'89 325i + m30 + 4hp22 build

[CorvallisBMW]

Any updates on this?

[RedEye669]

Interesting. I've made zero progress on my swap because I'm having a hell of a time finding a manual tranny to fit an M30 (Saskatchewan not exactly being a Mecca of vintage BMW enthusiasts). I'd read that an M30 auto just wouldn't fit so I hadn't even considered it, but if this project works out I might just swap the auto in so I can enjoy the M30 while I keep looking for a 5-speed. Both my 325i and the donor e34 are autos.

[CorvallisBMW]

Anything can fit with enough use of a sledgehammer :)

[n3nyongmini]

Updates above. I lost my job right before Thanksgiving and have been a bit occupied trying to get re-employed.

[n3nyongmini]

OK moving along. Exhaust system is made up of e23 manifolds, e30m20 downpipes and a few odds-n-ends to get from the downpipes to the remainder of the front cat section.

Here's where I cut the front section:

[n3nyongmini]

Before getting the exhaust hooked up, I noticed that the rack-to-oil pan clearance was tight. Perhaps only a mm or two:


I slipped some large nylon spacers between the mount arms and the stock m20 motor mounts. The spacers are really just large nylon washers about 3mm thick, and did the trick. I tried 6mm spacers, but I didn't have enough thread on the motor mount stud (I didn't feel like turning them over - that might have worked, but I like the raised " button" on the bottom).

With the additional 3mm; I am guessing the rubber in the mounts will settle over time and the 6mm spacers may come in handy:

[travish325]

Why not just use the m20 harness? Much easier than rewiring the m30 one.

[n3nyongmini]

Why not just use the m20 harness? Much easier than rewiring the m30 one.

Well, in my haste to liquidate the remains of the m20, I wasn't thinking and sold the injector harness with the rest of the parts, so I really only had half an m20 harness.

It seemed to be about the same amount of work either way. Maybe not.

[travish325]

I think only a few wires need extended on the m20 harness all the plug ins are the same though. Most swaps Ive seen the m20 harness is used. Either way cool project!

[n3nyongmini]

Here are the two m20 downpipes with added lengths. The two sections are "reversed" from the original placement on the m20, where I used the short stubby section with the flex to get clear of the firewall. I brazed an o2 sensor bung onto the straight section since I cut out the portion that had it originally. I am thinking there is a way to use it. "Next Time". The o2 will only be reading from the front 3 cylinders, but I don't think that's really going to be a big deal.


Oh I forgot to mention: I used the e23 manifolds since the e34 ones were too close to the mount arm. That was before I picked up a welder, so I'll be looking for a way to use the larger e34 manifolds and downpipes "Next Time"..

[n3nyongmini]

Just about ready to fire it up....I had to fab a bracket for the kickdown cable.

[e30trooper]

Very nice!

[G-Man the Visionary]

Hi, thanks for doing this swap, it's the only one i can find... I'm staring mine now as well... '89 325i vert auto (dead m20)... found a running 735il (b35) and am getting the complete engine/ ecu and bell housing from it... ebay mounts from england are ordered... stahl headers for a 635 already in the garage and crossing my fingers that they fit without mods...

The only questions I have are...
-are there different models of bell housing from the m30?
-will the m20 harness work out ok with everything (other than extending injector wires)?
-any electronic hookups i need to know about on bell housing that could cause a problem?
-any other hick ups i should know about?

Other than those things, it seems like a plug n play kind of deal, right?
Thanks,
David

[G-Man the Visionary]

oh, i forgot... what have you done with the cooling system?
thanks again

[Smash9002]

Awesome swap! I have dreamed before about doing somthing similar. I read somewhere, maybe even in this thread, that someone offers high-stall speed torque converters for m30's. The idea of a "muscle car" e30 build with an m30 backed by an auto with a high-stall converter is pretty tempting!

Have fun!