M923A2 Engine Swap

[jdknech]

JD, what's needed to get that much more power out of the 8.3?

Also, at what point is the transfer case going to grenade? We already know it can't handle reverse in low range.

those are 2 questions I really cant answer.. as i have not personally messed with a 8.3.. but there are a few people on here that have.. and at the haspin rally a got to ride in one that had been turned up to 350.. it was very "peppy" to say the least.. plus he was claiming 14mpg..
as far as the transfer case, low-R has a TON of TQ on it.. I'm not sure the exact numbers, but it is WAAAAAY up there.. (reverse is a very deep reduction) to get enough HP to start crapping out T-case's (in forward gears) your going to have to be dogging to crap out of it..

just remember guys.. these arent race cars! the power is for pulling, not speed..

 

[Jim Timber]

I'm all about pulling, and not about speed. I'm just also a gearhead to the core and can't leave anything stock.

14mpg is in line with my Tahoe. I'm gonna have to look into that. lol

 

[ejpolson]

JD...
What would I need to do to get 350HP out of the 6CTA8.3? Will I have any overheating issues? I'd rather stick with what's in it, and modify it from there. I believe the Allison 4500 RDS is the best fit for what I want to do... get 350HP in the truck. All of you have been very informative, and now it's time to get going. If I can do an "in-frame" kit in the 6CTA8.3 and get the 350HP I want, then that would be my best answer. I've looked at a lot of other sites' postings, and they just dance around the information I want. So... here goes:
What do I need to do to get the 350HP in-frame?
Will the transfer case hold up, or which one will I need to remain rock solid?
Is there a better alternative than the Allison 4500 RDS?
Any specifics and/or links to specifics anyone can provide would not only be VERY useful to me, but others that follow that might want to do a similar upgrade.

Again, thanks for all the info so far. I guess the specifics are what is needed now.

 

[Jeepsinker]

Have you turned up the fuel rate and the governor?

 

[Floridianson]

I would just get a 400BC. I know braging rights but 600 hp would never be used unless you are pulling over 80k plus over a mountian. You would be surprized at what a 400 can do. I have one in my M920. As for the swap 809 and 939 series need front motor mount work and it has to be right.

 

[ejpolson]

I've gotten a lot of feedback on the 400BC, BC400, BC-400, but I don't easily find them on the internet. What would be the specific model for the BC400? I'm seeing NTC400, Form 400, ISM 400, ISX 400 (which I think has too much electronics)... I'm just hoping to get a little better clarification on a model that I can find solid information on. I'm definitely going to do the BC either 350 or 400, but need a little more help in narrowing a specific Cummins model identifier. As for any mount modifications, I'm pretty sure I can get that right, as I've done a few gas engine transplants that required some exacting alterations.

 

[Floridianson]

M920 M916 M915 are the ones I have had. Maybe just get you a M916?

 

[Jeepsinker]

You can narrow it down to the NTC 400 and the form 400. Probably easiest to use the NTC.

 

[nevrenufhp]

A bigger reason to keep the 8.3 is the rpm capability it has. As most of you know about mud, having a broad rpm range can help keep you from getting buried. An ISX may have plenty of pep, but it will only rev to 2100. Get a hot rodded 8.3, and you can run to 3200. Plus, you would have the timing advanced, which gives less low rpm torque, and less broken parts in general.
Simple way to big power on an 8.3?
Marine injectors.
Swap to a P-pump with gov spring kit and #0 fuel plate.
Swap to bigger turbo(HX52 or 55).
Head studs for extra insurance.
Timing set up to around 22*.
With the right pump, it can make a tad over 500hp with the ability to spin to 3200.

 

[Jeepsinker]

A bigger reason to keep the 8.3 is the rpm capability it has. As most of you know about mud, having a broad rpm range can help keep you from getting buried. An ISX may have plenty of pep, but it will only rev to 2100. Get a hot rodded 8.3, and you can run to 3200. Plus, you would have the timing advanced, which gives less low rpm torque, and less broken parts in general.
Simple way to big power on an 8.3?
Marine injectors.
Swap to a P-pump with gov spring kit and #0 fuel plate.
Swap to bigger turbo(HX52 or 55).
Head studs for extra insurance.
Timing set up to around 22*.
With the right pump, it can make a tad over 500hp with the ability to spin to 3200.

Now that is some real actual helpful and useful information! Thank you!

 

[Jeepsinker]

Any mods needed to the lower end to run 3200 rpm?

 

[Suprman]

No the engine is made to be able to spin that high.

 

[Vintage iron]

I sold a Big Cam 400 to a SS in Conn. He put it in his M929 dump truck with a few modifications. His buddy at Kenworth looked up the info. on the Allison transmission in his truck and found that it will handle up to 500HP. I am will be putting a Cummins Big Cam 290 in my M923 in March.

 

[Stevepala]

Matt are you talking about me, my ears where ringing.

Big Cam is the way to go. Easy to install being basically the same dimensions. The jakes make it taller so you need to lift the cab and nose on the mounts about an inch to make it clear the firewall. All the plumbing is basic too, just need to remote mount the oil filter. The front mount requires cutting the cross member, determining the correct height of the crank snout and welding in some heavy steel for the motor mount to site on.

I had Pittsburgh Power rebuild the PT pump and increase the output. They estimated it's now close to 450hp. It really moves out with 1600r20 on it.

Steve

 

[Mike929]

No the engine is made to be able to spin that high.

