of the guy that built the motor in my e34 to work on this one.. Supposedly he works at Sunbelt racing engines here in GA now so it should work out well (if you haven't heard of sunbelt they make some serious badass n/a s5x motors)

Current motor:


I guess we'll just wait and see about the driveshaft.

[euroshark]

Interesting... So they put the 93.355mm pistons in a B35 block? From what I have heard, M90 pistons in a B34 / B35 block have to have the tops shaved 2-3mm because they protrude from the block with the longer crank. Still, at that point I don't see how it's possible to get 10.5:1 compression even with a shaved head since the M90 is 9.3:1 compression with the pistons level at the top of the block and smaller combustion chambers... Unless they didn't shave the pistons, but then they would have to clearance the cylinder head.

I'm confused.

Do you have any documentation on the build of that motor? I'm not doubting it but I am genuinely curious.

[Jb325is]

Interesting... So they put the 93.355mm pistons in a B35 block? From what I have heard, M90 pistons in a B34 / B35 block have to have the tops shaved 2-3mm because they protrude from the block with the longer crank. Still, at that point I don't see how it's possible to get 10.5:1 compression even with a shaved head since the M90 is 9.3:1 compression with the pistons level at the top of the block and smaller combustion chambers... Unless they didn't shave the pistons, but then they would have to clearance the cylinder head.

I'm confused.

Do you have any documentation on the build of that motor? I'm not doubting it but I am genuinely curious.

Yep.. Pretty sure the pistons weren't shaved either. It was originally an m90 block, but for some reason they swapped everything over and bored out a b35 block because of the different mounting points. I can call the guy that built the motor tomorrow and see what he says.

[euroshark]

If they swapped everything over including the crank and rods and just bored the B35 block then you have the original displacement of an M90 (3453cc) and the only difference in compression would be from the shaved cylinder head. If you have the longer crank you are going to be at 3535cc just like an S38B36.

I don't want to rain on anyones parade but I really am curious to hear what the guy says. I don't think you can shave the head enough to get 0.8 extra compression points without the valves hitting the pistons, especially with the bigger B35 valves.

[Jb325is]

My parade won't be rained on over .8 compression points :) Here is what he told me about the motor:

M30b35 Head
- Port matched
- New valve guides, new valve seals, and 3 angle valve job
- New rocker shafts, rockers and all related hardware
- BMP Rocker locks
- BMP 290 degree camshaft
- BMP adjustable cam gear
- BMP double valve springs and hardened keepers

M30b35 Block
- 10.5-1 Compression
- Bored from 92.5mm (M30b35 specs) to 93.4mm (Euro M90 specs)
- Used the longer (M30b35) 86mm stroke (as opposed to the 84mm M90 stroke)
- Decked, honed, line honed
- Crankshaft and connecting rods balanced

[E30SPDFRK]

I want that cam and cam gear! BMP doesn't have it on their site, is it special order or nla?


As for your swap, I believe the e30 factory transmission crossmember would be the one to use with that transmission. It's what I used with my b35/260 combo, not that that matters to you.

There is a place near me that will shorten/lengthen your driveshaft for only $90 in case you can't find the correct one.

[Doughnut]

g265 with unmodified pressed steel cross member:


modified pressed steel cross member:


...As you can see, this part of the swap is cake. You must elongate the holes on the bracket so that it will bolt to the chassis then get a piece of 'C' section cut it to a short length, drill a hole for the rubber transmission mount and weld it on!

Love the idea of the m90.... Badass!

[kronus]

Nice.. at the rate you're going, you'll be done even before I have my engine!

PM'd you about mounts

[Lurker27]

Good info, posting just to save it. :)

[Jb325is]

I want that cam and cam gear! BMP doesn't have it on their site, is it special order or nla?


As for your swap, I believe the e30 factory transmission crossmember would be the one to use with that transmission. It's what I used with my b35/260 combo, not that that matters to you.

There is a place near me that will shorten/lengthen your driveshaft for only $90 in case you can't find the correct one.

I thought I saw the cam gear on their site recently, but the cam does seem to be NLA.

g265 with unmodified pressed steel cross member:
*

modified pressed steel cross member:
*

...As you can see, this part of the swap is cake. You must elongate the holes on the bracket so that it will bolt to the chassis then get a piece of 'C' section cut it to a short length, drill a hole for the rubber transmission mount and weld it on!

Love the idea of the m90.... Badass!

Thanks for the pics! So that's a stock e30 crossmember? I'm going to try a couple different ones that I have laying around just for future reference, but your method looks simple enough. One less thing to worry about.

[speedhop]

I don't know if I'd use the stock e30 crossemember, although people have come up with some inventive ideas on using it. You could just not worry about modifying anything incorrectly and use the m3 crossmember with the g265. It's a stock part used specifically for the purpose. You do have to buy m3 mounts, which again is used specifically for the purpose. Just playing devil's advocate :)

[RickSloan]

alot of great info in this thread, can't wait to see this monster complete.

I'm also really curious about this stroker. From the sound of it, it seems like a cheap(er) stroker solution. What kind of power is it producing?

all of those parts are more available then the s38 options correct?

[Doughnut]

So that's a stock e30 crossmember?

No, it's the crossmember from an e24 (stock e30 g260 crossmember does not work with the g265) You can use your stock e30 transmission rubber mounts with this setup!

I think they used this same bracket in the manual e28's too.