I know this might be controversial for some of you, but here it goes anyways. I have a 83 240d that I am restoring just sent it out to have the rockers fixed. Car only has 134k on it. I bought this car with the intention of making it something crazy. So here we are I just bought a Cummins 6bt and a 5 speed transmission to go with it. Now the only hard part is going to be the radiator and intercooler, probably getting relocated to the trunk. My only fear is with the gearing in the rear end and if it will be able to handle the 300 hp we will be making. Are there any other gears that fit in that differential or will I need to change the rear end as well.

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That's extremely daunting, I wish I could add more.

Yeah it's bearly going to fit in the engine bay and stick out of the hood 2" with the drysump on the 6bt saves me 9" in height and we are lowering the subframe about 1 3/4" to try and get it under the hood but it probably won't be completely under

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That is a heavy friggin engine. Sounds like it will be fuggly. I have a 24 Valve and can't imagine that a 12 valve which is the same block would come close to fitting. Regardless, you will need to do more than move the intercooler. How much money and time to you have?

https://duiser.com/cummins-4bt-vs-6bt-2/

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

So a 6bt is only 300lbs heavier than a w123. And I'm taking my time with it don't care how long it takes or how much money

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Whoah there partner, you are headed for disaster.

The 6bt is closer to 1300#, a 617 turbo is less than 600#. The Transmission is probably a hundred pounds heavier than a 617 too. By the time you get everything strong enough for the cummins there won't be much of the mb left.

Not to mention the physical size ot the 6bt. I imagine it will sit a foot above the hood line and will be at least 8" too long to fit.

Better save the cummins for a truck. Heck, I wouldn't put it in anything less than a one ton of any other make than dodge.

If you want more out of the 617 you can upgrade the injection and turbo.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I know you meant a OM617 but the statement "a 6bt is only 300lbs heavier than a w123" is closer to accurate.

What are you going to use for a transmission? You say a "five speed" but what kind of a five speed?

I have no idea what/how you could possibly configure a drive train. We used Dana 70 differentials in the fleet of 6BT engined trucks I maintained and they often couldn't take the strain. Now granted, the trucks were used and abused by the drivers but I don't see the W123's differential/rear suspension set up capable to handle the engine's power.

It's your time and money. I'll be watching this thread just to see the progress.

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

So either the 5 speed that comes with the Cummins or one off off a Ford with an adapter plate. And anything can fit just depends on how much work you are willing to put in. And it will take time most likely a few years so be patient as will I. But I don't plan on keeping any part of the suspension anyways.

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I've worked on quite a few 4BT's using the old T19 transmissions. They used the 11" clutch/ bell housing set-up common to the 70's-90's Ford pick-em-ups. All the 6BT's I've worked on used the Clark/Eaton 5 speeds. Good tranny's but Lordy, they were HEAVY!

It oughta be quite the project.

Have you considered the 4BT engine instead?

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Yes I have but that's not as hard of a challenge I really want to push my ability on this and make it a leaving process of sorts I've doesn't engine swaps and little Fab work in the past but really want to push it on this. The 4bt only saves me on the front to back so I'd be able to put the radiator and intercooler but it will fit, just have to relocate them to the rear Wich is something I've always wanted to do.

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I think I'd have gone with one of the fairly plentiful gasser v8 w126's that are laid up dead, but all in all I approve.

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One more Radar Lover gone...
1982 VW Caddy diesel 406K 1.9L AAZ
1994 E320 195K

My issue would be it not fitting to the point of having to mod the hood and the hood not being closed and clean. The cooling system is huge on a Cummins. My truck (2500 only) has a Dana 80 in back and a Dana 60 in front. They are considered under sized by people that put down any power.

The trans (NV4500) needed work and I found a new surplus trans for cheap. That trans is much larger than the 722.303. They also need a larger input shaft than came originally installed and the 5th gear nut needs to be modified to not back off causing 5th gear to go out. There are many more trans configurations that have been bolted to that engine which expands possibilities.

And yes, I would have used a 126 because it has more room and more passenger room which I like at only 6'1".

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

This reads like this thread.

https://www.peachparts.com/shopforum/diesel-performance-tuning/390824-help-me-calculate-hp-dyno-must-have-been-wrong-modded-out-240d.html

A 6B is obscenely heavy, it is an industrial engine made for continuous power ( Vs a car engine where max HP is used intermittently ) The net says 1,100 LB dry but no info if that includes accessories. The trans can be a Chrysler Torque Flight, these are not that heavy.

Your front suspension won't last very long even with stiffer / taller springs, not to mention the car wanting to swap ends in every corner. The most direct route would be to drop MB body on a truck frame.

If you want a " Rat Rod " that only runs from trailer to the SEMA show floor, that is easy. If you want something that actually works, look towards another motor.

And please, don't be one of those idiots that think smoke = power and purposely smokes from every stop, see what Gale Banks has to say about smoke.

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CENSORED due to not family friendly words

5 bucks on it wont happen given the hot air already flowing from the OP and the total cluelessness apparent at trying to wedge that drivetrain into a 123. Going to be removing half the sheet metal on the car, and end up with a hideous monstrosity that A. Functions poorly as a running driving vehicle due to the 4000 fitment compromises, and B. Wastes a perfectly good HD diesel drivetrain.

Im all about engine swap projects, but some basic thought has to go into it first.

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