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Unimog 404.111 build

After months of researching and searching, I finally got my hands on what I believe are the best available intake and exhaust manifolds for the OM617A.

The most power MB got out of the OM617 was in the experimental C111 concept cars built in the late 60s/early 70s. The motor broke 9 different diesel & gas world records.
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That OM617 produced 228HP, and was capable of 200+ MPH. (So this is my Ultra4 motor now :laughing:). The C111s are interesting to read about, they got their extra power from upgraded manifolds, an intercooler, bigger turbo and a modified cam (which I’d love to find the specs on).
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That intake manifold is the same as what’s on some 1975-76 W115 cars. I was pretty excited to find one and get my hands on it. Unfortunately, it didn’t play well with the 404’s engine bay. It could have worked, but I’d have to move the firewall near the passengers feet and would need a ton of work to get an intercooler in there. So I kept looking for this other exhaust manifold I only read about….

In the 90s MB came out with a light cab over van and AMG designed an OM617 for it. It had a very similar intake to the one above but it didn’t swing out from the block as much so it was taller and the intake was at the front vs the side. Two big bonuses for fitting in a Unimog's engine bay. The one I scored off Germany’s eBay a month ago showed up today and you can really tell the difference.
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While I can’t find many specs, I’m counting on the fact that these were designed by AMG 30yrs after the ones in the C111 vehicles that they will have equal or better performance. 🤞🏼

The exhaust manifold pictured are found in some 79 300SD models cars. Also hard to come by because they have the largest primaries of any OM617 exhaust manifold and no egr components to disrupt flow.

aaaaand my stainless pie shapes showed up from Summit today so I can finally start finalizing the downpipe size/shape. If things line up the way I hope, I could actually have a straight straight-pipe exhaust. :smokin:
 
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Interesting read. I sware the concept looks like a Delorean. Or maybe I should say a Delorean looks like it. 200 mph out of 228 hp sounds optimistic.

Edit, your motor looks beautiful!
 
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Been spending more time insulating the shop and getting ready for hvac out there, I did get some time this weekend to grind down the compressor housing for clearance and get the intercooler setup in the space I wanted, just need to make a bracket to mount it.

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Next I'll get the first few feet of the exhaust bent and send the manifod, turbine housing and first few feet of exhaust out for ceramic coating. :smokin:
 
I cant wait to see how that manifold fits under the doghouse, I got the frozenboost intercooler with the inlet and outlet pointing the same direction but I like the way you went.
 
Badass build. I’ve been trying to acquire my buddies mog for years(he doesn’t drive it). I’d like to tear it apart and see how it’s put together. He has an om617 in it from when they made kits for them. I believe the engine is clocked some to help with clearance, but I’m not sure. When I get it, I’ll post pics.
 
Fantastic thread, allot of information, Went down the rabbit hole of 404 stuff, definitely watching this thread.
That cab is definitely in better shape then the Chev cab I've got slated for my 404 axles :laughing:
 
Finally getting back at it now that the summer heat and my honey-do list is almost gone. Still need to get the motor mounted and fired so that’s top of the list.

Spent the summer ordering stuff to work on this winter, more parts showed up today…
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As soon as I get my hands on a second steering axle I’ll be rebuilding them with all new bearings/gaskets/seals from Expidetion Imports. Replacing the weak MB portal boxes with 74Weld’s boxes. Also using 74Weld hubs to convert to disc brakes using Spidertrax rotors, Wilwood calipers & pads. :smokin:

Only thing missing is the hydro steering parts from RadialDynamics but I need to get this stuff on and them back under the rig before ordering that stuff.

I loath rebuilding axles, but look forward to rebuilding these.
 
Those are some good looking parts, I didn't know 74WELD still made portal boxes for MB axles, Those a special request thing now?
Can't wait to see em on the rig, After fighting with my drums on the 404 axles the other day, I wish I had a set of those Hubs :lmao:
 
Those are some good looking parts, I didn't know 74WELD still made portal boxes for MB axles, Those a special request thing now?
Can't wait to see em on the rig, After fighting with my drums on the 404 axles the other day, I wish I had a set of those Hubs :lmao:
They're a CNC shop. A "special order" of something they've made in production volumes before is stupid easy to do.
 
