Want to build a Gen1 DodgeCummins for towing, up to 35000 lb GVWR, what engine should I build?

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The Tow Rat

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1991, 1995
Engine
5.9 12V VE Pump, 5.9 12V P Pump
Hey all,

I have a 1991 Cummins 5.9 2500, which I would like to build up as a 35,000 lb GCWR tow mutant.

I will be doing a bed delete, Spicer S-111 or some similar rear axle, frame mounted gooseneck, and BIG HONKIN' DISK BRAKES at all 4 corners. I really want a 6 speed manual, but I'm not sure what transmission to use for over 900 lbs ft. of torque. Will dive down that rabbit hole in a future post.

Regarding the 5.9, which is my topic for this post, the first step (of course) will be to ditch the VE pump and get a a P-Pump. Beyond that, all will be fairly standard 12V performance hop-up which I will not bore you with right now.

Here are my questions for this post.

1) I think I know the answer to this already, but I would like to hear what others have to say about it: 12V vs 24V.

2) I think I know the answer to this too, but... 5.9 short block vs 6.7 short block. What do people think?

Regards,
The Tow Rat
 

Dean2

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If you are going to tow 35,000 lbs, build yourself a Peterbuilt. Nothing about a 91 2500 was designed for that weight, from frame, to springs, to brakes, transmission and everything else. That pickup is far too light to handle that weight at highway speeds.
 
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The Tow Rat

The Tow Rat

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1991, 1995
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5.9 12V VE Pump, 5.9 12V P Pump
Yes, Dean2 and 392DevilDog, you are both absolutely right; the engine is actually the easy part!
But as to whether a Pete is needed... no, I don't really think so. Take a look at the '21-'24 Ram 3500HD. That is what gave me the idea. Ram touts a rather stunning -41600- lb GCWR for the new 3500HD trucks!

Admittedly there's a lot I would need to do to my Gen1 2500, to emulate a '21-'24 Ram 3500HD. But hey, have you looked at list prices for a new 3500HD? I got my Gen1 5.9 for $3200. A new 3500HD starts at $48,735 and that doesn't include the Max Tow Package. The difference is more than $45,000. For that, I can buy a lot of nice heavy duty parts!

I'm not worried about the rear axle, or the springs, or the brakes. I can find dually class 5 sized rear axles with 10,000 lb and up GAWR and nice big disk brakes with vented rotors, from a couple different possible sources.

Some things that are going to need sorting out, are the transmission and the frame. For transmission I'm initially thinking Fuller FSBO9406A six speed. But I don't know how much it weighs, and I don't know if it will fit.

Regarding the frame, yeah you are right, that is going to be a challenge. The new 3500HDs box in a big section of the frame in the back. I could do the same thing. But I think I am leaning towards using the existing frame unmodified (avoids welding on it, which is good because its heat treat won't be compromised) and adding a bolt-on DOM tube frame for reinforcement. Since I am comitted to a bed delete, there will be plenty of room to add something like that.

I haven't thought about the front axle much yet. A newish beam axle out of a class 5 truck, again with disk brakes sized for that application, would be the obvious first go-to. But I'm not sure how I would go about adapting the springs and steering. It might have been easier if my truck had a 4x4 front end on it.

Hmmm... Maybe I need to get a 4x4 frame and do a frame swap, so that the front suspension will be closer to what I would need to adapt a heavy duty beam axle?

Regards,
The Tow Rat
 

Gr8bawana

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2017
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6.7 CTD
Yes, Dean2 and 392DevilDog, you are both absolutely right; the engine is actually the easy part!
But as to whether a Pete is needed... no, I don't really think so. Take a look at the '21-'24 Ram 3500HD. That is what gave me the idea. Ram touts a rather stunning -41600- lb GCWR for the new 3500HD trucks!

Admittedly there's a lot I would need to do to my Gen1 2500, to emulate a '21-'24 Ram 3500HD. But hey, have you looked at list prices for a new 3500HD? I got my Gen1 5.9 for $3200. A new 3500HD starts at $48,735 and that doesn't include the Max Tow Package. The difference is more than $45,000. For that, I can buy a lot of nice heavy duty parts!

