what are you getting for MPG on your duramax?

O

oonighttrain

New member
Joined
Sep 3, 2006
Messages
17
i just got a 04.5 crew cab 4x4.. seems to be getting about 13.5 mpg, thats with mostly highway driving.. shoiuld it be getting more?

i have a bully dog intake and cat back exhaust, 295/70 tires and 3:73 gears...
 
Are you calculating your mileage with a correction for your tire size?
 
Is that off of the DIC or hand calculated?

I averaged mine today a whopping 12.5mpg around town, dam I hate this winter ULSD. Maybe a fuel filter change(only 5K on it) & oil change is due.
 
no, i hand calculated it.. right at 13.06 mpg...

this is the first diesel i have had but, i sure thought i would get better economy than this!!

i drive 90% highway miles.. you think changing the stock tires could possibly make this much difference??
 
What are 295's I think they are 33's That is a big tire. Measure from the ground up

My truck is putting 400hp down and I have 285's last road miles I checked I got 19.19 mpg
 
oonighttrain said:
no, i hand calculated it.. right at 13.06 mpg...

this is the first diesel i have had but, i sure thought i would get better economy than this!!

i drive 90% highway miles.. you think changing the stock tires could possibly make this much difference??
Click to expand...

If your truck isn't calibrated for the larger tires your speedometer is at least 8 mph off (to the low side) it says 65, you're going 73 or more. Since your speedometer is slow, that also means your odometer isn't accurate either (reading less miles than you're actually putting on)
 
BUCKSHOT said:
What are 295's I think they are 33's That is a big tire. Measure from the ground up

My truck is putting 400hp down and I have 285's last road miles I checked I got 19.19 mpg
Click to expand...


they are just over 32 inches tall... about 11 inches wide..

im gonna look into a programmer.. hopefully that will help!
 
turbojoe said:
actually 295s are 34", 285s are 33", 315s are 35"
Click to expand...


Same thing I was thinking? Your odometer is off by about 10 per cent. Also with winter blended fuel and this crappy ulsd you will be off some.
 
oh, i looked at my tires.. they are 285?75/16..
according to the manufacturer, they are 32.68 inches tall..

i see that that can throw my speedo and everything off..

how to i get all that stuff back in order? programmer?

if so, will a bully dog power pup do it?

thanks
 
Almost any hand-held programmer will recalibrate your speedometer (hypertech, predator, etc).
For what its worth, by my calculations, you're getting about 16.2 mpg
 
I'm getting anywhere from 15-16.5 ..but then again I drove iit like I stole it most of the time..:hehe:
 
partsguy662 said:
For what its worth, by my calculations, you're getting about 16.2 mpg
Click to expand...


not unless im a total moron (very possible)..

i was almost on empty and put just over 22 gallons in it.. trip meter said 286 miles... comes out to about 13 mpg...

:doh:
 
oonighttrain said:
how to i get all that stuff back in order? programmer?

if so, will a bully dog power pup do it?

thanks
Click to expand...

Most of your Programers will correct the Speedo I don't think the Power Pup will.
 
oonighttrain said:
not unless im a total moron (very possible)..

i was almost on empty and put just over 22 gallons in it.. trip meter said 286 miles... comes out to about 13 mpg...

:doh:
Click to expand...

Your math is right....but your miles are wrong..Remember, your speedometer is calibrated for 245/75R16 tires....You have 285/75R16 tires on your truck.
So, when your odometer says you put 286 miles on, in reality you put on about 343.2 miles. :)
 
My crystal ball never lies....:hehe:


Actually:
Speedometer Adjuster (with oversize tires)
(New Tire Diameter / Old Tire Diameter) * Speedometer MPH = Actual MPH
 
thanks parts guy!

next thing is performance stuff.. i have already put on a bullydog intake and cat back exhaust(doesnt make any difference in the sound)..

looking for mods that will not make other stuff break! lol.. :ft:
 
Checked mine this weekend. Got 18 on mostly 2 lane hwy @55-60 MPH. 16 on the interstate @75-80 MPH & 50 miles of in town driving.
 
You must log in or register to reply here.
Back
Top