Identical Trucks? Different MPG? Need help ASAP

[Sparks280zt]

Hey guys,

I dont post much here but I do alot of reading and lurking. Anyways heres the questions I have and need some input. I am looking at two trucks that are identical. They were owned by the same company and are speced exactly the same.
I have some pretty narrow criterie I need for my next rig, and there are only 3 in the whole country on truck paper that meet it. The problem is, one truck is in MT and the other in AZ. The MT truck is averaging 6.48 mpg per the CAT dash computer. The AZ truck is only getting 5.60 mpg per its CAT dash computer.

Now do you guys think this large difference is because of driving style?

The trucks are flat top t800s that weigh under 16k. They have CAT c13 430hp, 10spds and 3.36 rears. So for that set up in a t800, 5.6 seems very low.

So, in summary, do you guys think a conservative driver (I never go above 65) could get the mileage on the AZ truck into the mid 6s like its identical brother truck is getting?

Thanks!

[Orangetxguy]

Hey guys,

I dont post much here but I do alot of reading and lurking. Anyways heres the questions I have and need some input. I am looking at two trucks that are identical. They were owned by the same company and are speced exactly the same.
I have some pretty narrow criterie I need for my next rig, and there are only 3 in the whole country on truck paper that meet it. The problem is, one truck is in MT and the other in AZ. The MT truck is averaging 6.48 mpg per the CAT dash computer. The AZ truck is only getting 5.60 mpg per its CAT dash computer.

Now do you guys think this large difference is because of driving style?

The trucks are flat top t800s that weigh under 16k. They have CAT c13 430hp, 10spds and 3.36 rears. So for that set up in a t800, 5.6 seems very low.

So, in summary, do you guys think a conservative driver (I never go above 65) could get the mileage on the AZ truck into the mid 6s like its identical brother truck is getting?

Thanks!

YES is my vote...with a codicile.....how is the "rack"? Does the truck need an overhead run?

[Sparks280zt]

Im sorry Im not all that good with certain lingo.

What do you mean by codicile? and by rack?

Wow I sound like a newb.

Also what do you exactly mean by overhead run?

[Orangetxguy]

Im sorry Im not all that good with certain lingo.

What do you mean by codicile? and by rack?

Wow I sound like a newb.

Also what do you exactly mean by overhead run?

Codicile just means (a side note...a "However") Which were the things I wrote.

allan5oh is better at proper terminaology than I am, mechanicly speaking.

The "rack" are the injectors. How much smoke do you see...will you see. How does it pull on hills and under load.

The overhead is simply a tune up for a diesel engine. It usually includes adjustment of the jake heads.

[Bumper]

What are they showing for mileage on each truck and can CAT verify any previous warranty work done on them?

[marylandkw]

Now do you guys think this large difference is because of driving style?

It absolutely could be. I have seen as much as 2.5mpg swing before. Had a driver in a truck getting 5mpg, he said something was wrong and he could do no better. I drove it for 2 weeks and got 7.5mpg consistently. I wonder why I am a one truck company now?

If you are lucky allan5oh will stop by, he will tell you about every nut and bolt to look at and can tell you rpm's and stuff like that. He's one of them MPG junkies with a calculator

[Sparks280zt]

Thanks for all the replies, I am caling the CAT house right now.

[Sparks280zt]

Called the CAT house, everything checks out good. Truck has injector and warranty until 600k.

[Bumper]

You didnt mention price... is there a large difference between the two trucks and that is why your leaning towards the one in Arizona?

[GMAN]

You might also consider the type of loads and where they have been driving. If one has been hauling heavy loads and in a lot of mountains, then the mpg might be lower than someone who mostly hauls lighter loads in the plains. The driver is the single most critical factor when looking at fuel mileage. And those computers are not always accurate on the mpg they report. I have used them as a guide, but prefer calculating it manually using the odometer.

[Sparks280zt]

You didnt mention price... is there a large difference between the two trucks and that is why your leaning towards the one in Arizona?

Yes, there is a $8,000.00 difference between the two identical trucks. They were used by a flat bed company.

[rank]

driver can easily make 1 mpg difference. And as Gman mentioned, so can the terrain.

[no_worries]

The few folks that I know that have had exposure to them have nothing good to say about the C-13's since the first round of emissions came out. Just thought I'd throw that in

[allan5oh]

The MT truck is averaging 6.48 mpg per the CAT dash computer. The AZ truck is only getting 5.60 mpg per its CAT dash computer.

That could be the problem right there. Pen and paper only. Dash readouts will always be wrong, but they will be consistantly wrong. You cannot compare two trucks via dash readout, but you can compare the same truck one run to the next. You can tell if one run you got better fuel mileage, but that's about it.

[Sparks280zt]

Perhaps the c13 is not the best, no worse than a m11 right?

Anyways I hand calculated and i got 10.9 first tank and 11.2 second tank bobtailing back from AZ to NC. Pretty good, I had the cruise set at 66-67 the whole time.

[Bumper]

heck thats not much worse than my chevy silverado with the 454....

[Sparks280zt]

Yea the rig has some legs on her, at 66-67mph it was turning 1400 rpm. It is a real light weight truck (15,900) and is a flat top sleeper (less to go through the wind I suppose).