Why does the army consider red-line around 2200-2300 with the engine if it can safely spin at such a high RPM? (honestly curious, not a hidden jab or attack of the 3200 RPM number.)

 

[tim292stro]

You ever see Blade Runner? The quote about running things hard applies there:

In order to run the engine reliably at those revs under load, you'd have to do a lot of work: balance the engine components better, increase bearing sizes and strengths, use different heat treatments on shafts to keep them from shattering/shearing, increase your fuel and air intake and exhaust sizes to accommodate the higher air flow volume.

Efficiency also comes into play, your peak torque is going to be somewhere around 1600RPM, and your peak power somewhere around 2100RPM. Going higher than than will be past the point of diminishing returns, like the 80/20 principal: 80% of the effort is going to produce 20% of the work (i.e. a LOT of waste).

 

[Flat Black]

Did you ever make a decision on this? I would certainly keep the CTA motor and build it to your needs. Absolutely no reason to swap it out, certainly not with a Big Cam Cummins. The 8.3 can EASILY make 450-500 hp and 600-700 is not a stretch at all. Call some shops like Scheid Diesel, Garmons, TST, etc. Any of the big sled pulling or drag racing shops should be able to tell you exactly what you need. The mechanical motors are bulletproof and will run on almost anything. Many of the military CTA's have the MW pump instead of the Bosch P7100, so keep that in mind.

An SAE#2 bellhousing should give you a ton of options for both manual and automatic transmissions. A company like Suncoast could probably build an Allison automatic (2000/2500 series) to handle 1450-1850 pounds of torque, but you might not want to pay the bill on that build. ($10 -15k is my guess) not sure how that compares to some of the other options mentioned.

If you dont mind rowing your own gears, get an Eaton Fuller manual and throw a good heavy duty clutch in it and you are just about set as long as you dont go stomping on the gas in first gear. Many new auto trans for the higher HP truck motors are limited to working with the engine and only allowing a certain amount of torque until the RPM and/or MPH come up to acceptable levels.

If you insist on swapping the motor, I would only consider building a mechanical DT466. You should be able to get 550-600 hp out of it very easily with a call to a shop like Hypermax Engineering or Gene's Garage. Very popular in the tractor pulling world with several in the 2500 - 3000 HP range on several hundred pounds of boost. Not sure what they are doing for transmissions to hold that kind of power, but it comes on at much higher RPM, therefore you lose the large TQ to HP gap common in larger diesel engines.

 

[Hawssie]

I think you first need to set a budget, then set how much work your willing to do or pay someone to do. Anything 15 liters or less should fit as the 855 in the first models is about at that size. If you go computer controlled getting a package with trans, wiring and complete engine with the computer would be easier. I think an N14 with a 10 speed would be a nice package being easy on all the above. There are better and more powerful choices but Red tops get to 500 Hp. You will of course need to add an inner cooler for the turbo as the 8.3 is water to air and is built into the engine itself. This all depends on what you want to do. I am thinking more like a truck driver, maybe you dont want to shift. But the Allison is a hinderance for using it as a truck. Incidentally the only thing that got me thinking of buying a 939 or 939A1 instead of all the A2s I bought instead was that it would be easier to swap in one of the newer 855 Cu inch engines such as the big cam or the N14. I have a small cam right now in a Kenworth that has the water to air cooler on it that would be the easiest of swaps for replacing the NHC250. But at stock levels its just a 350 HP. Although the torque is of greater increase over the NHC250 then the HP would indicate. But then again I would like to swap out an 8.3L also because I would like to free up that engine to swap into a smaller vehicle, If I started with the NHC250 I would be left with just a boat anchor. You could argue getting a M939A2 in the 3-4k range is about worth it just for parting out if you need the engine as its hard to find a turbo cummins for that unless it has a lot of miles. Most of the 8.3Ls I got are closer to new then not.

 

[Carlstealth]

A bigger reason to keep the 8.3 is the rpm capability it has. As most of you know about mud, having a broad rpm range can help keep you from getting buried. An ISX may have plenty of pep, but it will only rev to 2100. Get a hot rodded 8.3, and you can run to 3200. Plus, you would have the timing advanced, which gives less low rpm torque, and less broken parts in general.
Simple way to big power on an 8.3?
Marine injectors.
Swap to a P-pump with gov spring kit and #0 fuel plate.
Swap to bigger turbo(HX52 or 55).
Head studs for extra insurance.
Timing set up to around 22*.
With the right pump, it can make a tad over 500hp with the ability to spin to 3200.

I have a Question about increasing timing to 22 deg. My engine is set to 16 deg factory. 6 deg seems like a lot. I have increased 5.9's a few deg with success but too much and they start making scary noises. Can you tell me if you have done this with success ?

 

[nevrenufhp]

I have a Question about increasing timing to 22 deg. My engine is set to 16 deg factory. 6 deg seems like a lot. I have increased 5.9's a few deg with success but too much and they start making scary noises. Can you tell me if you have done this with success ?

The 22* is only if you can rev up past 3k. On a regular 8.3, I wouldnt go over 3-4* of advance, and 16 is decent. Most of what I mess with is a DT466, which is a very similar setup as these(almost identical pumps). The low end torque really suffers with timing of 20 or higher. On the flip side, the trans will like it a little better with the torque a little higher in the rpm band. For normal driving, if you play with the timing, you'll find it will probably only want 1-1.5*....sometimes not even that much. It's all in how you like it.