m923 seems a little weak

[jester3798]

hey guys, just putting out a question. My buddy was pulling about 19k with his 923 up a hill and he said it was really lacking in power. it dropped down to first gear and by the time he got to his destination all the temp gauges were way above normal and it "smelled" hot. so the question is.....how can we get a bit more power from our motors with out really sacraficing reliability? opinions and ideas welcome.

thanks
ryan

 

[moriboy]

You probably won't get many responses on this....There just arent any easy/cheap solutions to get more power out of these motors. I have the same truck so I now how under powered they feel on a hill. I still love driving it though!

 

[M813A1]

Unfortunetly you are limited to what you can do because of the automatic transmission !!

 

[Clayshootr]

I know my M 931 is the same way. I was bringing home seed and fertilizer the other day and I was down in first going up some of the larger hills.
I spoke to several shops about my lack of power and was referred to a diesel shop that has been around for a lot of years. I spoke to them and gave him the numbers off the engine. He is going to check the fuel pressures and timing. If they are OK then he wanted to pull a turbo off a 290 Cummins. I was just afraid if we get up around that 300 hp range the tranny may not hold up.

 

[wreckerman893]

The "Nifty 250" is a dog...always has been...always will be.....you can turn the fuel to it, add a turbo, put propane or NOS on it and it's still going to be a bow wow.

These were never meant to be high speed trucks...thats what the line haul trucks were for.

For what you'll spend to fix the problem you can drop in a pull out 400.

Ditto the transmission......for every action there is a reaction.....put more power thru the Allison and you may break something in the tranny.

I suspect your buddy was banging the governor and running WFO......the trick to pulling a load with these truck is to find a gear it will pull in at around 1800 RPM and let it pull.......running it wide open just sucks fuel and builds heat.

You will go slower but you are less likely to damage the engine or tranny.

Hope this helps.

 

[poorman4x4]

I recently purchased a 1987 M923A1 which i can say is in very good shape. I've been to lots of diesel shops and injection specialists, they all say the same thing. "Do not waste your money on the 250". Best shot is to get your hands on a big cam cummins 400 and complete the swap, as per the guy above me said. Im collecting as much info as i can to complete a 8V92 Detroit swap in mine, but i just cant get away from how much i like the original factory build of a military truck.

 

[wsucougarx]

What the truck lacks in power up hills, it makes up in smoke. Nothing like rollin' coal up those grades. That carbon signature definately puts a grin on my face

 

[Beerslayer]

I checked the numbers with the local Allison shop and the transmission is rated for 300 hp. If he installs the turbo off the 290, 350 hp injectors, and recalibrates the pump accordingly, he will be a lot happier. An owner operator that understands just what he has and knows how to be careful with it when pulling a hill with a heavy load will be fine with that combination. A driver that drives it like he stole it, and stands on the throttle while loaded heavy on a hill without watching the EGTs will burn up that turbo in short order.

There are already several threads here on getting more power out of the 250. They are complete with everything you need to know on this subject.

 

[quickfarms]

Interesting

 

[quickfarms]

I just realized that the OP said he was pulling 19 k lbs in a 5 ton truck on a hill.

Is this the weight of the truck or the weight of the cargo?

If this was a 19k trailer then he overloaded the pintle by about 4K if I remember correctly.

If this is the weight of the cargo then the truck is 1K short of the designed capacity.

 

[wehring]

tires...

If he is running the 49" singles he can drop to the 1100R20s and get more "power"

Justin Wehring
979 997 3112

 

[joeM62]

whats the difference in the BMY trucks with their motor and the regular M900 trucks motor power and turque?

 

[jcappeljr]

That sounds about right,I have pulled a trailer with a 10 ton excavator and also a 18 ton loader,hills really kill these trucks.they lack on power.

 

[jester3798]

we bought a scrap big cam motor and are going to "steal" some of the parts and do a little transplanting. ill let you guys know how it turns out

rc

 

[seano11]

Has anyone tried taking the old steel fan out and putting a plastic fan in ? I read somewheres that those steel ones take 60 horse to spin at full tilt where a plastic one only takes 40

 

[MidnightDuramax]

Well if it really is that much I would ditch the mechanical and go with an electric fan.

 

[jrod66]

I commented on putting electric fans on the 250 in another thread but didnt get any responses, is there a fan that will pull the needed CFM's? I would think this would be a good upgrade, and even if 60hp is a high number if you could get half of that back you would be in great shape, I plan on going electric when I get my 925

 

[spicergear]

If this was a 19k trailer then he overloaded the pintle by about 4K if I remember correctly.

.

My 931 is rated 15,000lbs pintle and 37,000lbs 5th wheel.

 

[quickfarms]

Well if it really is that much I would ditch the mechanical and go with an electric fan.

How big is the charging system?

I think the existing fan has an air clutch so it only runs when it is needed.

 

[Checkmate]

whats the difference in the BMY trucks with their motor and the regular M900 trucks motor power and turque?

No difference. All of the Base and A1 models run the NHC 250 while the A2s have the 6CTA8.3. The transmission for all models is the same from what I can tell.
NHC 250
- 250 HP
- 685 Ft-Lbs
6CTA8.3
- 240 HP
- 745 Ft-Lbs

BMY is just the company the contract went out to after AM General stopped filling orders. The government gave the the exact same specs to BMY. So, the AM Generals are the same as the BMYs except age since BMY is the second contract holder for M939-Series 5-Tons.