Horse power for different engines without hard upgrades.

[ramdough]

I have read multiple posts on different horse power ratings for the 3116, 3126, and c7.

I realize that these motors are on many platforms that are not the standard FMTV platforms that I might find at auction. Also some of these other motors may have upgrades that are hard upgrades (not ecu flash.... like better pistons, bigger injectors, or bigger turbo).

So my question is:
If I were to get a regular 1083+ truck, what is the safe long-term tune up hp for each motor without swapping major hard components?

Thanks!


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[Suprman]

290hp is the top rating for the 3116. You can have an Indy shop tune for more but at the risk of shorter engine life.

 

[DiverDarrell]

1083 will have 290 hp, and the A1 330 with the 3126 engine. There is the rack travel screw that will get you more HP, but the two engine types are known to build heat fast "EGT". And at those ratings they are near the peak of designed output.

 

[ramdough]

So basically, you want to leave the engines stock?

How about the c7?


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[Suprman]

C7 can be bumped via computer. The 3116 is all mechanical.

 

[Reworked LMTV]

I realize that you do not want to do a hardware upgrade, but I think understanding the challenges is beneficial. I have been looking at upgrading at some point. You really need to go with a wet sleeve diesel for significant increases in power. Any increases in power shorten engine life. Wet sleeves have MUCH better cooling because the coolant reaches closer to the hot stress zones. if you want more power and longevity, look at a C9. These can handle more heat and are easier to rebuild. Did I mention 425 hp or so and GOBS of torque ? ") This is the max the tranny can handle. Impractical? Of course! Practical is so boring.

 

[Suprman]

Try driving an older deuce or even a m939 truck unless it's an A1 with the fuel turned up the Lmtv will run circles around all the older mil trucks. Unless you are pulling a really heavy load the Lmtv is geared low 290hp is a lot of power. Around town I keep up with traffic in my 230hp 1994 m1078.

 

[ramdough]

C7 can be bumped via computer. The 3116 is all mechanical.

I know this is highly subjective, but is the the C7 already at its highest durable HP? You guys have already said to leave the 3116 and 3126 alone.

Thanks


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[Suprman]

3126 in 6x6 is 330hp same as C7. I believe the C7 has room to increase power I dont have any experience with it though.

 

[Reworked LMTV]

Try driving an older deuce or even a m939 truck unless it's an A1 with the fuel turned up the Lmtv will run circles around all the older mil trucks. Unless you are pulling a really heavy load the Lmtv is geared low 290hp is a lot of power. Around town I keep up with traffic in my 230hp 1994 m1078.

Agree. I recently got my m1088 going and it pulls hard and fast with the stock gearing. Going with more hp and torque will likely cause issues in other areas.

 

[Reworked LMTV]

Has anyone done water injection on these trucks with success? I would like to keep that EGT down. Larger aftercooler maybe?

 

[Reworked LMTV]

I know this is highly subjective, but is the the C7 already at its highest durable HP? You guys have already said to leave the 3116 and 3126 alone.

Thanks


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It looks like the primary difference between the 3116 and the 3126 is the fuel delivery. The blocks are pretty much the same. Thus, the ability to transfer heat is similar and so is the longevity, from what I read.

 

[ramdough]

Agree. I recently got my m1088 going and it pulls hard and fast with the stock gearing. Going with more hp and torque will likely cause issues in other areas.

I assume you were not pulling a trailer?

My HP curiosity stems from a conversation I had with Wehring about the higher speed gears and HP. He recommended higher horsepower if you are carrying a load and using higher speed gears.

I have done the sports car with way too much tuning thing before and understand the bottomless pit tune ups can lead to. I don't want to do that with an MTV. That is why I was asking about what options for a mild tune up there are.


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[Suprman]

I would start by changing both fuel filters and adjust the throttle cable. Sometimes the gas pedal is bent, you can bend it back and reinforce it with a metal strip or it will just bend again. Look in your fuel tank with a flashlight if it has old brown fuel or lots of sludge flush it out. Maximize what you have first. Your local cat dealer can make minor adjustments on the engine to make sure you are at the rated 290hp and you might get them to tweak it a tad while they are in there. I can tell you a truck with a new/reman engine has more pep than a 90's one. Alot of it may just be adjustment though. Way out of my league messing with a cat engine though.

 

[Reworked LMTV]

Just an FYI, these engine often self- destruct by dropping valves.

 

[snowtrac nome]

these engines are known for a lot of things dropping valves aren't one of them. Seat failures and injector cup issues in a few sn ranges for shure . most failures how ever can be traced back to an overheat condition or air in the fuel system causing injection system failures. one thing these engines are known for is being thirsty, so if you want crappy fuel mileage to get worse with minimal seat of the pants feel, start twisting on fuel screws. I have the ability to raise the hp I'm opting not to do it after I have seen the long term effects to my dodge ctd.

 

[Reworked LMTV]

these engines are known for a lot of things dropping valves aren't one of them. Seat failures and injector cup issues in a few sn ranges for shure . most failures how ever can be traced back to an overheat condition or air in the fuel system causing injection system failures. one thing these engines are known for is being thirsty, so if you want crappy fuel mileage to get worse with minimal seat of the pants feel, start twisting on fuel screws. I have the ability to raise the hp I'm opting not to do it after I have seen the long term effects to my dodge ctd.

Just Google the complaints. You will see what I'm talking about.

 

[snowtrac nome]

complaints are one thing, I have also seen where the blocks are junk because they were cast in france. there was a limited run of weak blocks that had this problem, but a google search would have you think all the motors had this problem. the sn series for the lmtv' were built here in America with cat personnel, not scabs from the strike. they should be plenty robust as long as you don't overheat them or let your fuel get aerated in the fuel rail. I maintain a fleet of trucks with the big brother c-7s in them one dating back to 95 the only prblems have been front cover oil leaks turbo seals failing and a heui pump the other thing to remember is the lmtv has the high hp 3116 the duce has the low hp 3116 turn a low hp motor up over 200 hp and it isn't going to last long.

 

[ramdough]

complaints are one thing, I have also seen where the blocks are junk because they were cast in france. there was a limited run of weak blocks that had this problem, but a google search would have you think all the motors had this problem. the sn series for the lmtv' were built here in America with cat personnel, not scabs from the strike. they should be plenty robust as long as you don't overheat them or let your fuel get aerated in the fuel rail. I maintain a fleet of trucks with the big brother c-7s in them one dating back to 95 the only prblems have been front cover oil leaks turbo seals failing and a heui pump the other thing to remember is the lmtv has the high hp 3116 the duce has the low hp 3116 turn a low hp motor up over 200 hp and it isn't going to last long.

What do you like better, the 3126 or c7? Why?


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[scottmandu]

The 3116 is for all intents and purposes an entirely different engine compared to the C7 and 3126.

The 3116 had HP ranges from 180-375hp
The 3126 had hp ranges from 180-425hp
The C7 had similar power ranges up to 475hp.

EGT's climb fast in the 3116 because the turbo is so restrictive.