towing mileage of trucks

2016 f350 dually with 3.73 gears pulling a 43' 5er averaged 8.9 over 1500 miles driving last week.

Truck is 6.7l diesel with delete kit running tow tune

larry barnhart wrote:

Cummins12V98 wrote:

rbcamping wrote:
I'm going to put my 2 cents in here. On my Dodge, I put 19.5s on it and had a slight gain in fuel economy when driving down the highway and towing. I had a slight drop in economy around town, they are heavy, but have less rolling resistance. There are a lot of factors that go into economy and engine efficiency is a big part. Blanket statements will surely get you into trouble.....Just my experience.

Did you calculate your mileage based on actual miles clocked, not what the odo showed?

Many different methods to check miles per gallon but only one way is correct. I have been shocked with some of my friends telling how they check mpg. Good old gallons into the miles driven, the old fashion way as Cummins does.

chevman

Speedo was re-calibrated and confirmed with GPS. So yes it is Accurate. Truck has 33" tires on it. It also has an Allison transmission. The gearing is 354s and the cruise RPM is around 1600-1700. The truck gets around 24-26 MPG on the highway. If I drop the speed down to 55 it jumps to 28-29.

2Macs wrote:
I have a 2007 Chevy Dually Diesel w/ Allison transmission that I tow a 37 foot TT with. I generally get 10 to 11 mpg towing on relative flat roads. Worse in the hills. My diesel mechanic has recommended that I add an Air Dog 150 Lift Pump to significantly increase my mpg as a beginning fix. Cost will be around $900 installed. He also recommends adding a EFI Live Duramax Tuner at a later date. Cost for this will be in the same range. When all is complete, he says I should get around 20+ mpg while towing.

Has anybody else completed these upgrades? If you have, what results are you getting and would you recommend this upgrade?

Maybe 20+ NOT towing, but NOT towing!! Well maybe I should correct that, I can get a reading of 99 mpg on instant mpg on the overhead console of our 2001 RAM CTD, going downhill with the PacBrake rumbling! :B

I think many people fail to understand that the right axle ratio for the job means the truck will downshift out of the overdrive gears when the task gets heavy. Its better to run high HP through 4th gear and slow the drive axle down a little with a 3.55 ratio rear end than it is to run that HP through an overdrive gear to speed the output shaft of the transmission faster only to slow it way back down in the rear end with a 4.30 ratio. The purpose of the overdrive gears are to slow the engine down for fuel economy when high power is not required. It's not a bad thing for the truck to downshift on the hills or even to lock out 6th gear when towing heavy. These trucks make so much torque that they can get a heavy trailer rolling without needing 4.30 gears.

Ford recommends an F350 dually with the 3.55 axle ratio for pulling 5th wheels trailers up to 27300 lbs. The 4.10 axle for 5th wheels upto 31300 lbs. A f450 is rated for trailers up to 32500 lbs. I would absolutely want a 3.55 axle for the trailer your considering. It's not a matter of 4.10 being better than 3.55 it's a matter of selecting the best axle ratio for your intended use.

My 98 with 3rd gen take offs for tires I had to add 5% to my miles driven then divide by gallons to be ACCURATE.

Cummins12V98 wrote:

rbcamping wrote:
I'm going to put my 2 cents in here. On my Dodge, I put 19.5s on it and had a slight gain in fuel economy when driving down the highway and towing. I had a slight drop in economy around town, they are heavy, but have less rolling resistance. There are a lot of factors that go into economy and engine efficiency is a big part. Blanket statements will surely get you into trouble.....Just my experience.

Did you calculate your mileage based on actual miles clocked, not what the odo showed?

Many different methods to check miles per gallon but only one way is correct. I have been shocked with some of my friends telling how they check mpg. Good old gallons into the miles driven, the old fashion way as Cummins does.

chevman

"The 17/18's now come standard with the 450 front end on the dually."

Are you saying the F350 DRW has the exact same parts as the F450 on the front suspension, brakes etc?

rbcamping wrote:
I'm going to put my 2 cents in here. On my Dodge, I put 19.5s on it and had a slight gain in fuel economy when driving down the highway and towing. I had a slight drop in economy around town, they are heavy, but have less rolling resistance. There are a lot of factors that go into economy and engine efficiency is a big part. Blanket statements will surely get you into trouble.....Just my experience.

Did you calculate your mileage based on actual miles clocked, not what the odo showed?

Cummins,
The 17/18's now come standard with the 450 front end on the dually.
I averaged 11.2 with 6k on the odom. and 3.5k of that towing the 14 Redwood GK38. Have not been on the scales with the new TV. (purchased 09/17)