5 ton 12v 5.9 repower?

[acme66]

Now don't start screaming. I have a 250 855 in a m923 that has munched a liner. I will not be putting an unknown 855 take out in despite how cheap they are because this is a back up to my commercial unit and it has to be a known reliable. So I was going to reline and re piston the block. Or... I can drop a 5.9 12v turbo with an auto out of a 94 Dodge. Same money. Drop the 855 and Allison and just build a drive line to the transfer case. For what I am doing I don't care a lick about stock, or even resale value for that mater. I put about 12,000 miles yearly on the truck hauling passengers on tours, no where near rated capacity or heavy off road. I am under the opinion that I could do it, save a bunch of weight, pick up a mess of MPG, knock off a ton of maintenance costs and have a truck that pulls/drives as good as my beasts do now. They are purpose built machines, not combat assault vehicles, well not any more. Never a haul above 5000lbs.

I have spent a lot of time quietly reading about duces repowered with them but haven't found (not that they don't exist) a 5 ton. Seems like such a simple solution, what am I missing?

Ken

 

[sandcobra164]

Stock 6BT 12V makes about 400 to 440 ft lbs of torque. The NHC 250 in these trucks makes 685 ft lbs. Even with that, it's a little on the sluggish side empty. I know you can upgrade the 5.9 to compensate but that'd be my only concern.

 

[74M35A2]

You would be cutting engine displacement by 2/3. Throw 15,000lbs into the bed of the Dodge it came out of, and that is what it would drive like. I would use a blown motor as a chance to up-power, not down. You can probably find a good used running Cummins 400hp 855 for the cost to rebuild your NHC. People nearly give away running NHC's. If you were really on a budget, you could replace the bad cylinder with a good used one from somebody here giving away their 250, and just be out a new top end gasket set.

 

[swbradley1]

I don't think you see a lot of creative power plants in 5-tons because the original motor is more than adequate.

The big thing you lose right off the bat is torque and depending on which 5.9 you lose HP as well.

 

[Bandit02]

I think with a 12v you'd burn alot of fuel to move a 5 ton. Even with twins, injectors and a done up P7100. I wouldn't trust the dodge auto behind it for that amount of weight lol.

The Cat 3406B I got lined up into mine is a huge repower project but 425 HP stock is worth the work.

You can have my NHC250 + Allison for free if you want it, like brand new after the rebuild the military did on it. You just have to come get it.

 

[my76fj40]

You could get the power out of the 5.9, but would the tranny hold it with even an empty 923? Is there enough "horsepower hours" in the 5.9 running at a level that would be satisfying?

I have been telling myself that if for whatever I need to repower I would look for a BigCam 350-400, you could keep the drivetrain that is rated for the load, would still need to figure turbo and intercooler plumbing, but the engine should last till were all too old to drive. Any conversion I have ever done was always a list of compromises. Trick is finding the best compromise for your use.

Slow typing... Bandit has a great plan.I would run up just for the spare. Going to be in NW MT very soon.

 

[74M35A2]

Second dibs on the tranny!

 

[Bandit02]

I found a solution for running a intercooler.

I'm replacing the whole rad for a setup Peterbilt/International does on some of their new trucks. Its a half(rad bottom)/half(CAC top) design stacked on top of each other. I measured it and it should fit fine and still provide cooling/intercooling needs for these trucks.

 

[JohnnyBM931A2]

Why go with the 5.9 when you can have its big brother, the 8.3? 8.3 has more tq than the NHC250, though as other people have pointed out to me the 250 has better low end power. In regards to weight reduction, the 8.3 is lighter than the 250, though not as light as the 5.9 that you are looking at. Plus you would be getting double the fuel mileage of your old motor.. With the amount you drive, you would save quite a lot. Based on 12,000 miles/year and 4mpg, you're buying 3,000 gallons of diesel every year. With the 8.3, you would be using more like 1500 gallons. That's more money in your pocket, or more money to spend on your business.

Just a thought..

 

[jerry v]

whatever you do ken put it on you tube , this is going to be good

 

[WillWagner]

Hmmmm, swing an engine and reinvent the wheel with mounts, drivetrain and all the other crap, or put a couple of liners in it....no brainier, do the liners!

