Remember Cory? Running 38x15.5 tires, 6 speed, lots of power 8" lift.... 22 mpg.... Also capable of 2 gallons per mile.

 

I was going to keep quiet on this BUT.......Since putting these 35's on I'm actually getting almost 18 MPG combined driving. My truck just hauls me and the kids and an occasional dog(or 3). I used my GPS to correct the speedo and am very happy with the results thus far. I think having a six speed transmission has a big effect on mileage. I always shift below 2K RPM and now I can cruise 70 MPH at around 1700 RPM versus 2000 RPM before.

 

The best thing is a good running truck
Drive slow under 2000rpms and like you are100 years old and have no where to be
Where and how you drive make up 75% of mpg long hauls vs in town vs in the county can make 5 mpg change
Get the truck running 100% then look at mpg

 

I agree with speed & rpm playing a big part...
Ran 2500mi highway last week, consistently 10mph over limit, same results coming & going
In the northern states avg 17.4mpg @75mph
In the southern states avg 16.6mpg @80mph (2250rpm)
Hand calculated, all flat with same fuel stops both directions

I am guessing cruise control may hurt mileage as it seems to have much greater throttle movement to hold speed on overpasses where I would slow some going up and gain it back down.
But driving that long I wasnt going to stop using it

 

Ooops dbl post

 

I believe they are about on par with each other, with the ACs having the potential to edge out the ADs or ABs - because ACs have the ability to get the fuel in sooner (when appropriate).

To compare driving practice, the driver needs to focus on acceleration rate more than foot-fall rate. Rephrase: If you have always moved your foot a certain way to accelerate normal, you will likely need to retrain your foot because of tuning. If your tuning has a touchy throttle, this just makes good economy more challenging - but not impossible.

 

Thanks for the suggestions guys. What about a overdrive kit or something similar, don't know if possible but would keep rpms down on highway.

 

Maybe A New Test - PowerStrokeNation : Ford Powerstroke Diesel Forum

 

Do the math on how long that will take to pay for itself... Or just slow down, get behind a semi at a reasonable distance. If you have an egt gauge and or boost gauge you'll see your boost go down and your egts dramatically

 

John2001: FYI check out what Dave Whtimer said to me about lowering gearing to reduce rpms with my 4R100 automatic transmission (Dave's 2000 7.3L F350 2wd has a manual transmission ZF6):

Dave Whitmer calls my van an "Amish Barn." And he pm'd:

"I'm afraid you're screwed.
3.08s aren't available anymore.
3.55s might help but you're gonna have to slow down or face frequent automatic transmission failures. A GV would give you the same problem. Slowing down engine speed reduces ATF flow through the cooler and that cooks the tranny. GVs don't work in 4x4 and I've never heard of anybody driving any kind of overdrive in true 4x4 conditions. I don't think modern vans can be retrofitted with manuals. Dave"

"Back in the 60s they had three-on-the-tree trannies for vans but the shift linkages were long and temperamental. Big rigs have used "semi-automatic" transmissions (like paddle shift automatics but just no torque converter) for over forty years. We are starting to see those in smaller vehicles. VW offers a six-speed "dual clutch" tranny in the Jetta. You hit the paddle and it mechanically goes through the clutch shift routine for you. Formula One cars have used those since the 80s because they shift much faster than even the best driver. I'd recommend the 3.55s. Your 7.3 has plenty of torque to push big tires and a numerically low ratio. Dave"
. . .
"3.55s should be A-OK even with that Amish barn you are driving. The 7.3 has plenty of torque at low RPM. I commonly drive in the 1000-1300 RPM range. Watch your tranny. Maybe a tranny temp gauge might be a good idea. Dave"
. . .

I do want to explore the tranny issue some more, later though. (And of course, Mark Kovalsky's input on the 4R100 overheating at lowered rpm's discussion would be invaluable here.)

In fact, the thing I want to explore more thoroughly has just recently been done in a 4x4 van. Check it out here:

The Ute II: E350 RB 7.3 ZF6 - Expedition Portal

And math has never been my strong point...