NHC 250 Turbo Conversion in M923

[airborneinfantrygrunt75]

I have an M923 also and want more power out of it also. I am going to get to this part at some point and be all in! Right now I am doing simple stuff like simplifying the batteries to 2!LOL!

 

[98G]

I have an M923 also and want more power out of it also. I am going to get to this part at some point and be all in! Right now I am doing simple stuff like simplifying the batteries to 2!LOL!

I recommend the dual fuel mod.

I don't recommend a turbo. The NH250 lacks the oils squirters needed for it.

That said, I've got an M818 with turbo, and I'll be driving it up I-35 sometime in the next few weeks. You're welcome to look and see how the turbo was added..

 

[74M35A2]

Swap out the old dinosaur engine with something more modern. It can be done cheaper than you think. I am doing it to my M925a2. I just bought a 24 valve common rail Cummins ISL motorhome engine for a song, much less than what people here spend trying to hop theirs up and then battle smoke and high EGT's. I'll have 400hp of smoke-free, low EGT, reliable power.

An old truck with a modern engine can be a pretty sexy piece of equipment.

 

[Jbulach]

Now where did I put all my kitten photos...

 

[grendel]

Swap out the old dinosaur engine with something more modern. It can be done cheaper than you think. I am doing it to my M925a2. I just bought a 24 valve common rail Cummins ISL motorhome engine for a song, much less than what people here spend trying to hop theirs up and then battle smoke and high EGT's. I'll have 400hp of smoke-free, low EGT, reliable power.

An old truck with a modern engine can be a pretty sexy piece of equipment.

Discoball, just because you bought the parts doesn't mean you're doing...

How long you had that trans?



I have 900 into my 400hp up grades

 

[74M35A2]

Because I am waiting for a clutch for it. HA!

Secured trans when it became available. Plan was always to install it once the MT654CR goes south. New engine may shorten it's time remaining.

Engine will go in even though 6CTA8.3 is alive and well, but I gave the seller a lot of time to pull it. So, be patient.

You have no idea how much power your engine will make. MW pump is supposedly only good for 300hp max with its 10mm plungers, fuel supply is limited (cc delivery per stroke). A pump shop could flow it and tell you the max HP it would be able to make. Mine will be SAE certified HP, smoke free, with low, continuously sustainable EGT's, for about double your stated cost. A good deal I believe. Especially since I can sell my good running engine for the same amount, net upgrade cost should be near $0 (you spent too much, ha!). If you like your 6CTA8.3, you can keep your 6CTA8.3. But, you should put your big girl pants on and step up to a 12mm P-7100 pump. Make it string-less, know what I'm sayin'?

 

[grendel]

You already said you're sending me the 6CTA 12MM P7100. Get on with it.

 

[71DeuceAK]

Curious, on a related note, 74M35A2, would your soon to be new setup pass the California emissions laws? As someone who is moving back there eventually, hopefully an M939 in tow, I'd like to repower to get around the bans.

 

[74M35A2]

It will pass the laws of the emission generation it was manufactured. In my case, it will be a 2005 engine, in a 1990 truck. But, I think emission laws are based off the vehicle mfg date, and not the engine? Interesting case though. If for some reason your area requires a sniffer test, then this would be a good way to consider it. I am paying $2000 for the engine, and I can probably get $2500 for my good running stock 8.3L. You can get an even cleaner diesel by going even newer, but at that price level it would be lower hp, but still probably every bit of 330hp or so.

 

[snowtrac nome]

the commifornia emissions laws are stupid, and not related to year of manufacture but rather latest technology which is why you can get older engines so cheap from there, and for every truck leaving the state 2 have to have the engine demilled. my compant bought a yard tractor there several years ago and 2 had to be scrapped for ours to leave.

 

[74M35A2]

Spot on. Found it. Looks like maybe try a historical way or apply as a business with less than 3 trucks, or keep it registered out of state, or...?

https://www.arb.ca.gov/msprog/onrdiesel/onrdiesel.htm


So, about that 250 turbo power up....

 

[71DeuceAK]

Interesting! Mine wouldn't be "commercial" per se, just frankly a daily driver and also off road/mud toy, but CA thinks of just about everything triple-axle as commercial, even a Deuce!

 

[simp5782]

I have an M923 also and want more power out of it also. I am going to get to this part at some point and be all in! Right now I am doing simple stuff like simplifying the batteries to 2!LOL!

Intake system, dual fuel line mod, modified pump. Few other tricks are out there to open her up

Sent from my SM-G935P using Tapatalk

 

[wrenchturner6238]

I have added a turbo to my 250, pilled the pump, added shims to the high speed spring and really like the performance so far. I have about 210 psi rail pressure, 13 psi boost, I have not been loaded up yet but I get about 750 to 775 temp on pyro max boost and rail psi (post turbo). No smoke going down the road, just a little puff at the end of RPM when you snap the throttle.

 

[74M35A2]

Nice tune. EGT actually seems a pinch cool?

 

[wcuhillbilly]

Turbo and a properly tuned pump will cool the 250 down some... mine was running hotter naturally aspirated, now I see 700-900 instead of the over 1000*F temps pre turbo....

Simp, you still got a line on a good pump rebuilder ???,,, mine is taching out at 1800 and I suspect its got low pressure as the shims/button and screw have all been messed with.......

 

[74M35A2]

Does the stock Cummins 250 PT pump has a provision to add fuel under boost? I would guess not, and you are just pouring more fuel in?

 

[wrenchturner6238]

Well no the 250 does not have an AFC but through the full range of RPM down the road my truck does not smoke.

 

[74M35A2]

Understood. Looks like you could up the fuel even more then if you wanted?

 

[Farmallmilitary]

I just picked up a big cam 400 that is complete. (Which I got for free) Only downside is I was told it has a rod knock. I was planning on using it as a donor for the nhc250 in my m925a1 for a turbo swap and probably add jakes to it as well. What I was wondering. Should i swap the jakes, injectors, and injection pump over as well? Or should i just swap the turbo and cooler? Another option I was thinking of doing was swapping my internals into the bigcam (as long as the block is still good and didn't spin a main bearing).... that way I would have cooling nozzles. Anyways, I have quite a few options and would love to get some input on what I should do.