W123 OM648 Project - PeachParts Mercedes-Benz Forum

BirthdayBenz · #1 02-07-2022, 10:25 AM

I’ve begun an ambitious project which I hope to finish. I see two possible outcomes. The first is having a pretty unique, quick, and fun to drive W123 and the second is learning why I’ve only see one other car with this swap.

Why not an OM606?
Engines are very costly and rare then have unknown miles ($3k or so)
Mechanical injection pumps are also costly ($2-3k)

I’m early in this project and am aware of the following challenges I’ll need to overcome in regards to the swap. I’m sure I’ll find others.

1. Engine mounts
2. Transmission/mount/shifter
3. Electronics (ecu/CAN,etc)
4. Vacuum pump (OM648 has no vacuum)
5. Fuel pump (OM648 requires electric pump before mechanical)
6. Cooling
7. Intercooler

Engine Mounts. I’m sure I can fab something up. I’ve got a bunch of mounts around. Some from an SL some from the W123, Some from G500, Some out of the CDI.

Transmission. My W123 has a 4speed manual. I wont be using that. Even if an adapter was fabricated I’m sure it would explode eating over four times the HP and torque the little 240D left the factory with. I wont be running an automatic.

What plan to run is a six speed GS6-37DZ transmission from a diesel 1 Series BMW.

I think it fits in the transmission tunnel of the W123. I'll need to have an engine mounted to it before I can be sure on the positioning

How does a BMW six speed transmission connect to an OM648? Dieselpump UK.

Electronics. This is a probably the issue which prevents this swap from taking place. I've seen the OM648 swapped into Land Rover Defenders and boats in Europe so it must be possible. I've purchased a harness from an OM613 and a stand alone ECU from Blacksmoke Racing.

I have a complete donor car from a Copart auction which was less expensive than any OM606 I've seen for sale. It runs and drives great. I almost have the OM648 ready to come out.

87tdwagen · #2 02-07-2022, 08:20 PM

Sounds like an interesting project. Is that Blacksmoke ECU already programed for stand alone operation or does it still require programming? I would imagine that all of the engine sensors will remain in use in the ECU, but auxiliary inputs O2, ABS/ESC cruise, will be a challenge or need their programming adapted to avoid limp mode.

Are you thinking about moving the ODB port over to the w123 to maintain some code retrieval capability?

BirthdayBenz · #3 02-08-2022, 05:42 AM

The Blacksmoke ECU is already programed to be stand alone. I exchanged some emails with them and we discussed what I'm trying to do.

In addition to power and grounds, the inputs I need to wire in will be the accelerator pedal and OBD port for code retrieval and monitoring. All of the auxiliary inputs have been deleted/adapted. Other than swirl and egr, every sensor that connects to the main engine harness will remain.

h3ffe · #4 02-08-2022, 03:21 PM

Very cool. Good luck as you embark on this journey!

3. Has Black Smoke Racing deleted the EIS? How does the starter motor get the authorized crank signal, if not via CAN?

4. The W220 OM648 cars had a vac pump.

5. Fuel pump - I'll get you the part number and a pic of how my car has it set up.

6. Cooling - There is no room for fans in between the stock OM617a radiator location and the OM648. I'm having a custom radiator, AC condenser, and e-fans/shroud made. This involves:
* Deleting the auxiliary fan on the front
* Pushing the new shorter and wider condenser up where the aux fan was
* Pushing the the new shorter and wider radiator up under the core support, approx where the condenser was
The e fans will sit where the radiator does now, leaving ~1.75" clearance to remove the e-fans/shroud for any front dress work.

7. Intercooler - I'm having custom boost piping and an intercooler made as well. The intercooler will sit in the inner fender, similar to an oil cooler on an OM603 car. No room for the stock IC in the stock location, much less an upgraded one.

Not mentioned yet - you'll need to swap to a front sump oil pan and pump, from an OM613, M104, OM606, or OM603. The Land Rover/Land Cruiser/Patrol/G Wagen swap guys all need your rear drop sump and pump, so that should be no problem to trade someone, or sell outright.

VaiFanatic · #5 02-08-2022, 04:14 PM

Oh this is cool. Definitely following along.

BirthdayBenz · #6 02-09-2022, 06:05 AM

Quote:

Originally Posted by h3ffe

Not mentioned yet - you'll need to swap to a front sump oil pan and pump, from an OM613, M104, OM606, or OM603. The Land Rover/Land Cruiser/Patrol/G Wagen swap guys all need your rear drop sump and pump, so that should be no problem to trade someone, or sell outright.

Well this stinks. Yeah... I measured things after I read your post and that stock sump is going to be right on top of the crossmember. I need another engine stand and a bigger garage. Too bad the M113 pan wont fit. I have two of those...

What pan are you running?

BirthdayBenz · #7 02-10-2022, 06:20 AM

Removed this big beast yesterday. I'm amazed that I didn't spill a single drop of oil on my concrete pad. I'm used to working on the om617 i suppose.

