Mo' Power for an M923A2

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Steelreaper80

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So.....theoretically would an Allison HT754CR bolt up to a Cummins ISL if one had the inclination to pull the 6CTA and MT654CR? Would they fit in these trucks? Just wondering.......
 

74M35A2

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Medium and heavy duty engine to trans connectivity typically follows SAE standard orientation. You can nearly bolt anything to anything, as long as it is not proprietary. Some require unique flywheel housings, but still yes.

ISL power range is 330-450hp. Externally same dimensions as 6CTA8.3, ISL is just stroked and modernized 8.3L displacing 8.9L.
 
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Floridianson

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And there is something to be said for a mechanical injection system and manual transmission. Mate the turned up 8.3 to a manual.
 

Csm Davis

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So.....theoretically would an Allison HT754CR bolt up to a Cummins ISL if one had the inclination to pull the 6CTA and MT654CR? Would they fit in these trucks? Just wondering.......
The only thing that might give you problems is the transmission is longer but I think you can squeeze it in by just shortening the drive shaft.

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simp5782

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You should be able to get near 500 HP from the 8.3L. change injectors and turbo, and turn up the pump.
And it'll last its first oil change before its burned up being worked. Marine applications have higher HP ratings due to the work process and an unlimited capacity cooling system.


A manual transmission will help alot. The difference between the 654 and the CAT 7155 is incredible as to how much more power you can feel when climbing hills or acceleration from the non turbo NHC.

Steel - turn the screw. Turn the aneroid gear up as well. Upgrade your air filter to the setup from those military guys or cut the extra piece out of the intake to start. Then play with the turbo upgrade for the H1E and then go to injectors. The allsion is the power killer for these engines though.
 

Steelreaper80

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I have already done the TMG air filter and cage, plus the RAM air system. I did notice a little bit of MPG increase but not a lot. I plan on this year having the fuel pump turned up plus the boost and EGT gauges installed from TMG. I am still trying to figure out what the part # is for the correct larger injectors for this engine.

So here are the specs for both the MT-654CR and the HT-754CR

MT-654CR
Max net HP-300
Max torque-950 ft lbs
rated to 80,000 lbs
1st: 4:1-1
2nd: 2:21-1
3rd: 1.66-1
4th: 1.27-1
5th: 1.0-1
Rev 10.76-1
Length- 36.2"
Width 19.3"
Height 22.4"
Weight 709 lbs

HT-754CR
335-500 Net HP
Torque- 1075-1575 Ft lbs

1st: 3.39-1
2nd: 2.00-1
3rd: 1:58-1
4th: 1.25-1
5th: 1.0-1
Length 43.4"
Width 21.7"
Height 26.6"
1075 lbs

Simp,

How hard was the 7155 to install and do you lose 6 wheel drive?
 

74M35A2

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This is a second thread to the already going 8.3L hop up thread.

Anyway, our generation (1990) of 8.3's are somewhat limited due to a weaker block deck. It can crack easily, and was later fixed about 1992 or so. The injector choices are easier to come by now, because a lot of shops can make the nozzles themselves via EDM and other processes. You just spec hole size, # of holes, and spray angle. The 5.9L/8.3L was commonly hopped earlier by using higher flow "marine" injectors, and it will make more power, but they run hot EGT's and produce excessive black smoke due to the spray angle not being optimal vs injection spray timing and piston top bowl design of the non-marine config engine.

Anybody who has simply turned up both pump screws seems to have impressive results, enough to make them say it is a LOT better, and not lethargic off the light anymore. I would guess do that, put a 5.9L GSK (Governor Spring Kit) in it, and set injection timing to 16 degrees, and you'll be good to go. Power and mileage efficiency should both go up.

Simp is right in saying they can squeeze that much power reliably from the marine version due to the infinite cold water availability for both the radiator and charge air cooler.

ISL power range is 330-450hp, stock. Even the lowest spec one is nearly a 50% power increase over the 6CTA8.3 240hp rating. Early ones were non-emission. These engines can be had relatively cheap, slightly more than the cost of a used Bosch "P"-7100 pump. I'd avoid the earlier CAPS type hybrid injection pump ones, they seem failure prone. Even though they are electronic, they are self contained, and only need a throttle pedal sensor to run stand-alone. Can even use one from a diesel Dodge Ram, or a cable driven one made for marine adaptations to keep the stock pedal. Re-use the stock 8.3L flywheel housing if you are keeping the Allison MT654CR, as it is unique to it by being 1" deeper. The 6CTA8.3 oil pan and pickup will need to be reused onto any ISC/L engine for front prop shaft and axle clearance, but they do fit.
 
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tobyS

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And there is something to be said for a mechanical injection system and manual transmission. Mate the turned up 8.3 to a manual.
Would that be like a Spicer from an 809 series and a T1138 transfer case? That would be a nice combo for a 4x4 818.

Is there a TC that is not prone to self destruction while backing in low?
 

74M35A2

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The flywheel housing on the military 6CTA8.3 in the M939a2's measures out to be about one inch longer than a conventional flywheel housing for a manual trans with a clutch. Just FYI, it may be specific to the Allison MT654CR due to the necessary clearance for the torque converter. The trans input shaft into crank pilot bearing, clutch friction disk position on the input splines, and throw-out mechanism would all be off by an inch.

Yes they are SAE #2, and you can get an SAE #2 clutch housing for nearly any manual transmission. I have done it with a 13 speed Eaton/Fuller Road Ranger, but have not installed it yet.
 
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