E34 V12 M73 Conversion Got Questions

[Dmeister]

Hey everyone, here is the lowdown. Ive been wanting to do a V12 conversion into my E34 for a while now, and it looks like its gonna happen! I have an opportunity to purchase a M73 Engine + Auto box + Computers and basically everything I need, all at a good price, and only 60,000 miles!

So now to my question - I know about how many computers there are to run the engine and such, and the transmission computer, but what else am I dealing with here? I might have to transplant the whole car lol, but yeah just wanna get it starting and running.

Thank you all so much in advance

[E39Chris525i]

Prepare for . Also, you will need a new cooling system and maybe a new drivesaft, all sorts of ecu's and the labor is gonna kill you if your not doing it yourself. If you have a shop do the work for you, then try to get all the other parts on your own so you can save some $$$. Expect at least $7K for the whole job. If you do this, post pics.

[Efterlyst27]

I have a 37,000 mile M70 V12 with autobox and ECUs if youre interested PM me.

[russiankid]

Not worth it. If you're doing it for the cool factor, then go ahead. If you're trying to get more power, then wrong drivetrain.

[Dmeister]

Hey guys, thanks for the replies. Yeah moneys not the issue lol. 7 Grand sounds pretty darn good for what I'm getting! But yeah might end up spending more no doubt. So yeah, I'm an engineering apprentice, and also done time at automotive school, always been into cars, and modifying them. I have a keen interest in cars and engines that are either notoriously unreliable, complicated, rare, overlooked, misunderstood, expensive, feared, revered, uncharted territory, and trying to make it work.

Yeah damn the M73's electronics are pretty tricky and thats the only thing that gets me. Probably not worth using mucking around with the M73 electronics then. Might just go with standalone ECU as I can loose the drive by wire, and all the intrusive electronics, and only run one ECU, with the bonus of tunability, it'll be a sure-shot job. For the ECU right now im looking at a Haltech, and running semi sequential for the injectors, and wasted spark for the ignition. First thing will be to get the engine starting and running.

For the transmission I'm thinking a manual + adapter plate job, or if I can find a 6 speed manual from an 850i that would be awesome. Flywheel would have to be custom made. So for the cooling ill be using an aluminum radiator and expansion tanks, electric fans. Yeah not really looking at going fast and furious. But yeah its the perfect motor for what I'm after. Its reliable, smooth, refined, has plenty of torque, quiet, and puts down power without a fuss. 326hp is plenty much for me, as its gonna be a street car that id like to drive everyday.

[Richard454]

If you are looking at different electronics to run the M73 is alone going to be at least $3k- Check out this-it uses (2) GM V-6 units-


I have seen some use the 735 mechanical throttle-but the First ever drive by wire is a very reliable piece (nothing like the Toyota's !!!)

I have also seen twin chevy 6cyl dizzys replacing the BMW's and a carb replacing the fuel injection.

The M70 would be a better choice as far as electronics- Only about 17 wires are needed from the X20 & X21 connectors (including 7 for the throttle) using the original 3 computers.

Transmission- I've heard less than 900 850's came w/ the 6 speed- The cheapest I've seen around was $2700 - used and almost $5k for a NOS. And add in the flywheel and clutch and you are easily looking at another grand.

The kit car guys are using an Audi trans axle for mid-engine kit cars so an adapter is not impossible- just a lot of work. No other BMW motor shares the same bellhousing bolt pattern.

I'm current working on a swap myself-but stayed away from the M73 because of the OBDII electronics (Pre & after Cat O2 sensors etc) but do like the roller lifters used in it. I bought a complete running car- went through the wiring diagram- clipped wires and made sure it would run w/ minimal wires connected BEFORE I even considered pulling it and rewiring it...

Richard

[Roger45]

Looking for a manual shift contoller for a 4HP24 trans out of a 750i (V12). I know they makes these things but would like to know if anyone has a contact number or website that points me in the right direction. Level 10 used to sell these thing but now don't.

I'm building a 1930 Model A Ford Coupe with a BMW V12 in it.

Motor already runs with two Chevy HEI distributor and a stainless steel homemade intake manifold.

Email me with shift controller information if you have it. roger.stegall@eur.army.mil
Thanks,


Roger

[Grimmjar]

You have mail.

[E36 V12 Seattle]

There is a random reference on MegaSquirt to somebody running an M70 as two M20's. They appearently started bank 1, and then turned bank 2 on. Not an ideal solution...

http://www.msruns.com/viewtopic.php?f=91&t=9741

I recently bought an M73. Planning on using 2 megasquirts with a setup similar to the BMW (two ECU's, two MAF sensors, two TPS sensors, two crank angle sensors, etc)

I want to drop the distributors, but I still may use the rotors for some type of cam angle sensor, in lieu of a crank angle sensor.

