cummins nhc 250

[712edf]

Since my search for a W500 within the same hemisphere is somewhat fruitless I've been eyeballing military 5 & 10 ton 6x6's and "bobbers". Alot of these old rigs have the cummins nhc250 inline six diesel in them. Is anybody here familiar with them (the motor)? From what I can figure out they are 855 cubic inches, 250 hp, non-turbo, redline at about 2300 rpm, get 8-10 mpg, and top out in these trucks at 60 mph. I know they have nothing in common with the 4bt/6bt engines ya'll discuss here. How much torque does this 855 produce? Can they be modified much or is that even a consideration since these giant trucks can use their weight to drag whatever irritates them outta sight? Thanks for any input on these old engines.

[MoparNorm]

I lost interest at about the "8-10 mpg" part....= )
I bet a W500 will show up sooner rather than later...= )

[712edf]

Hi Norm! Yeah that 8-10mpg is what various sellers' of these trucks claim, which considering the weight ain't bad, but it is what it is. I've just found some specs on the nhc 250 and the torque numbers are in the 680-800 range depending on the model. The engine was produced from around late 50's to at least the 80's. It seems the nonturbo thing is why the power per displacement is so low. Understand I wasn't considering swapping in one of these engines, just looking at some 6x6's that came with 'em. Dodge even used the nhc 250 in some of its medium & heavy duty series rigs of the 60's/70's.....I hope your right about a W500 showing up someday! Thank you for your time.

[MoparNorm]

...and the torque numbers are in the 680-800 range depending on the model...

Not too many stock drivetrains that could live long behind those numbers....= )

[Charles Talbert]

I'm very familiar with 250's

8=10 MPG is a sellers line forget that unless it's in a VW or a motor scotter. They are one of the all time greatest Cummins engines, the later 270 & 290 is nearly the same only in a turboed version. The only M series military trucks that used them were the 800 series 5-tons. They will be a huge weight issue in any light vehicle, weigh in at around 2,000# maybe a little on the + side of that figure. They have the old stand by "PT" fuel system, injectors are mechanically operated by a rocker arm system. The injectors are of the famous Cummins "top stop" variety. Has 4 valves per cylinder, 2 intake, 2 exhaust, operated by single rocker arms via a bridge type system. Tune up procedure is very maticulous, has to be done precisely in order to get top performance, just 1 tiny air bubble in the fuel line will stop the show in its tracks. They are a great engine if you understand how they operate & making adjustments to bring out the best. Their long stroke & large 5.125" bore makes them the king of hard lugging engines in a vast RPM range. The old Cat engines are the only thing that even compared with their superior lugging ability. These were work horses of the day, not intended to be a high RPM hot rod at all. You can see us running the overhead on one in the photo/client pages on our website, look for Todd Brock, Brock excavating. Click on the link under the picture to view service we performed on his 800 series 5-ton dump truck.

[712edf]

Thanks Charles! Thats what I've been looking at, 5 ton M818 series and the like. I wish I was more competant in the area of diesels, or anything else made after 1978 for that matter. I just like the looks a of a 5 tonner, 10 tonner is even better. I just don't see me running to Autozone or Napa for a quick $50 part. I want something different and why spend 40 grand for a dually megacab when I can get 4 times the machine for 1/4 the price.

[Fred_M]

you can expect 5 mpg and they weigh real close to 3000lbs
will run forever with a little care and cheap to rebuild.

also many of them were converted to propane and used for pump engines