MPG ?

G35Vortec454

Adventurer
My e250 4x4 conversion is complete (well, without fox shocks - next upgrade). It' a 9000# beast.

8mpg! Fully loaded.

Is that normal for a 4x4 5.8L (recently rebuilt, stock), E4OD, 4.10 gearing?

Next , I'm gonna advance thr timing to 13-14 degrees.

Thanks in advance for comments on the mpg.
 

Bbasso

Expedition Leader
Good grief, I couldn't handle that...
But more importantly, does your rig do what ever you need it to do? Like climb steep grades w/o issue?
 

G35Vortec454

Adventurer
Good grief, I couldn't handle that...
But more importantly, does your rig do what ever you need it to do? Like climb steep grades w/o issue?

9000lbs is pretty heavy. It has solid oak cabinetry, 2 gas tanks and a 25 gal water tank. Dual house batteries and a 3000W inverter. And the waste tank, which was/is empty when I weighed it. Oh, and I forgot the propane tank which has just a little propane in it.

I have not tested its 4x4 capability. I have only 100 miles on it after the conversion, on streets and freeway. It drives pretty good, it has a more comfortable ride than my 26ft Cummins 4x4 Class A motorhome. I have one unresolved complaint - the Quigley trackbar binding/hitting the upper web of the front axle housing (separate thread).
 
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G35Vortec454

Adventurer
Bumped the timing

The timing advance is now set to 15 degrees. It was quite difficult to find the middle-ground (13 or 14). Topped off the tank and test drove it.

I observed no knock at all. I didn't notice any change in performance either. We'll see, after another 100 miles, how the timing bump affects MPG.
 

ujoint

Supporting Sponsor
With only 100 miles on it do you feel the MPG calculation is accurate? Maybe check it and average out over a few tanks.
 

Bikersmurf

Expedition Leader
Seems a little thirsty... how are you driving? Above 55 mph economy will drop. Aggressive driving will also kill economy.

9000 lbs doesn't seem that heavy for rigs like ours. Ambos are all 9k or more.

On the highway I'll get more than double that... it being diesel shouldn't make that big a difference. Last highway jaunt I calculated it at 21 mpg. Around town it'll easily get 12 mpg.
 

G35Vortec454

Adventurer
With only 100 miles on it do you feel the MPG calculation is accurate? Maybe check it and average out over a few tanks.


Absolutely, I will be monitoring mpg over a longer haul. I was just surprised when I topped off my tank at just below half-mark! I said: ************************ where did the gas go? 12 gallons and I've just driven 100 miles since I last topped off (My rear tank is 22 gals, and front takes 18).
 
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G35Vortec454

Adventurer
Seems a little thirsty... how are you driving? Above 55 mph economy will drop. Aggressive driving will also kill economy.

9000 lbs doesn't seem that heavy for rigs like ours. Ambos are all 9k or more.

On the highway I'll get more than double that... it being diesel shouldn't make that big a difference. Last highway jaunt I calculated it at 21 mpg. Around town it'll easily get 12 mpg.

Yes, it is known that the Windsor 5.8s are thirsty under load and like to run at high RPM, out of overdrive. And it does rev really very well, sounds awesome, at the expense of mpg. For the 100-mile test drive, I drove it like that pushing it, flirting if it would even start to knock. It drives nice on overdrive, at the expense of driving in the slowest lane and everyone passing me.

So it seems there's a consensus that 8mpg is too low for other owners of a rig this kind around 9000#. My Cummins-powered 4x4 25ft Class A motorhome at 12,500# gets at least 12 mpg all day.

Nevertheless, for now, I accept the mpg is down at the bottom of the spectrum. I hope that with the timing bump and this next full tank will yield at least 10 mpg. But I won't be holding my breath. It is what it is :)
 

boardrider247

Weekend warrior anarchist
I'm not too surprised by 8mpg from a 351. My grandparents bought a brand new 1989 F250 2wd with that engine and it never saw over 11mpg it's entire life. And my grandfather was one of those guys with the little black log book that tracked ever fill up and all maintenance for his vehicles hand calculating mileage.
 

G35Vortec454

Adventurer
I'm not too surprised by 8mpg from a 351. My grandparents bought a brand new 1989 F250 2wd with that engine and it never saw over 11mpg it's entire life. And my grandfather was one of those guys with the little black log book that tracked ever fill up and all maintenance for his vehicles hand calculating mileage.

Thanks for the info.
 

Ranchero

Wanderer
Different beast (2006 5.4 E350 Sportsmobile), but I'm pretty consistently getting between 13-14mpg over the 7000 miles I've driven since I completed my swap in November. I haven't weighed, but I'm guessing I'm at about 8300 pounds now. I'm pretty happy with that considering winter driving on winter tires with winter-blend gas.
 

G35Vortec454

Adventurer
Different beast (2006 5.4 E350 Sportsmobile), but I'm pretty consistently getting between 13-14mpg over the 7000 miles I've driven since I completed my swap in November. I haven't weighed, but I'm guessing I'm at about 8300 pounds now. I'm pretty happy with that considering winter driving on winter tires with winter-blend gas.

Thanks, your 5.4L is a known improved motor, esp. on mpg. If my 351/9000# gets 10mpg, I'd be happy.
 

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