ok let us beat the mpg horse some

[Clb]

Eta
61k factory miles.
aftermarket ats 093
3" downpipe
Holly red no regulator
Zf 5 sp. 4x4 , 4.10:1 lsd single rear tire
Stock spec tires
Pullind a dry 6k 5th wheel loaded sparcley on mostly lo land rolling hills ans flat Valleys.

stock EVERYHING ELSE.


So every mpg thread here gets derailed into a performance category .....

That said
Details of my whine are as follows
I got this junk with documented @ 30 something k miles in so cal, best mpg babying it up the 101 was 14 ish empty that day, fast forward 25k miles later, and the towing mpg just kept dropping from a best of 10-12 tojust before I put in a new pump of like 7...
I swapped to brand new delphi bb codes from Russ @ maybe 40 k.
at 60k I put in a r&d 80-90
timing At 7 At 13# boost,runnin empty @ 75 highway got 12.4 mpg oh joy...
then bumped the boost to his recco of 15# @7 deg, no change.

I tow the exact same route with the 6500# 5er every time for this discussion...
It is around a 120 mile round trip I usually burn 1 tank.
Best mpg has been 8.41 worst around 7
I have tried 7 degrees and got 8.41 then I tried 8.9 and got 8.11.
Driving style is nursing it for mpg.
I did 1 run playing with all of justins glory of calibration and fuel delivery and lets just say I aint posting that mpg as ford would puke...

So what am I doing wrong besides beleiving the net warriors fantastic mpg claims?


what do you tow and how many #'s?

 

[KansasIDI]

Here are my numbers


1991 Ford F-Super (F550 basically)

ZF5 and 5.13 rear gears, 225/70R19.5 tires

Just a tick under 80k kilometers (50k miles, truck is from Canada and has communist/metric dash), engine has high hours and doesn’t score particularly well on an oil analysis…

7.3 IDI with what was once a Moose 90cc pump that I have fiddled/tampered with to max out

7.3 PSD electric lift pump, regulated to 6 psi, which it holds constantly

ATS 093 (Ford factory kit) that has exactly four original parts left, those being the two halves of the airbox, the oil feed manifold, and the Y pipe, which has been modified by our good friend IDIoit (Brian) with a V band that connects it to the sweet stainless bellowed up pipe that he made. I also have R&D (Justin) stage one spinning whistle and 3” V band downpipe conversion, feeding into 3.5” with a flow through muffler, and a Hypermax intercooler kit to round everything out.

In other words, lots of air, lots of fuel, and lots of weight.
(Last time I weighed truck with tools and equipment that I keep with me, 15.5k lbs)

Have pulled 30k lbs several times, props to hydroboost and disk brakes on all four corners.

Most of my driving is two lane highway in the Great Plains 55-65 mph, mostly at 65, which runs my truck about 2600 RPM, and 11-12 mpg

City driving, 20-45 mph, and interstate, 75-80 mph, tend to yield comparable mileage, 8 or 9 mpg.

Towing at any speed above 10k lbs yields similar mileage numbers, pretty much regardless of speed.


Here are some anomalies of my truck

I have the timing set real far back, 3* @ 2000 RPM

(Side note, truck does not smoke above 1500 RPM or above 1 psi of boost at full pedal)

18 psi wastegate setting (on stock head bolts and gaskets, and all this with factory NA rods, probably dumb but I have 4 spare engines so whatever)

And probably most noteworthy of my truck’s idiosyncrasies, I have a set of Russ’s injectors, but I had him set them at a higher pop psi than normal, so who knows what that does. Probably not much, but I know that when I switched out the injectors, the engine sounded entirely different. I reset the timing when I changed the injectors, so just the higher pop pressure seems to have made the difference. No noticeable difference in performance, mileage did improve from this change, but only marginally, 1-2 mpg.


From what I have heard about R&D’s pumps, that would be my first guess on your fuel economy.



In what manner do you cram your air in? What are the dimensions of your exhaust tubing, do you have an intercooler? What is your lift pump psi, does it hold steady or fluctuate with demand? Do you have cupholders? There are many factors that can influence fuel economy.

