Swap Cummins M11 for 3116? Military FMTV M1088 tractor

[Brit]

Has anyone swapped an M11 for a 3116? I have had this on my mind for a while. Open to any thoughts. Yes, I know it is a pita. I can weld, have a cnc plasma handy and can fabricate things. I know the M11 is about 10 inches taller. Plasma cutter to the rescue ! Brit

 

[DMiller]

Everything is BIGGER, you will be modifying for awhile to shoe horn that in. 3" longer not including fan, 6" wider, 11" taller overall.

Specs: M11 L 1290mm w 973mm h 1142mm 51" x 38" x 45"
3116 L 1172 w 804 h 854 48" x 32" x 34"

6BT is closer 45" x 25" x 37"

 

[Birken Vogt]

Cummins 8.3 would have been the direct Cummins equivalent for that engine and it is a whole lot better engine. But I am sure still a lot of things to switch over.

 

[John C.]

I never thought much of either of those engines but the Cat was thought less of by a whole lot more people around here than the Cummins. Are you wanting to change because you have the Cat engine?

 

[DMiller]

I would either stick with the 3116 until explodes or go 6BT as is more reliable as I have seen that of the 8.3 and considerably less mods for the 8.3 or the M11. Will also lose considerable ground speed on the M11 by swapping from 2500rpm 3116 to 2000-2100rpm 8.3 is same as 3116.

 

[rondig]

Cummins 8.3 way better engine then 3116 or 3176 imho

 

[Birken Vogt]

Will also lose considerable ground speed on the M11 by swapping from 2500rpm 3116 to 2000-2100rpm 8.3 is same as 3116.

In my experience the 8.3 is not good for much over 2100 RPM either so you may have the same problem with an 8.3 if the truck is geared short for the 3116.

 

[Birken Vogt]

Also I wrote above that the 8.3 is the direct replacement but was thinking of a 3126/C7 not a 3116. I will also agree somewhat now that a 5.9 Cummins would be a good replacement for a 3116 and probably a whole lot more available. As for mods I generally do not care about that, I say if the factory configuration does not provide what you need then you need to buy one that has the right factory configuration. With exceptions of course.

 

[rondig]

8.3 torque is nice...but what dont you like about original engine....they are easy to find

 

[repowerguy]

How about a DT 466? Super cheap and parts are easy to find.

 

[Tenwheeler]

8.3 torque is nice...but what dont you like about original engine....they are easy to find

Running the rack and the injector cups.

 

[Truck Shop]

How about a DT 466? Super cheap and parts are easy to find.

Agreed

 

[Birken Vogt]

I just looked at what a FMTV M1088 is, it looks like a fairly compact cabover, I should think the physically smaller 5.9 Cummins would be just about the only choice now. Also has the advantage of high RPM and if this is like any military vehicles I have seen it is at redline somewhere around 50-55 mph.

 

[RZucker]

I just looked at what a FMTV M1088 is, it looks like a fairly compact cabover, I should think the physically smaller 5.9 Cummins would be just about the only choice now. Also has the advantage of high RPM and if this is like any military vehicles I have seen it is at redline somewhere around 50-55 mph.

58 MPH with a 2600 rpm engine. Depending on the OP's intended use, losing a few rpm for the 8.3 Cummins would be my choice.
In the 90's I converted a bunch of M123 trucks to 855 Cummins engines VS the POS 765 V-8 they were built with. they lost 900 Rpm but the trucks still worked fine in the field. And being hauled from job to job, top speed wasn't a concern.

 

[Brit]

I never thought much of either of those engines but the Cat was thought less of by a whole lot more people around here than the Cummins. Are you wanting to change because you have the Cat engine?

Parts and tools too expensive. Not sleeved.

 

[Brit]

How about a DT 466? Super cheap and parts are easy to find.

Can you get 400+ hp out of them and still be reliable?

 

[Birken Vogt]

You want 400 hp in the little cabover?

To get a real 400 reliable truck HP you need a 14 liter engine.

 

[RZucker]

You want 400 hp in the little cabover?

To get a real 400 reliable truck HP you need a 14 liter engine.

I have seen a few 430HP M-11's and Cat C-12's.
Just sayin.
Strangest one I saw was a Peterbilt 379 extended hood with a huge sleeper... It had a 430HP C12, when you tilted the hood you had to search for the engine.

 

[Nige]

Can you get 400+ hp out of them and still be reliable?

May be a wacky question but when the original 3126 motor is rated at 290BHP IIRC, in what circumstances would you want 400+ without risking tearing the drive train apart in short order...? Just curious.

 

[Brit]

May be a wacky question but when the original 3126 motor is rated at 290BHP IIRC, in what circumstances would you want 400+ without risking tearing the drive train apart in short order...? Just curious.

Well, I am considering everything at this point. This is why a put the idea out there. Maybe I am being unrealistic. I have the 3.07 high speed gears in the 5 ton chassis. Thought the additional HP would be helpful. They already have 330 hp in the military 3126 and I think the C7.