Trying to figure out where to put everything. I've no space in my "2 car" garage for the W123, and all these engines, transmissions and parts I'm accumulating.

How much does the OM648 and 722.6 weigh (LBS)?

dieselbenz1 · #8 02-10-2022, 11:55 AM

Sweet I'm building a shed for my parts lol

BirthdayBenz · #9 02-14-2022, 10:21 AM

Not much progress to report. Pulled EGR related things off of the manifold then learned to use Illustrator in order to draw up some EGR delete plates. Sent the drawings off to SendCutSend.com this morning for laser cutting out of 6061 aluminum.

BirthdayBenz · #10 02-16-2022, 12:38 PM

Continuing disassembly. I've got over $100 in gaskets coming. Going to fix everything that is leaking or I think might leak while this thing is not in the car. What a pain it would be to do that oil cooler gasket when this is in the car.

EGR related things.

VaiFanatic · #11 02-18-2022, 03:10 PM

Kinda thinking about doing something like this to that 300SEL I've got. Certainly plenty of space, and the adapter kits for manuals seem reasonably priced, haven't checked the availability of the transmission you're using, but I assume they're easy enough to come by. Or I may just grab one of their kits that works for the M103 and go from there.

BirthdayBenz · #12 02-20-2022, 07:26 AM

Quote:

Originally Posted by VaiFanatic

Kinda thinking about doing something like this to that 300SEL I've got. Certainly plenty of space, and the adapter kits for manuals seem reasonably priced, haven't checked the availability of the transmission you're using, but I assume they're easy enough to come by. Or I may just grab one of their kits that works for the M103 and go from there.

Compare to the 617 and even 603, this engine runs amazingly smooth. I was excited to hear the turbo spool up driving the CDI up the hill of my driveway. I think this would be super cool in a w126, but I would think manual conversion could be more trouble than its worth. The transmission I have was very inexpensive. Also being from a diesel car it has better gearing for the CDI engine compare to something from a gasoline car. But also, the adapter plate kit is the most expensive part of this swap.

This swap would probably be simpler in the w126 chassis than it's going to be in the w123.

I've thought of doing this in a W108 also. Some sort of ratty looking one making 500hp

BirthdayBenz · #13 02-20-2022, 07:42 AM

I decided on an OM606 pan. Counting bolts on the M104 pan, the pan dropped for the sump one bolt hole before the 606 pan which would have set it forward about 50mm. I think I have a pump coming from one of the clubgwagen guys. Fingers crossed there. The accessories and drive belt on the CDI engine are very close to front the edge of the pan. Maybe only 60mm out. I sure would like to use the puller fan from the CDI but not sure if I'll have room. Wonder if I could reverse the thing and run it as a pusher fan on the other side. I had a parallel flow condenser and sanden compressor on the 617. Not sure if that is going to stay. I'd forgo AC for a CDI swapped W123 anyhow so it's not a big deal.

VaiFanatic · #14 02-20-2022, 11:32 AM

Quote:

Originally Posted by BirthdayBenz

Compare to the 617 and even 603, this engine runs amazingly smooth. I was excited to hear the turbo spool up driving the CDI up the hill of my driveway. I think this would be super cool in a w126, but I would think manual conversion could be more trouble than its worth. The transmission I have was very inexpensive. Also being from a diesel car it has better gearing for the CDI engine compare to something from a gasoline car. But also, the adapter plate kit is the most expensive part of this swap.

This swap would probably be simpler in the w126 chassis than it's going to be in the w123.

I've thought of doing this in a W108 also. Some sort of ratty looking one making 500hp

The manual conversion is definitely worth it for me. I HATE automatics. I've already made a manual pedal set by cannibalizing the parts from a W201 pedal box for my 500SE, and can do the same again fairly easy enough.

My '96 F-350 that I bought from the original owner was on its third E4OD automatic, and I quickly swapped it out for a ZF-5 with a transfer case to also make the transition from 2WD to 4WD. I've also completed an auto to manual swap in my '98 Durango with the 5.9 Magnum V8. No manual swap isn't worth whatever troubles it may bring

I can fabricate a lot of what's needed, but my shop time has been reduced by increased work (I work IT) and the fact that I just became a dad last month. DieselPump's kits are reasonably priced (compared to Rennsport, anyway) and I wouldn't mind just paying the piper to get the job done a little quicker.

I am thinking, however, for the sake of not having to deal with too much in the way of electronics, going with a 606 to replace the M103. If my 170S (4cyl) were a 220S (6 cyl), with the longer hood/engine bay, I'd stuff the M103 in it, haha.

The goal would be a peppy, long-wheelbase sedan, that can get fantastic mileage and do well on long trips across the country.

w123fanman · #15 02-20-2022, 09:17 PM

I'm considering an OM647 for a W123, seems to be closer to the spirit of a 300D. Was your weight with oil in the engine and trans?

Either way, very interested in how this turns out. I will pick up a 612 harness for this build.