Edited to add tire size

 

[Clb]

Interesting read.
I'm going to dispense with the BIG question for the peanut gallery first.....
Do I have cupholders?
The factory 93 xlt extra cab console has 2 soda can sized holes in it.

 

[Clb]

I'll be back...
Bone stock 93 in my sig line with an ats 093 and 3" downpipe.
I think ?3" ? factory exhaust with muffler.
No ic yet but Brian's holding an air to water for me.
Holly red no regulator.
This **** acted the same with the factory original pump with sub 60k on it.
So I'm leaning towards the injectors, as I've babied this **** ( both pumps) to no avail.

But if I tromp on it I can use the fuel needle as a backwards speedo, boucoue happy juices flowing from the tank, the man has tallent.

I need to have Justin build me a new center section due to the filter getting clogged by a rat last spring and me putting 200 miles on it before I noticed it.


More to follow

 

[Indadesert]

1990 f350 cclb 4x4. 33s E4od 3.55 gears 7.3idi banks waste gate. I almost never run empty but when I do I get around 23-25mpg on flat ground at 60mph in 4th/OD Usually towing the 10.5k horse trailer around 12min at 55 in 3rd. Remember speed kills. The speed limit back in the 80s-90s was 55 and too going it was 45. So slow down. Wind resistance is a very real thing.

 

[Black dawg]

Have not checked any real mpg numbers for a long time, but rarely get less than 200 miles per tank before switching pulling anywhere from 5-10k.

Last time I checked mpg, was pulling empty trailer at 80 for 5 hours, seems like that was about 15 3.55 gears.
And yes, most people are full of it when they claim a mpg number.

 

[Clb]

1990 f350 cclb 4x4. 33s E4od 3.55 gears 7.3idi banks waste gate. I almost never run empty but when I do I get around 23-25mpg on flat ground at 60mph in 4th/OD

what size tires?

Usually towing the 10.5k horse trailer around 12min at 55 in 3rd.

12 mpg?

Remember speed kills.

Sold that tee shirt

The speed limit back in the 80s-90s was 55 and too going it was 45. So slow down. Wind resistance is a very real thing.

Please proofread this ^^^

I'm maxing out @ 65 so I don't get rearended daily.

Have not checked any real mpg numbers for a long time, but rarely get less than 200 miles per tank before switching pulling anywhere from 5-10k.

Last time I checked mpg, was pulling empty trailer at 80 for 5 hours, seems like that was about 15 3.55 gears.
And yes, most people are full of it when they claim a mpg number.

Wish I was anywhere near ya'lls boat.
25 mpg is what my civic gets.
Towing @ sea level I'm @150 miles a tank.
And Yes
I'm 100% certain that the mpg # thrown around are not certified speedometers.

Thanx guys

 

[Black dawg]

Im assuming factory turbo truck, does it still have the stock down pipe and outlet on the turbo?

 

[Clb]

So
What am I doing wrong besides believing the keyboard warriors extravagant mpg claims?

 

[Clb]

Im assuming factory turbo truck, does it still have the stock down pipe and outlet on the turbo?

 No
No and no
Not a factory idit
Aftermarket 093 ( no ford bump for power loss) and 3" downpipe.

 

[Jesus Freak]

I run on WMO......my speedometer doesn't work, so my odometer doesn't work, I basically pay nothing for fuel, so if I get 6mpg, it doesn't matter, but I "feel" like I get 12-15mpg, but that's baced on emotions not facts.....good luck keeping this scientific, I promise not to derail the thread with a discussion of "performance".....my N/A 7.3 dually doesn't "perform".....it does "go" though......i "feel" that it goes well....

 

[ColLonewolf]

7.3 PSD electric lift pump, regulated to 6 psi, which it holds constantly

How do you achieve this?

 

[KansasIDI]

How do you achieve this?

The 7.3 PSD pump makes 55-60 psi unregulated, so it holds 6 psi with a regulator just fine

 

[ColLonewolf]

What regulator did you use?

 

[Black dawg]

What boost and egt do you run with trailer steady speed and flat ground?