900a2 series compared to 800 series

[seano11]

Just my thought's on the 2. My m923a2 sucks on heat output compared to the 800 series. Not sure if its the smaller 8.3 not putting out as much heat at the 14liter or what but very noticable temp diff in the cab. I'd like to hear from guys with a1 900 series with the 250 if it puts out proper heat. Maybe the larger cab has something to do with it ?.Sound difference is very noticable the a2 is whisper quite compared to the 813. cold starting with the 8.3 is much better at -20 with no ether or warmers the 8.3 will fire right up. The 250 not so much very cold blooded.New style axles are a great bonus when dealing with snow the a2 has about a extra inch or 2 of ground clearance due to the new axle design. smoothness is much improved with the rubber mounted cab on the a2

 

[sam777]

I have the M931a2 with the 8.3 and get great heat in the cab. Although the outside temp is about 30 to35.

 

[seano11]

Might have something to do with the extreme cold then

 

[gimpyrobb]

I also know fresh air is ducted to the heater in the 900 series from the grilll. I don't remember the 800 series haveing a duct to the fresh air. Many posts about the heaters say they should be mounted in the cab for MUCH better heating, as they can re-heat the air in the cab rather than cold air outside.

 

[doghead]

Not sure if its the smaller 8.3 not putting out as much heat at the 14liter or what but very noticable temp diff in the cab.

Could you clarify that statement?

I understand the A2 has a turbo but, are you saying it also has a different sized motor? Please post details( like a side by side comparison).

 

[Nonotagain]

The A2 trucks received the Cummins 8.3 liter engine. 8.3 liters is 505 cubic inches

The plain flavored trucks and the A1's have the Cummins NHC-250, 14 liter engine. The 14 liter engine is 855 cubic inches.

My guess as to the lack of heat is that one of the fresh air doors wasn't fully closed and was mixing with air going across the heater core, reducing the as felt colder temperatures noted.

 

[doghead]

What HP is the newer engine?

 

[swbradley1]

You're testing him aren't you?

Change your avatar too, it's creeping me out with those eyes............

 

[BKubu]

6CTA is 240 HP; NHC250 is 250 HP. Torque is a wash, I believe.

 

[Rkrug]

NHC250 good heat

My M923A1 with the NHC 250 puts out great heat. Might check your heater (Green box pictured ) the fins on the mini radiator might be pluged up with gunk that would impede the transfer of heat.
Just a thought.
RK

 

[doghead]

You're testing him aren't you?

Change your avatar too, it's creeping me out with those eyes............

No, I have no experience with the A2s.

A real numbers comparison would help this thread with some facts and might educate people like me.

So far, smaller displacement and same HP, how can that be better?

What is wrong with Santa's eyes?

 

[seano11]

No, I have no experience with the A2s.

A real numbers comparison would help this thread with some facts and might educate people like me.

So far, smaller displacement and same HP, how can that be better?

What is wrong with Santa's eyes?

That little 8.3 sure seems like it puts out more power then the 250. But them again I haven't driven a 250 in a 900 series truck

 

[Sumner]

I think it would be a very easy engine to bump the hp up on. In motorhomes they are usually at 335 to 350hp in stock trim, and up to 500hp in marine applications,so I believe it would be just a matter of adjusting the pump up a bit. I was on cumminsforum doing some reading in this engine. A google search brings up tons of info on these engines. I wonder what hp the Allison transmission is capable of handling?

 

[Castle Bravo]

Having driven a M931, M931A1, and M931A2 all in nearly the same conditions along the same route for the same duration, I can say that there really isn't a terrible difference between the trucks. I'd say the larger tires are more of a change than the different motor is. The 6CTA motor seems to have more top end, but the 250 seems to have more grunt at the lower end. Either way, its not enough to matter in my opinion.

 

[doghead]

What about fuel consumption?

Seems a smaller motor might be better there?

 

[Nonotagain]

What about fuel consumption?

Seems a smaller motor might be better there?

I was also interested in fuel consumption on a distant trip,
Which is why I asked Seano11 what his truck did going back to
Canuckville.

If I recall, he stated 245 miles on about a half a tank of fuel.

As far as a smaller engine producing the same HP as its larger
brother, 25 years of engine development probably
has a lot going for it.

 

[jcappeljr]

I have trucks with both engines,My opinion is the same as Castle Bravos,I do like how easy the 8.3 starts,and it is quieter.

 

[seano11]

I think my next may have a 250 just to say I have one and compare the differences

 

[jcappeljr]

I have another truck for ya.Sean

 

[BKubu]

I agree with CASTLEBROVO and JCAPPALJR...the 6CTA has better top end power, but the NHC250 is better from a dead start. Unfortunately, top end power is not as important as power from a standing position, mainly because almost none of these trucks have any beans on the top end with the exception of the Freightliners and maybe the HEMTTs among the trucks I've owned.