I have 4:10s so Im 2K rpm at around 67 mph.

 

I have 373"s, but usually I run around 67MPH on the freeway, just not in a hurry anymore.
Speed defiantly makes a difference on mine, going from 65 to 75 makes a noticeable difference in GPM.

 

I agree.
My problem is that my wife and I travel about 750 mi each weekend from east TX to south TX - our commute - with a 73 mile stretch (each way) legally at 80-85 mph, talk about suck down the dead dinos. Normal trip takes 6.5 - 7.5 hours, depending on pee and Cabela's stops. It's tough to slow down when your just ready to get there.

 

Sounds like you need a little car for the commute,, but they just suck.

 

You must be clairvoyant, I bought a Subaru Outback
Ok, more specifically, a dog hauler. Three dogs that make every move that we do. The Subi hauls all of our crap and the dogs and gets about 26 mpg. I prefer my F350 SRW. But dang it has gotten very expensive to operate. BTW the dogs are kid replacements....we probably need psychological assistance.

 

I think the Subaru might be a little small for Mine> the wife, her sister, and my daughter show ours, except the lab, she's our rescue dog. Anyways she uses our 99 E250 as the dog hauler. Here is a picture of the group, sorry it's a little old but the only one I could find with all of them together. LOL, they weren't very happy at this photo shoot.

 

Maybe if you taught them how to drive...just sayin'. They're a lot bigger than my group.
I've got two smalls and a large rescue "AAD", All American Dog, that likes to ride on top of the lil dog kennel with her head on my shoulder. The F350 is a perfect fit for her.

 

I fill the tank till I see the fuel in the neck and then I know to repeat that benchmark at the end of the trip,do the math etc.I got 17mpg's on a vacation [1100 miles] lot's of highway no trailer . but I just finshed a 3week vaca with a 25' tow behind toyhauler with a upper rear bed[lot's of wind resistance]@6,500 lbs total weight and could not do better than 9 mpg! wind was a definite factor on over half the trip [Ca. to Ar.] 3.73 rear 4x4 crew cab banks tuner set on econ. my suspicion is the trailer tires were one rating below what they should have been? when i bought the trailer I took the wheels up to the store and asked for replacements ,I should have consulted the dealer about the proper tire . I can honestly say that I passed a few people on hills though! she is not lacking any power and I have this stinking obsession to get 12mpg's with this trailer and truck or else .......Well I can't bring myself to say it

 

I would be in the same boat except I can only avg about 13.5 on a trip (350 mi commute) because of our liberal speed limits and at 75-85 with a lil headwind any better mileage for me is nearly impossible. I may change over to 3:08 axles but that may affect my 5th wheel towing

 

Perhaps if you picked up a cheap set of wheels and put somewhat oversized tires on them you could get the best of both? Put the oversized on for notmal driving and get the same effect as the ratio change, and when you're going to tow heavy put the stock size on. That would seem better than being stuck with a new ratio all the time.

 

Utterly brilliant, I like the way you think!

 

One thing that I noticed about the 6.4 tuning, is that it builds crazy boost sometimes, for no reason. Sometimes it seems like a 20% increase in throttle results in boost taking off super high. I disconnected my turbo actuator, and have been driving it for a long time like this. The boost now reflects actual load better, not computer calculated boost.
Using with the spartan tow tune.
With the turbo connected, this truck was always at 10 - 20 psi of boost, and now it runs like 3- 10psi normal driving. EGT's fine. MPG's up.

 

One note on this: If your truck has it's emissions system intact I would not try this. One reason for the variable geometry turbo and high boost is to reduce soot production (i.e. pack enough air into the cylinders for a clean burn).

If you do this with an intact emissions system you will almost certainly see much more frequent regens, higher resulting fuel consumption, probably higher fuel dilution of the oil and potentially a clogged DPF.

 

If I decide to have more brave than brains and unplug with no other mods I'll let you know the end result.

 

Yeah don't even try it on a stock truck, or tuned with DPF on.
Disaster could be the end result.

The 6.4 uses so much EGR that if you disable the turbo, the combustion will be severely lacking clean air, so it will gum everything up and probably run like absolute garbage.
The DPF on tunes control the air intake and EGR intake to burn clean, and if you disable the turbo, it will no longer do that, and likely the truck will run like junk for a short time until the DPF is destroyed.

On a tuned deleted truck, the engine is getting 100% fresh air, instead of EGR mixed air, so the truck runs decent without the turbo actuator hooked up.

One more time, don't mess with the turbo actuator if the DPF is on the truck, or the EGR is operating. Bad idea.