Ford 7.3 mileage, pure highway.. experience?

[lllateralus]

Since I have to commute 112 miles per day for a while in my 2001 F350 (picture below, for stance, and tire size) I filled up completely (topped off, full full), drove about 40 miles straight shot on the freeway. I kept the cruise control at only 60MPH, with a few variances due to traffic. Jumped off the freeway, filled up again, she got 15.3 MPG.

The truck has 103K miles, banks chip, banks cat back exhaust, banks trans command module, is in pristine condition and is impeccably maintained.

The truck has 3.73 gears, and was turning about 1600-1700 RPM almost the whole time.
The truck was barely working. The EGT was 400-450, turbo boosting hardly at all. (except up a mild hill or two, 5-10 PSI for a minute or two)

With a straight shot, low RPM and very low EGT's, I would have expected 17-19 MPG. Any comments?

 

[4671 Hybrid]

I think that's about normal since you're running a lift and have to tackle increased wind resistance. Was there an elevation gain on the route? Try running it both ways and see what you get but my guess is that you won't see 18 mpg. I hope I'm wrong but based on friends mpgs and my own when I was driving a similar platform (but not lifted), I don't see it happening.

 

[Tahoe Diesel]

My former, bone stock, 2000 7.3 E-350 van would average up to 19.5mpg on a long freeway trip. Don't forget the headwind/tailwind factor. Your lifted truck has as much frontal area as a van. I noticed a couple to a few mpg's loss on trips with a strong headwind.

 

[locrwln]

My 2002, with the 6spd on the last tank averaged 19.5 mpg (empty), which is pretty consistant since new on summer fuel. Mine is stock height, stock sized tires and I usually run it at 70 on the highway. The last tank was a mix of highway/city. Motor is stock except for a Ford AIS air filter and a Walker BTM muffler. No power adders. At 80 mph (all highway) it drops to 17-17.5.

Not sure why yours is that low. I wouldn't think the lift/tires would make that much difference at 60 mph.

Jack

 

[yfarm]

My 2002 7.3 hard top sportsmobile got 19-20 at 65 mph on interstate. 3.55 gears

 

[lllateralus]

With what seemed like such little effort from the 7.3 during that 40 (some odd) miles, I was expecting a minimum of 18-19!
It seemed like it was falling asleep, working so easily at such a low RPM. I wonder if the Banks chip is helping or hurting the low RPM, low boost mileage.

EDIT> also, The truck only has a 3" front leveling kit as far as suspension goes. (and Bilstein shocks, with Fox steering stab.)

 

[BCHauler]

From a guy with a 2001 f250 v10, I say " 15 mpg! droool..."

Lifting the front and running bigger wider tires can dramatically affect mileage. Lifting the front forces more air underneath the truck, greatly reducing the aerodynamic profile. If you took the 3" lift out and conversely lowered the front 3" from stock you would see quite a difference I bet.

Have you reprogrammed the speedo and odometer for the larger tires?

 

[UHAULER]

My truck is an 02 f350 sbec 4x4 7.3, auto, 3.73, stock, the only thing I changed was tires to 295/75/16. my speedometer is now accurate with the taller tires but the odo is off by 5% as checked by gps. I'm averaging 16.5 mpg combined city and freeway commute.

 

[haven]

Since it's not practical to remove the front suspension lift, it might be fun to experiment with a chin spoiler to improve aerodynamics. A sheet of aluminum, bent to follow the contours of your front bumper, could be attached to a couple of aluminum rods that would fasten below the bumper. This might get you the 2-3 mpg you're looking for.

 

[Regcabguy]

You guys are doing well. My friend's 2000 F-350 Supercab 4wd,auto,pizza cutter 265's,cab high Snugtop,and $7,000 worth of Bank's Powerpack,Banks TC and Trans Command has never exceeded 15.8 mpg. That's the best he's ever achieved and was on I-5 on a Northern Cal run from Encinitas.

Perhaps the Gale Banks stuff increased driveability but impaired his fuel economy?

 

[High Country Hillbilly]

I wouldn't be surprised if it did better at a slightly higher rpm range? What size tire are you running? Nice rig, seen it on here before. Looks like it may have more than just a nose job (leveling kit)...looks taller than that? (maybe not?) I have a 2000 / 7.3 / 4X4 / 6spd...has a couple things done to it (chip&exhaust, etc,etc)..If I keep it between 2000-2200 it gets 17-18 w/o a problem. At 60 mph...I'm not sure...have trouble driving that slow:smiley_drive:

Hillbilly

 

[Stoney126]

Do you have the banks tuned for tire size and gear ratio? What are you engine temps?

 

[DT75FLH]

My 02 with 4" lift 35" tires and banks turbo wheel, chip, exh would get 16 mpg on the highway.

I did see 19mpg 1 time. that was driving around yosemite for a week and the truck never went over 50 mph.

 

[Fish]

My '99 got around 15 stock. The Banks kit raised it to around 17. The 6" lift and 315's dropped it to around 12, especially in combination with the Callen. The Callen didn't really hurt it any more though.

 

[Redline]

I've done many MPG tests with all of my trucks since the early 1990s.

Your results do seem quite low for a 60-MPH test considering your high, 3.73 gearing, though I concur with all those that suggest a round trip, not a one-way test. A little more distance might be helpful too.

Variables in the real world can make a very big, but often temporary drop or spike in MPG, even on a straight freeway test. So a few, repeatable tests like the one you just did, will give you a much better idea if your results are 'normal' for your set-up or if your results were abnormally low on this one test. You do need a better baseline than a one way test. I've written whole articles about establishing a baseline but there are a few short words about baselines on my blog: http://www.roadtraveler.net

One thing you said was that you filled the tank very, very full. That's nice, but did you get the tank to the same level of very full at your second fill-up? This is very difficult to do, and you surely did induced a variable by using a different fuel pump. Not saying you did it wrong, just pointing out some of the common variables which can make a huge difference, particularly on a short test. And we are always limited by the accuracy of the fuel pumps. Everything matters.

Having said that, from a faded memory without digging out old notes... my testing with my 1996 Power Stroke with 4.10:1 gears and a 5-speed showed a surprising drop in MPG when changing tires from a 255/85R16 to a 285/75R16. Both tires were aggressive tread patterns and very similar in height, correcting for odometer error and all that stuff. With this heavy, armored, but 'empty' truck, MPG would go from from mid-high 17s to 15s, approx. 2 MPG at about 65-MPH.

--------------------------------------------

To heck with the memory, I like facts! I searched my computer and here is an excerpt from an article I wrote in 2006. The 285/75R16 tires being tested were Toyo MT. It was also hot summer, keeping the fan-clutch engaged and surely producing some additional drag:

On the first leg of the test the mile markers and trip meter indicated the odometer is approximately 2.5% slow with these big Toyos. The odometer indicated we had traveled 91.9-miles and we adjusted that reading up to 94.2-miles. Simple division indicated we only achieved 15.15-MPG. We were disappointed and a little surprised but see this as a graphic demonstration of the penalties of bigger tires.

Tires can make a huge difference, the size, weight, tread design, etc. I'm not a proponent of over-inflation (for the load). None of this is news, I've spoken to many light-duty diesel owners who have seen a dramatic drops in MPG going from a stock size tire (235/85, 245/75, 265/75) to a 285 wide tire.

I too am curious, what size and tire tread are you running?

Hope this helps.