Our friend Dan Woods stopped by CX Off-Road in Paraguay to talk to owner Javier about his 1959 Unimog 404. Javier built the Unimog to compete in rally racing such as the Desafio Cordillera (Cordillera Challenge) with the shop’s other Unimog, a tan stock 1974 406 model. They chose Unimogs over a modified truck because of their strength from the factory. The dark 1959 404 originally came with a 2.2 L Mercedes M180 inline-six which produced around 80 horsepower. Javier decided to swap the motor with a 2.5 L M123 inline-six from a Mercedes W123. The engine is stock except for a Fueltech EFI and Holley Avenger throttle body which helps the motor produce around 150 horsepower and 150 lb-ft of torque. The rest of the Unimog’s powertrain has remained stock. Javier did upgrade the front suspension with Bilstein shocks to handle the tough off-road races.
More photos of the tan 1974 Unimog 406.
Source: CX Off-Road FB page via Dan Wood
The original 80 HP will take this truck about any where, albeit not very quickly.I wonder how much double HP/torque would increase top speed because of gearing. There would probably be little danger of mechanical breakage. I’m not sure if they made faster axles for the 404, but if there was a faster gear available it could be put to good use, in this application.
Good point. It would be interesting to see a side-by-side comparison of the modified 404 and stock 404.
Mine will hold 62 MPH just under red-line. If I could find a surplus F1 motor capable of 18,000 RPM, I could explore the limits of barn-door aerodynamics. Usually if I’m in a hurry, I take the VW Golf.
EFI and. Carb? How does that work?
Good catch. It should be “throttle body”. I have corrected the article.
A Mercedes diesel would also make a great swap.
So how successful has this been?
Good question. Unfortunately I forgot to ask about that.
To get the answer to that question I stopped by the shop yesterday. I wanted to show them that they had been featured on this site. One of the owners (who was really excited) said that it is faster than the stock Unimog. With respect to ‘success’, I think that is hard to define, when I asked he said they were competing against trucks from around 2015. I don’t think they really fit in a class, that’s why they run ‘Turismo’. I mean, there’s no class for heavily modified agricultural rally vehicles :). I didn’t ask about trophies etc because I felt uncomfortable prying too much, I don’t think winning is the main thing here – although it’s one of the goals. If they wanted to win, maybe they would focus on a different vehicle, I don’t know. But as for being a one of a kind vehicle that is probably really useful to have around, as well, I’m guessing they would call it a success. It looks like they have a lot of fun at the events they go to.
Thanks Dan for stopping by the shop again. Your probably right about the build being equal parts competing and having fun.
What size Continental tires are you running with? I like the ‘tall,skinny’ look
I do very little off-road and just cruise to the shows and markets with the 404 radio
How do I get that EFI for my 1968 404 ?
Hi what efi kit you use for this engine