Question: Mileage while towing

GMC_2002_Dmax

GMC_2002_Dmax

The Still Master
Feb 15, 2008
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Charleston, SC
www.ridgerunnerdieselperformance.com
I have a question for those that tow heavy loads.

Hypothetically if you had the following tow vehicle what would be your expected fuel mileage under this scenario.

Kodiak Topkick 4500 running the LLY/LBZ motor, empty weight is 12,500 lbs, gears swapped to 3:73 and tows in high elevations at speeds between 65-75 mph.

Average trailer weight is 6000-10000 lbs, weights go as high as 12K for towing with a gross of 24K lbs.

How much will winter vs summer diesel affect fuel mileage ?

How much will 10-15 degree temps affect fuel mileage ?

How much will high elevation affect fuel mileage ?

How much will headwinds affect fuel mileage ?

Thanks
 
Last edited:
Harbin_22

Harbin_22

Active member
Dec 4, 2010
3,858
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Southern Indiana
Got a local guy with a crew cab 4500 with a 30' aluminum stock trailer. Stock gears with an edge juice box. Not sure on total weight, truck has an aluminum flat bed. Guessing truck and trailer together around 12,000-13,000. He ran half trip empty and half trip with around 5,000 in cows. His average was 8.75mpg around 65mph on that trip. Anywhere from 500'-1000' elevation on winter fuel. Don't know if it helps you any but nonetheless it is a figure. It is an LLY too.
 
GMC_2002_Dmax

GMC_2002_Dmax

The Still Master
Feb 15, 2008
1,748
8
38
57
Charleston, SC
www.ridgerunnerdieselperformance.com
Chevy1925 said:
Id say between 9-10mpg. Why the question though tony if you dont mind me askin?
Click to expand...

I was asked by a shop to tune a vehicle like this, the owner is claiming that he used to get 10-12 mpg towing and 17 mpg empty.........I don't think that mileage like that was possible, so I figured I would ask what is reasonable or expected.

He is getting 5-6 mpg towing and around 10 mpg empty and he calculates his previous mileage by "knowing" how far it is and "estimating" how much fuel he is using.

He has a 40 gallon stock tank and a 90 gallon transfer tank and never keeps accurate fuel logs, also his speedo is off 7-8 mph, reading slower and I asked him to use GPS mileage vs the dash mileage for accuracy as well as keep very close tabs on his actual fuel consumption.

He is calling me constantly to tell me how bad his fuel mileage is compared to what he was getting prior to me tuning it so I asked him to restore his previous tunes........he called me today to say he's getting 5mpg with his old tuning if I heard his message correctly..........????

So before I call him back I wanted some opinions.

:eek:
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
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in the buckeye state
GMC_2002_Dmax said:
I have a question for those that tow heavy loads.

Hypothetically if you had the following tow vehicle what would be your expected fuel mileage under this scenario.

Kodiak Topkick 4500 running the LLY/LBZ motor, empty weight is 12,500 lbs, gears swapped to 3:73 and tows in high elevations at speeds between 65-75 mph.

Average trailer weight is 6000-10000 lbs, weights go as high as 12K for towing with a gross of 24K lbs. so max gross of 36k?

How much will winter vs summer diesel affect fuel mileage ?2-4mpg drop

How much will 10-15 degree temps affect fuel mileage ? i wouldnt know have monitored it...

How much will high elevation affect fuel mileage ? i saw 2mpg drop between the midwest and wyoming.. in july/august

How much will headwinds affect fuel mileage ?how much head wind? how much sail is the load? i have had it cut my mpg by 40% or more even after i slowed down.. had a 25-30mph full to 75% head wind i slowed to 60mph from the 68 i normally run coming from rideland WI to KCMO avg 6.25mpg

Thanks
Click to expand...

granted im running 4.63:1 with 32.5" tires and a .75:1 od, cruising are 2300-2500rpm and tuned for that..
this was the load from WI to MO the dumpster only weighed 7,000 gross was 20,000lb
163313_4835492358755_1691131378_n.jpg


hope that helps...

last time i saw johnny i asked him is mpg avg was 15 just dding with 5.13 and 40" tires that was 08
 
Chevy1925

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
23,038
8,064
113
Phoenix Az
GMC_2002_Dmax said:
I was asked by a shop to tune a vehicle like this, the owner is claiming that he used to get 10-12 mpg towing and 17 mpg empty.........I don't think that mileage like that was possible, so I figured I would ask what is reasonable or expected.

He is getting 5-6 mpg towing and around 10 mpg empty and he calculates his previous mileage by "knowing" how far it is and "estimating" how much fuel he is using.

He has a 40 gallon stock tank and a 90 gallon transfer tank and never keeps accurate fuel logs, also his speedo is off 7-8 mph, reading slower and I asked him to use GPS mileage vs the dash mileage for accuracy as well as keep very close tabs on his actual fuel consumption.

He is calling me constantly to tell me how bad his fuel mileage is compared to what he was getting prior to me tuning it so I asked him to restore his previous tunes........he called me today to say he's getting 5mpg with his old tuning if I heard his message correctly..........????

So before I call him back I wanted some opinions.

:eek:
Click to expand...

Oh i see! Ill shoot a message over to johnny to check this thread out.
 
Gasuout

Gasuout

Johnny
Mar 20, 2008
2,188
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0
Santa Ana , Ca.
Ive heard of no kodiak getting 17 mpg .

It is possible to get 10 mpg towing if you keep your rpm down to about 1900 rpm average and depends on the weight your trying tp pull .

Most kodiaks get 7-9 mpg period . Depending on the right foot of the operator .

Ive towed my 50 ft flat bed empty to colorado and got 13 mpg there and 11 mpg loaded with 1 truck coming back .

I average 10 mpg for the most part whatever im doing ... hauling ass ... street thrashing ... towing .. pretty much an average when I actually even check .

The only way I could get 15 mpg is a slow roll in the slow lane at maybe 60 mph max empty . :thumb:

I really doubt your tuning is causing it to get 5-6 mpg ... only the driver causes that low a mpg ... or a issue unrelated to the tuning id guess .

Tuning is tuning and any basic tow tune or even a race tune would get you the same mpg . I run my kodiak on my race tune pretty much 247 and even tow with it light pedal . If im towing a long distance loaded down I put mine on a healthy tow tune . Other then that ... my best mpg is on my race tune babying it .
 
S

SmithLBZ

New member
Jan 11, 2012
91
0
0
TN
I have a 05 Lly 4500 4x4, with the 5.13 rear end, single cab, with a 12' flatbed. single Efilive tune, 5" exhaust with muffler. K&N intake, egr del. , 245/19.5 tires. cruising around unloaded on hwy it gets 15-16 mpg.12-13 in town.

Towing our toy hauler which is at 10k, it got 8-10 on hwy

...granted it is gearbound on the highway, but if you try and keep it close to 2000rpm or under, or under about 55mph is where it runs best.
 
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