IDI's in Medium Duty Apps

[ameristar1]

I like where all of this is going. Hope we can see some good numbers off this engine when you two all done with it.

Hey Chris,

This has been a group effort by all those that believe in expanding the envelope, and I hope that it gets IDIs out of the backmarker status it's been in. Only problem is that when the problems get solved and they see how good this engine can run, prices for parts and services goes up.

Just being able to bounce ideas and get feedback has really helped the process along, and this site has some of the smartest folks around.

My personal goal is to make this engine as competitive as possible in the 300-500hp range, and make it affordable. Most folks don't drive anything past that hp point ( I mean, how many 600-1000hp trucks are running around in comparison to the rest of the truck population? )

Besides, having the torque with a broad, flat powerband is what people want.

 

[red66chev]

6.9 in MD

hello new to the site . followed this thread for a bit. and still have a few questions . I repowered my 1952 gmc 2 1/2 ton 6x6 (army truck) with a 6.9 and an auto with overdrive and tranfercase front drive not used.bought the whole truck and swaped the drive train. it had a 302 gas l6 and 4sd direct 4th auto. with the gas engine don't plan on doing more than 35 loaded. I haven't driven it with the diesel yet . so I'm wondering if I chose the wrong trans. its 12,300 empty. 24,500 gvw. 6.17 gears. I was thinking of using my t-19 and a gv or brownie box. its non turbo and stock pump. It gets used off and on road and I'd like to cruise at 55-60. it needs a deep first gear, as the stock divorced transfer case is single speed.

 

[ameristar1]

For something that big you need a real transmission, like something out of a MD. If you want to stay with the auto, go find an Allison AT545 out of a school bus, and get a dealer to spec the right convertor for it based on what you want to do. The busses are geared pretty low with the 6.9/7.3s and the torque convertor multiplies the torque quite a bit so you don't need a lot of power relative to the weight.

 

[1320Cummins]

What Ameristar said.
Its too bad you already have the motor because you can pick up a complete healthy school bus with the 7.3 and AT545 Ally for less than $2000.
But the 545s are almost a dime a dozen. Expect to pay about $500 for a used ready to go AT545.
Whats the diameter of your tires?

 

[red66chev]

tires are 11.00 20
i'm not at all dead set on auto it was just left over from the truck
I bought the truck for 300 for the axles and radiator for my 83 diesel xlt.
so the drive train is counted as free for the duce. I have 0 dollars in the duce other than the 800 I paid for it. If I could find a dt 466 and a spicer 6 or 7 speed. I would be tickled pink tight fit but well worth it.

 

[ameristar1]

Hey, if they can fit a Lycoming, Continental multifuel motor and 855 Cummins in those things, a little DT will be easy. You can trip over DT motors for a $1000.00 bucks these days and a Spicer prolly 'round the same money used.

With just pump mods and a good turbo you can wring almost 600hp out of it and 1500 ft/lbs of torque. Good to almost 4500 rpms. And cheaper than a Cummins.

 

[red66chev]

gmc much different cab than m35 mine is a m135 , under hood space more like pick up. when they got the 855 in the 5 TONs the cab is lifted off the frame quite a bit and the is NO room to work on it.
and I'm not looking for 600 hp i'd be breaking had to find axles. I'm looking for just enough. and I would never buy an engine seperate from a trans for a repower. just doesn't make fiscal sense. I've only ben able to find 5 spds thus far. google m135 or m211 and you'll see no to mention radiator room.
heres an m135

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heres a m35 that your thinking of btw a 855 never came ina 2 1/2 its just same cab

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[1320Cummins]

I believe ameristar is saying that people repower them with the motors he listed.
Dont forget about the DT360 if you are set on IH and of course the 5.9 Cummins. I have been looking a a 7spd OD for a while now and am having trouble finding it for a decent price.
I know of a city bus in Florida that sould for $700 a short while ago that had the 8.3 Cummins and Allison auto with 300,000 and still running and driving!! They also sold a running and driving bus with the 3208 Cat and 200,000mi for $300!!! If it would have been closer I would have bought it for the Alcoa 22.5s and tires.

 

[ameristar1]

OK, thanks for the correction. I thought they were the same. I'm not up on the military stuff.

In that case, how about a Cummins 4bt out of a breadvan? They can be made to make really good power and in a smaller package. Kinda vibey at idle, but with the gears that you have in the axles and a 5-7 speed transmission, it'll be more than enough for what you want to do, and it frees up space under the hood. Would 180-200hp and 400-440 ft/lbs of torque be enough?