turbo on a NHC 250 Cummins?

I see many people would like to turbocharge an NHC-250 and I had that interest at one point as well. I may still do it someday but only because I like the sound of a turbo spooling up. Simp has hauled many heavy loads many miles on a non-turbo NHC-250 with the fuel turned up on the throttle shaft, button change in the injection pump, dual fuel line modification and a custom air filter set-up. I have only turned up the adjustment on the throttle shaft, installed the dual fuel line set-up and modified the factory air filter housing to use more of the stock style air filter. My truck out accelerates my friends turned up Deuce on 11's and charges hills stronger. I have 14's and honestly have to be easy on the throttle on flat ground as it will be at 2,200 rpm in 5th without trying. I can only imagine the power a button change would produce but I'm happy with what I have.

To wake the NHC250 up you just really need more gears. Compared to a normal 5 spd truck vs the Allison vs the Kitty Cat. Even a nice 9 spd or 13spd would give it lots of power. The allison just drags its power level down so much. Its sad actually.

Ive got the aftercooler off a NTC400 someone could just have to run on their NHC250 with a turbo. . Or just run an intercooler and use the stock intake. I used the NHC250 intake on my NTC400.

For those considering installing a big-cam 855 in their M809-series instead of turbo-ing a 250: Before purchasing an engine, pay very close attention to varying features on an 855. Take lots of pics and measurements. There's more to watch out for other than what kind of front mount or bell housing it has. Many years ago I bought a "wrecked" M818 for parts which had a newer big-cam 855 stuffed in ahead of the stock military tranny etc.

The oil filter housing interfered with the truck frame rail (see pic) because of the offset these trucks have. So some dumbunny at the municipality decided to cut the upper web of the frame to make it fit. To add insult to the boo-boo they failed to gusset the weakened rail. In time they wound up with a ripped and bent frame. Which was unfortunate, it was a clean truck otherwise.

Here is a pic of an M809-series hood modified for a stock cummins turbo crossover pipe , and of course you can see the panel cutout for the relocated air cleaner pipe much like the M39-series. It was apparently made high enough to add jake heads in the future. I still have this hood and side panel etc. Truck was parted out.



and below is a pic of a welded crossover to facilitate not modifying a hood. The following pic I do not own, it was discovered years ago in the pubic domain and it looked like something I might consider making someday

73m819 said:

ive been told by cummins wrench turners, that to make a cummins 250 into a cummins 290 (addind turbo), you have to change the cam to the big cam, we have the little, do a major injector pump retune, change the basic timming, and a few other things to make this work. plus add cooling. i was going to do this on my m819, as a side note, found out that a jake set up wont clear the hood at the front of the engine eather, so both projects got cut off at the pass, im still going to install a exhaust brake and i guess a 10 speed od to make better use of the power that i have, just my 2 cents worth

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Canada fitted the Jakes and added a small kick up to the hood. I love the safety that the Jake's add to my M813!

Canadian Gunner said:

Canada fitted the Jakes and added a small kick up to the hood. I love the safety that the Jake's add to my M813!

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Are they the model 25B?

msgjd said:

Here is a pic of an M809-series hood modified for a stock cummins turbo crossover pipe , and of course you can see the panel cutout for the relocated air cleaner pipe much like the M39-series. It was apparently made high enough to add jake heads in the future. I still have this hood and side panel etc. Truck was parted out.

View attachment 778964

and below is a pic of a welded crossover to facilitate not modifying a hood. The following pic I do not own, it was discovered years ago in the pubic domain and it looked like something I might consider making someday

View attachment 778965

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A muffler shop can make all those bends with just one weld at the last 90+ degree bend at the intake.