 

[m16ty]

If you put a 5.9 and a NHC-250 side by side, you can see why this wouldn't be a upgrade. A look at the internals side by side would be even more of a eye-opener.

 

[gimpyrobb]

For what I am doing I don't care a lick about stock, or even resale value for that mater. I put about 12,000 miles yearly on the truck hauling passengers on tours, no where near rated capacity or heavy off road. I am under the opinion that I could do it, save a bunch of weight, pick up a mess of MPG, knock off a ton of maintenance costs and have a truck that pulls/drives as good as my beasts do now. They are purpose built machines, not combat assault vehicles, well not any more. Never a haul above 5000lbs.

I have spent a lot of time quietly reading about duces repowered with them but haven't found (not that they don't exist) a 5 ton. Seems like such a simple solution, what am I missing?

Ken

With that line of logic, just put a 22re in the truck!




Just kidding, I'd have Glen at the salvage yard in Salina Ks send you an 8.3. Good guy, great prices.

 

[Jason O]

Consider the 8.3 from the A2. That engine seems "just right" for these trucks. All of the little things - engine driven accessories, brackets, cooling, exhaust, etc already exisist with no need for being creative.

Great job on your videos.

 

[acme66]

You guys are funny.

I wasn't aware the 8.3 got double the the MPG. Mine in the mountains stabilized out at exactly 4.6 MPG. The truck that dropped the liner did 5 MPG. I spend many thousands in fuel each season. Well to be honest a truck a season too but here is hoping that trend stops. As far running the 5.9 there are 5.9 powered dump trucks and buses running all over the place here in Montana. Each and every one of them underpowered and anemic but chugging along in the 28-36,000gvw range their whole lives. I have driven them, they move and they move with a load about the same as my 250's move in the same terrain.

I leave the yard and it is 7 miles to the foot of the mountain where we launch tours. 7 miles of a very gradual climb the whole distance. In my 84 923 it could hit 50mph about 4 miles into that climb, in my 83 M925 some days I never get there. That is the benchmark and it is a low one. Once I get in the hills it is all burbling slow speed tour stuff, neither motor would be working at all. It is what I meant when I said purpose built machine. I figure I will have $2200-$2500 in the 250 by the time I get the liners and pistons in it or I can grab this lower mile 5.9 and have about $1500 left over to massage it. You are right when you point out that the 5.9's in those dump trucks are flogged hard and only get 6-8 mpg but then our operation is more Old Grey Mare and less Secretariat. You guys who want to pull out and merge with traffic while climbing a pass, god bless but that isn't what we do.

I just need to figure out the output RPMs of the transmission shaft and get something close. I think it is geared to high. I know they had 5.9 airport tugs with axle rations of 5-6 but I don't have one of those. Our bus company recommended dropping the turbo CAT engine out of a early 1990's bus in there. Don't have one of those either. So much room under the hood with the 855 out of the way and a divorced t-case it should be a much more open swap than most other things. If I rebuilt, replace or repower I will updat when the decision is made.

Here is video of the 84 923 along the tour road so you can see exactly what we are doing.

https://www.youtube.com/watch?v=b3N_TcTF3O0&list=PLSw6mhcLSL-MQ8nkmYpUSF1vaMhU2rTV4&index=45

 

[swbradley1]

Who wins when someone is coming the other way?

 

[gringeltaube]

Beautiful scenery!

 

[jerry v]

get it all on video ken looking foward to watching you complete this adventureopcorn:

 

[jerry v]

Who wins when someone is coming the other way?

the brave one

 

[quickfarms]

One thing to consider is that the transfer case and two extra axles amounts to a lot of parasitic drain on the horsepower and MPG.

I have driven several trucks that had the same engine and transmission in them. The difference between the trucks is one was a two axle rear wheel drive dump and the other was a three axle all wheel drive dump. The two axle was a hot rod compared to the three axle.

My suggestion would be to rebuild the 250 or find a A2 with a good engine and other issues so you can just swap the engine without having to fabricate everything to make it work. The 5.9 May sound like a deal but the extra work is going to eat up a lot of time and money.

I remember when my mack was using a lot of oil the mechanics did the liners in a weekend and it ran like new engine Monday morning.