Those are some good looking parts, I didn't know 74WELD still made portal boxes for MB axles, Those a special request thing now?
Can't wait to see em on the rig, After fighting with my drums on the 404 axles the other day, I wish I had a set of those Hubs :lmao:
They still make the boxes and hubs upon request. Like arse_sidewards said, they are just a file that sits on their network and they can print them anytime.

I wasn't going to do the brake conversion right now because their hubs are not cheap. Worth it, but not at my stage of the build. Luckily I got the used copper ones for a great price, way less than 1 new one.

Anybody want to guess who the copper coated hubs previously belonged to? :laughing:

I ordered the boxes from Quinn at King of the Hammers in Feb. Off-road stuff is not 74Weld's primary business and what off-road stuff they have been doing has been heavily focused on Jeeps, Broncos and Toys in the past 2 yrs. I'm happy for the guy to have a boom'n business right now ... but with that them having time to get these made and shipped can take a bit. Worth the wait tho.
 
Send me the cab. In 3 months I'll send it back as a crew or extended. :flipoff2:
 
Can build a bed like that, too. I have 8' bed sides.

Not hard to extend the frame or torque tube either.
 
I took the whole week off between Christmas and NYE just to work in the shop… today was the first day I was able to get out there to do much :shaking:. I did play with my new 3D scanner and plasma table though, I can see this being a lot of fun and helpful.

Today I put them to use cutting custom exhaust hangers. Stock 404 exhaust is very small diameter and crosses from one side to the other which I also didn’t want.
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Once I had that mocked up, I was able to run exhaust from the turbo to that piece of straight pipe.

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It was a bit tricky to route it under and around parts of the cab but it worked out. The drivetrain pivots where the exhaust ends in the pics, I’ll use a flex pipe there and run the rest once I figure out placement of the rear fuel tank, battery, etc. I used 2.5” because I read a lot about 2.5 being good for up to 400HP (many say more). I’ll be 225hp if I’m lucky, hope I don’t regret not going 3”.

I don’t have weld plugs to tig up the exhaust (also not the best at tig) so I’ll take them to the shop in town this week to finish weld them.

Next up I’ll be scanning the front/drivers side of the block to chart the avail bolt holes to make a PS Pump mount.
 
Since that portion of the exhaust is done it’s time for ceramic coating. 404s are known for getting hot in the cab since your sitting on both sides of the motor. Exhaust manifold, turbine housing and the exhaust that’s pictured above. Should help keep some heat away from the cab.

I’ve been playing a lot with my new 3D scanner and plasma table, so I decided to redo my motor mount to include the hydro pump for the steering. I should have done with the first motor mount I made but it wasn’t until it was made and in place that I thought about putting the pump next to it.

3D scan of the front of the block with the portion of the factory mount I kept:
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New motor mount and pump mount designed in Fusion 360:
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Mount cut, welded and installed:
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I have new pedals coming this week and will set the cab back on and see what space I’m working with just behind the mount. As long as that’s all clear next steps will be getting the motor ready to run when the exhaust gets back.:smokin:

I’m loving the hell out of the plasma table and just want to design/build stuff.
 
Purdy.
Did this one have the OM352 stock?
My club is looking into picking up an Unimog 425 as a tow rig which according to the current owner has a busted engine.
We ain't skeered to swap it for whatever but I am concerned about the pneumatics and hydraulics.

 
Are you gong to use a 90 pointed down on the pump outlet? Looks like a tight fit.
I’ll be using two sweeping 90s to run that line down the side of the motor like this

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If that's too sharp, I don't think it will be, I can clock it 90* and have that line point up before swooping back. Was trying to save space to the right of the pump with this orientation
 
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