Dude, That's BS.

If it isn't, turn Us all on to the magic pills.

 

filled up right off the highway, pretty much a flat straight shot, tires were inflated to 75/80 psi, plus filters and other maintence BS were just done. at 57 mph, 3.55/E4od, 327 miles by 11.4 gallons of fuel. I may be horrible at math but its not hard to punch those numbers into a calculator

 

Non-turbo IDI here: I have frequently averaged over 21mpg on long highway trips. The trips where you almost never alter speed unless you stop to pee or get fuel. I have never broken 23mpg (average), but I'm working on it. Going from Michigan to the east coast (CT, RI, MA, NY, PA) and back starting the 18th (next week), so we will see what the ole girl will do with the new 3" catback exhaust system on it. I try hard to fuel the truck to exactly the same amount every time.

 

Your number are off somewhere. In 10 years of ownership, 8 years of reading IDI forums, I've NEVER seen, heard of anyone getting over 22 with a stock IDI.

You prolly have a tank siphoning front to back, or back to front.

 

You need to average 3 tanks to make sure the fuel nozzle isn't shutting off too early. I nearly got fooled into thinking I got 35 MPG once. It bothered me so much that I went back to the cardlock and it too another few gallons bringing the average below 20.

However having said that, and knowing what my truck is capable of, I'm not going to dismiss ~28 MPG completely. The flatbed looks like it doesn't have any vertical walls on top or below it, so that could make it produce less drag then the OEM box.

cruising below 60 MPH also helps a lot to reduce fuel consumption.

Maybe try the other tank on the same run to make sure you are not siphoning fuel over to throw off the number (as if you have nothing better to do than shut up the skeptics LOL).

 

I know how to accurately figure mpg consumption.

As for your 10 yrs of ownership, and 8 yrs of reading, all I can say is to quote my father who rightfully told me, "a bricklayer can lay bricks for 40 yrs, and it doesn't make him a good bricklayer".

Oh, and by the way, I HAVE no 2nd tank to siphon from. My figures incidentally, were based on 2,200 miles of (continuous) driving.

 

Kleenax don't ever get rid of this truck.
What are you running for exhaust.
If I could get that kind of mileage I would not do the bio thing after you change to 3.55 gears you can sell the extra diesel you will be making to your friends. LOL.
Tell us more about the nitrogen in your tires. What is the purpose of this.

 

Nidrogen.....Hmmmm, my new tires don't seem to leak.

Yes, do tell.

 

He quoted MustangMan and his nearly 29 MPG claim. He wasn't referring to you. Your numbers sound reasonable.

Jason

 

Less moisture in the tire, which makes for a more predictable pressure change when the tires are at temp. AFAIK, the tires are not put under a vacuum, so there is no way to install 100% nitrogen.

And nitrogen is supposed to keep set pressures for longer periods because the nitrogen molecules are larger than oxygen molecules.

Works good in a automotive application where you stay at a constant pressure. But it would be hard in a pickup where you are changing PSI regularly.

Jason

 

I know about the stability of the nitrogen on the newer multi axle heavy haul trailers it is used in the air bags on the boosters instead of air never changes unless you change it.
I never heard of using it in tires though. I never change the pressure in my pu tires 80 psi and leave them. On a 4 wheelin rig that is differant though.

 

It's a NASCAR thing.....they use nitrogen in the tires and the impact wrenches they use on the tires.


I only get 13.25 mpg average with my non turbo IDI.......would love to break 20. Would a turbo make that much of a difference?

 

The Nitrogen, in all reality, doesn't do much for MPG. It just doesn't expand/contract like air does. So You jsut get a more consistent pressure. If Your like Me, check tire pressures every 3-4 days, You won't see any MPG difference.

I still say Kleenax's numbers are way off. I have a 7.3/sidewinder ZF5 also, I have the rotunda timing meter and have tuned this thing to the best MPG I can get. When I had My 4.10's, the best mileage I ever got was 17 MPG. That was unloaded, Traveling 65 MPH for 460 miles. Now,with 3.55's I can get 17 MPG, loaded, traveling 70-75 MPH

 

When I was driving my old highboy with a 6.9 4spd 4.10 the sped limit was 55 and that was mostly how I drove it I would consistently get 19 and 20 empty.
The best I have ever done with my 86 is 16 and it has a turbo and gearvenders.
Now the highboy was nonturbo but had tru duals with large pipes and the fuel was better those days.
Now the 86 has a dually kit not as good of fuel and single usually run 65 to 70 but has gv
and have played with the timing 16 is my best and it is on flat ground.

So what do you think makes such a big difference in the mileage.
I am thinking a combo of 10 mph faster dually and ulsd.

 

I had only read about it, but it was offered for free when I got new tires, so why not?

Here's a paraphrased blurb from an article that I read on nitrogen in tires.

Most tires are filled with compressed air, which when dry consists of about 78 percent nitrogen, 21 percent oxygen, and 1 percent other gases by volume. Water vapor (humidity) can make up as much as 5 percent of the volume of air under worst-case conditions. Filling your tires with nitrogen mainly does two things: it eliminates moisture, and it replaces skinny oxygen molecules with fat nitrogen molecules, reducing the rate at which compressed gas diffuses through porous tire walls.

That means, theoretically at least, that a tire filled with nitrogen retains optimal pressure longer, leading to more uniform tire wear and better fuel mileage. The commonly quoted figure is that truck tires inflated to 70 psi get 3 percent better mileage than at 55 psi.

Exhaust is a Banks Stinger Y-Pipe mated to (right at the Y) 3" stainless pipe running all the way back to a 3" straight-thru oval MagnaFlow stainless muffler, with a 3" tailpipe.

Ran stainless all-the-way, since I've put 2 of those regular steel ones on there and had them rust off in these Michigan winters! I got 2 - 6' lengths of 3" HD stainless (14ga) pipe for $4.00 at a yard sale, and the muffler was $90.00 delivered! Oh, and $56.00 for a MaganFlow lifetime warranty tailpipe made of 3" stainless.