I'm not worried about the rear axle, or the springs, or the brakes. I can find dually class 5 sized rear axles with 10,000 lb and up GAWR and nice big disk brakes with vented rotors, from a couple different possible sources.

Some things that are going to need sorting out, are the transmission and the frame. For transmission I'm initially thinking Fuller FSBO9406A six speed. But I don't know how much it weighs, and I don't know if it will fit.

Regarding the frame, yeah you are right, that is going to be a challenge. The new 3500HDs box in a big section of the frame in the back. I could do the same thing. But I think I am leaning towards using the existing frame unmodified (avoids welding on it, which is good because its heat treat won't be compromised) and adding a bolt-on DOM tube frame for reinforcement. Since I am comitted to a bed delete, there will be plenty of room to add something like that.

I haven't thought about the front axle much yet. A newish beam axle out of a class 5 truck, again with disk brakes sized for that application, would be the obvious first go-to. But I'm not sure how I would go about adapting the springs and steering. It might have been easier if my truck had a 4x4 front end on it.

Hmmm... Maybe I need to get a 4x4 frame and do a frame swap, so that the front suspension will be closer to what I would need to adapt a heavy duty beam axle?

Regards,
The Tow Rat
Someone who supposedly has this much knowledge on this stuff wouldn't be here asking for others opinions.

1698449890683.png
 

Dean2

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Someone who supposedly has this much knowledge on this stuff wouldn't be here asking for others opinions.

View attachment 530844
Started to think exactly that, it is why I quit responding. On top of that, if he is serious there is clearly no way to talk sense to him, he already knows it all.
 
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The Tow Rat

The Tow Rat

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5.9 12V VE Pump, 5.9 12V P Pump
Troll? Don't know where that is that coming from... Guys this is only my 4th post on the forum, or something?

Wow, is someone just allowed to ask honest questions here?

Anyway give me a break, I'm a long time Cummins Ram owner and I have been towing with stock trucks for decades, but this is the first time I've contemplated modifying one of my trucks specifically for towing heavy. So I am bound to ask stupid questions... Par for the course.
 

rzr6-4

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With enough time/money/effort anything is possible, but with your list of parts swaps including pretty much the entire thing, sound to me like you are essentially buying a whole new truck and just doing a cab swap on it with the one you have already, as that is pretty much the only thing not on your list.

Therefore.... just buy a 4500/5500 and just do a cab swap to make it look like your gen1.
 
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The Tow Rat

The Tow Rat

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1991, 1995
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5.9 12V VE Pump, 5.9 12V P Pump
Anyway I'm in kind of in a hurry to figure out how to build a Cummins powered truck for $15k-$20k-ish that can pull a long 6% grade at 55 at 35000 lb GCW. And to do all that without hitting crazy EGTs or killing the transmission.

Thanks again @Dean2 and @392DevilDog, for pointing out that modding a Gen1 is probably going down the wrong rabbit hole. Part of my motivation was avoiding electronics and smog, plus I was just thinking to start with what I already have, but I agree that plan doesn't really make sense.

So now I have my eye on a '04-1/2 Cummins 3500 dually with NV5600, tow package, and 12200 GVW rating.

I talked to Cody Albrecht at Superstick Transmissions. He says he can build me an NV5600 that can handle 1000 hp so I think that takes care of the transmission.

Now my questions is, 5.9 24V vs 5.9 12V. Forget the tumble swirl discussion... what I really need to know is which will work better for my application.

Obviously, if I was going to keep it registered in Ca, 5.9 24V would be the only answer because of smog, but I'm thinking as a backup I could maybe get it registered through a family member in a non-smog area in Wa State.

I want to build the engine with a really flat torque curve limited at less than 800 lbs-ft, and putting out 450-ish hp at 3000-3200 RPM, to take it easy on the transmission.

My question:
Which platform is better to build a 450-ish hp 5.9 with less than 800 lb-ft of torque, 12V or 24V?

Gr8bawana,​

Character attacks for their own sake usually don't accomplish much in forums.

Regards, and thanks again,
The Tow Rat
 

Scottly

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I haven't heard anyone mention frame issues, but I'd have to think that needs to be a consideration. It's your money.
 
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