It's new territory but I don't think it's as techinically challenging as a lot of people think. In school we did a custom megasquirt setup for a CBR600RR motor on our SAE formula car. We ended up with 8 sequential fuel injectors, and electronic ignition, on a motor that spins to 14,000 rpm.

Doing a batch fire on the fuel injectors (as I believe BMW does stock), and electronic ignition seems doable. Just expensive and time consuming. I'd love to setup a sequential system with the fuel injectors, and I think that's possible, with the new MegaSquirt 3 box. Anyway I'll start a thread once I get deeper into the motor.

So far just taking everything apart. Impressed at how well made these things are. Some great looking/functioning castings in these things. It's also funny how the EPA ruins everything. Oil in the intake manifold (to heat up the air after starting to reduce emissions)...

[TheMonkey]

...I recently bought an M73. Planning on using 2 megasquirts with a setup similar to the BMW (two ECU's, two MAF sensors, two TPS sensors, two crank angle sensors, etc)

I want to drop the distributors, but I still may use the rotors for some type of cam angle sensor, in lieu of a crank angle sensor.

It's new territory but I don't think it's as techinically challenging as a lot of people think. In school we did a custom megasquirt setup for a CBR600RR motor on our SAE formula car. We ended up with 8 sequential fuel injectors, and electronic ignition, on a motor that spins to 14,000 rpm.

Doing a batch fire on the fuel injectors (as I believe BMW does stock), and electronic ignition seems doable. Just expensive and time consuming. I'd love to setup a sequential system with the fuel injectors, and I think that's possible, with the new MegaSquirt 3 box. Anyway I'll start a thread once I get deeper into the motor.......

I've been using an MS3 with X board on a V8 with full sequential fuel and ignition. It can handle a V12 in semi sequential fuel and wasted spark. That would be a lot easier setup, wiring, and tuning than trying to use 2 units.

[sharpee325]

The M70 would be a better choice as far as electronics- Only about 17 wires are needed from the X20 & X21 connectors (including 7 for the throttle) using the original 3 computers. ......


Richard

I have an M70- i've been considering all the options for making it run without the ENTIRE 183lb wiring harness. This is the first reference i have found hinting that the original computers can be used with minimal wiring from the original wiring complex of the 750il it was taken from. Richard?!?!?! can you go in depth about this "17 wire~X20~X21" idea? thank you so much....
Steve

[Richard454]

Hey Steve-

I pulled out my notes- this is for PRE-facelift build before 9/90

Bold wires needed

If you need anything else- just email me richard454 at comcast dot net

on the X20 connector
PIN 1 Blue Diagnostic not used
2 Black/white oil level I not used
3White/Black fuel/cluster not used
4 Brown /Violet temp/cluster not used
5 Brown/Green oil switch to gnd not used
6 Green/White +12v 15A O2 sensor & E box fan run and start
7 Green +12 coils/ need run and start
8 Black /Violet anti theft not used
9 Black engine speed output tach not needed to run
10 Blue /Yellow Oil lever II not used
11 White /Green Diagnostic connector not used
12 Gray to check engine light -bulb needed to run (from cluster) wire hot- ground other side of bulb
13 Green/Violet fuel pump II 7.5A ignition switch run & start
14 Black /White speedo sensor not used
15 Brown/White +12V run & start key park trans switch
16 Yellow/White Diagnostic not used
17 White /Violet diagnostic not used
18 Black/Yellow +12 for starter
19 Green/Blue not connected/not used
20 Brown/Yellow temp & cluster not used

Here's what I have for the pedal assembly-

[B10 BITURBO]

IMO.. if using the 5HP30,,,, there are 2 ways to do it,,,, oem ECU with some hard work to get it to work in a proper way

or use a TOP standalone system that can read the gazpedal DK motors,, the ,,LANGUAGE,, between engine ECU and transmission ECU etc etc,,

using a manual gearbox with standalone will always be the easiest solution ,, i am confident of that

both Richard and my self are running standalone,, he have a self made manual transmission,, i am using the REAL one,, G560,, with oem clutch flywhell etc etc

the most simple way if running manual,, is naturally the oem G560,, but using the BMW V8 gearbox + V12/V8 adapter that is available on ebay,, is with out doubt an alternative i would look for,, ,,you can use the V8 flywheel,, clutch etc etc and the cost is not that high,, just remember that you must also use an adapter between the flywheel and clutch,, incl, pilot bearing in the same thickness as the engine/transmission adapter is

[1956fhah]

HALLOW RICHARD I NEED YOUR HELP I HAVE BMW V12 M70 ENGINE I NEED COMPLETE WIRRING SYSTEM AS YOU DO IN THE PICTURE MY EMAIL
h.m.h.1956@outlook .com price + shipping thank you hameed