The comprehensive DOHC engine swap thread.

[Jason89i]

1. Will the auto ECU and harness work? I read several things about the 525i harness working but not specificly the auto harness and ECU.
2. Why can't I use the stock E master and booster? I thought I read you can but it seems everyone is replacing them.

1. yes, the ecu will work. you will want to remove the auto trans ecu (separate item) from the wiring harness. i also cut all the wires off the harness and capped them.
2. the E master will work. the E booster is too large in diameter and will hit the intake manifold. use the e21 320i (or ix booster) with the E master.

cheers, jason

[325Projectz]

1. Will the auto ECU and harness work? I read several things about the 525i harness working but not specificly the auto harness and ECU.
2. Why can't I use the stock E master and booster? I thought I read you can but it seems everyone is replacing them.

1. yes, the ecu will work. you will want to remove the auto trans ecu (separate item) from the wiring harness. i also cut all the wires off the harness and capped them.
2. the E master will work. the E booster is too large in diameter and will hit the intake manifold. use the e21 320i (or ix booster) with the E master.

cheers, jason

You'll have to change out the MC for it to work with the iX booster because of the different bolt patterns

[Ryan Stewart]

More than that, its a double booster so half of the MC fits INSIDE of the booster. If you tried to put a regular MC on there the rod from the pedal wouldnt reach.

Yes the E30 master will work with the E36 slave, you can also install an E30 slave. If its a non M3 E36 slave it will work JUST like the E30 slave.

[joshh]

So I was looking on "realoem.com" and found that the E28 M5 and the E28 533i have the same engine mounts. Earlier in the thread it was mentioned that if you use the 533i mounts that you will need 5mm spacers. Either I'm missing something or the 5mm spacers are not needed.

Part#'s:
Right: 11811175592
Left: 11811175591

[joshh]

Heres another odd thing.
The Ix Booster part # is 34331161486.
The 320i and 325E are the same part #: 34331157416.

[DEV0 E30]

^ Interesting. I'm still a little ways from worrying on the details...

However, I think I'm going to put an E36 rack into the car designated for an M50 swap at the same time as the swap, Zionsville has the 2.7 lock ratio one (Z3?)...however it's pricey. Good news is it's the entire kit...

$449 - 3.25
$549 - 3.0
$549 - 2.7

Is it worth it for another $100 bucks for the 2.7 if I were to buy from Zionsville at all? I know they are overpriced but for all the materials from one place... can I justify it?

[Addissimo]

^ Interesting. I'm still a little ways from worrying on the details...

However, I think I'm going to put an E36 rack into the car designated for an M50 swap at the same time as the swap, Zionsville has the 2.7 lock ratio one (Z3?)...however it's pricey. Good news is it's the entire kit...

$449 - 3.25
$549 - 3.0
$549 - 2.7

Is it worth it for another $100 bucks for the 2.7 if I were to buy from Zionsville at all? I know they are overpriced but for all the materials from one place... can I justify it?

I did the same thing and its totally worth it. However, I got my rack off of car-part.com for $200 and just got the zionsville cd and ordered the $20 in parts for a grand total of $245 I wouldnt pay them 550 for that shit, if you have a vice and a dremel you're golden.

-Addis

[DEV0 E30]

Cool, thanks Addissimo.

How do you like it?

[Graham325]

I am about to buy a m50 from a 92 525, the car is an automatic and I know I have to modify the wiring harness a little, but I have the feeling the harness will be in not very good shape, can I use a harness from any obd1 m50? or do I need to get a new one, can I get a new one from a 5 speed if possible? Also the car doesnt include the dme, can I use any type or does it have to be the same as the origional Thanks - Graham

[Addissimo]

As far as the wiring harness goes- you'll be fine with the one that comes with your motor. I don't believe the automatic part makes any difference with the e34 harness... Its just 6 inches short and makes the ecu mounting a bit difficult (ask me how I know).

You need an ecu from either a 92 325 or 525 as your engine is vanos free, that was the only year they came without vanos in the states.

-Addis

[joshh]

I've gotten started on removing the motor from the 525i.
I've decided to mount the ECU right where it was on the 525i in the 325. I will need to modify the box the ECU was in but I wanted to find out where some of you mounted your ECU. I don't remember anyone earlier in this thread mentioning where they mounted it. Thanks.

[Brew]

Everyone I know of who has done the swap mounts the ecu in the stock location above the glove box.

I wouldn't risk putting in the engine bay. Fried ECUs are common on e36s because the compartment they are in tends to leak.

[joshh]

Ah, didn't know that thanks.

[joshh]

Has anyone done any type of shiming on the motor to get rid of the 10* of tranny twist? Like putting washers between the motor mounts and the motor mount arm? Is this even a good idea?

[Brew]

No. The M50 is designed to run at the 20 degree angle.