The comprehensive DOHC engine swap thread.

[dineshblack]

Hi ALL!

Hoping this board is still active.
What I have,
1990 BMW e34 520i, M50b20 NV.

What I have done
Complete M50b25TU swap with harness, ECU and meter.
Car cranks but does not start.
Theres fuel through the injectors, theres spark, compression is good.

Have no clue what else to diagnose as all the sensors have been changed. Could there be a wiring issue I am missing? all grounds checked.

[mjweimer]

I think I might've lucked out with the flywheel I bought. It's the E21 323i lightweight M20 flywheel 11221264517 that is all ready missing the ring on the back that the normal M20 flywheel has (which I assume is the part that needs to be machined down in the first place since the back is nearly flush with the ring gear). We'll see if the starter on the ix M20 will work I guess. Anyone know if I need to get a euro 323i starter to match that flywheel?

If my memory is correct, the E21 and E30 M20 flywheels have the same ring gear tooth count/profile. The E30 starter is half the weight and smaller than the E21 starter so several folks have done that swap as an upgrade when rebuilding their engine. I think you are good to go.

[dylhaus]

I think I might've lucked out with the flywheel I bought. It's the E21 323i lightweight M20 flywheel 11221264517 that is all ready missing the ring on the back that the normal M20 flywheel has (which I assume is the part that needs to be machined down in the first place since the back is nearly flush with the ring gear). We'll see if the starter on the ix M20 will work I guess. Anyone know if I need to get a euro 323i starter to match that flywheel?

[Northern]

I'd say if you're already paying for the bulk of the setup/balance work, you may as well get the thing lightened.

[dylhaus]

In regards to using the single mass m20 flywheel with the G260 trans on a S50 swap, when shaving it down, is it best to just shave down the area hitting the rear main seal bolts, or should I just take down the whole back side a few mms and re balance?

[TeXJ]

Hello everyone. My first post! I'm sorry if this has been covered bet there's SO much to sift through. My daughter and I are doing a M50 swap in a 1991 318is with a G240 gearbox in it. I see a lot of talk about G260s but can we use the G240?

Thanks.

https://www.google.com/search?q=m50+swap+with+a+g240&rlz=1C1ASVB_enUS847US847&oq=m50+swap+with+a+g240+&aqs=chrome..69i57j33i299l2.7216j0j7&sourceid=chrome&ie=UTF-8

first response:
http://https://www.r3vlimited.com/board/forum/e30-technical-forums/24v-engine-swaps/m50-52-s50-52/215116-m50-with-a-g240

[chilone]

Hello everyone. My first post! I'm sorry if this has been covered bet there's SO much to sift through. My daughter and I are doing a M50 swap in a 1991 318is with a G240 gearbox in it. I see a lot of talk about G260s but can we use the G240?

Thanks.

[e30strokr]

so I go a SETA 88 325 (e?) with G260 transmission which I believe has the dual mass FW.... is it safe to use or should I be looking into getting a 325I Flywheel?

[fastestbox]

Anyone have any experience with fitting a Z3 exhaust manifold on an e30?

[968Reckless]

Amazing, thank you!











Parts list would be great for reference.



Absolutely necessary to shave down the m20 single mass flywheel? What happens if you skip this?

Mock everything up and you will see the problem.


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[schmidty]

Yeah, it won't fit if you don't. At least not when using the g260

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[amcp]

I believe the flywheel rubs the block if you dont.

[Panici]

Below is from the swap notes I have culled from r3v 24v swap posters who were gracious enough to post their experiences. Unfortunately I did not save the posters information for credit where it is due.

Amazing, thank you!

Also had a machine shop shave down the m20 single mass flywheel. I'd have to look up how much they shaved off.
Clutch and TOB were both M20 parts as well as most of the other components needed. I can get you my parts list if you want as I also went in and refreshed some of the transmission components.

Parts list would be great for reference.

Absolutely necessary to shave down the m20 single mass flywheel? What happens if you skip this?

[schmidty]

Just an FYI on the FPR, The early model e39 528i cars came with an fpr on the fuel rail like the m50 motors. I just got one and will need to install it on mine. I am obd1 and wish it was obd2.

Honestly, right now I'm looking for the quickest easiest way to get it running and I figure an external FPR would be easier than installing a new fuel rail.... but maybe I'm wrong...

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[TeXJ]

Just an FYI on the FPR, The early model e39 528i cars came with an fpr on the fuel rail like the m50 motors. I just got one and will need to install it on mine. I am obd1 and wish it was obd2.