My dad has a F250 Harley Davidson with the 6.0 and he is getting 13 mpg all the time. I installed a intake, exhaust and a Diablo Sport programmer hoping to increase the fuel mileage but it all stayed the same. Any word on what is going on. He is looking at a 07 Duramax, and I dont want him to go that route. I have a 7.3 and I am getting 20 mpg on the highway. I told my dad to figure up the mileage on paper and he said its only about two tenths off. Any Ideas. Oh and the truck has a butt load of power.

 

what is the mileage on the truck?

 

he only has 28000 miles on it

 

TMLS? This affliction typically attacks the right foot.














T.M.L.S. (To Much Lead Syndrome)

 

I think some additional questions need to be asked to make a fair assessment.

You say, "getting 13 mpg all the time". Are we to assume that is combination mileage (i.e. a mix of both city & highway driving)? If so, can you give us a rough percentage (ex. 70% city/30% highway)?

Being from Wyoming myself, the area that he drives in could be to blame, as well. It is no secret how the entire Eastern & Southern portions of the state gets hit with high winds. Along the same line of thought, maybe he's pulling South Pass, Sand Draw, or one of the other various grades frequently.

Driving habits will make more difference than anything else. Slow acceleration. Coasting to time lights. Limited braking. Keeping the RPMs at or under the 2,000 RPM mark. All of these will help out on the fuel economy front. If your dad is anything like my dad, or myself for that matter, he might be his own worst enemy when it comes to fuel economy.



The harsh reality is that you cannot change physics. Your dad still has a ~7,800+ pound Super Duty with the rough aerodynamic characteristics of a brick. Even with the best engineering, it is still a balancing game between performance & economy.

The modifications that have been done are not going to do anything positive for fuel economy. If by some fluke you could get a minor improvement, that improvement would be negated the first time you tapped into the additional power offered by the chip to pass someone, merge with traffic on the highway, etc.

I will go out on a limb on one particular thing, and say that the aftermarket air intake was probably a bad decision. Don't take that personally. Hell, I was looking at going down that road on both my previous & current 6.0L-powered Super Duties. Thankfully, I found this site & started reading threads...a lot of threads...over the course of the past two years. Ford, International, and Donaldson did a great job with the 6.0L intake system. There are quite a folks here that will atest to that. Bottom line, unless you are making competition-level horsepower, an aftermarket air intake system is just increasing the likelihood of the motor injesting fine particulates. The most common early warning sign is "dusting" of the fins on the inlet side of the turbo.

 

I am still at 13.5 MPG...06 6.0 Lxt CC. That is 13.5 in the city... 13.5 on the Hwy... 13.5 over 2000 RPM... 13.5 Under 2000 RPM. Have 7000k on the truck. Not complaining but just putting my information out there. Did not buy it for gas mileage although I did expect better... bought it to haul my kids and laptop to work and soccer games and look cool doing it! Love it. Sorry to jump in on thread but thought info might help.

 

Well he is running the truck on the interstate and puts the cruise on 80 and doesn't touch it. He runs from Sheridan Wyoming to Gillette wyoming and its 104 miles one way. He does this every week. My brother has a 6.0 also that is stock and follows my dad at the same speed and gets 17 mph.

 

Have an 05 6.0 and had same concerns only getting 13 to17mpg then put some miles on truck now consistant 20+ hwy and 15 in town

 

how many miles do you have on your truck now?

 

Keep in mind that he is pushing a near 4 ton brick down the highway @ 80 MPH.

With that said my '04 4x4 SC Longbed w/ Diablo Predator set on 65 H.P. consistently got 13.5 MPG in city & 16.5 Hywy with the cruise set @ approx 78 MPH.

 

Have almost 20,000

 

Well, I traded in an '05 Lariat F-250 for my current '06 Harley F-250. I dropped a solid 1 MPG making that move. Beings that I drive the same way and the trucks were equipped very similarly (CC, SB, 4x4, 6.0L w/TorqShift, 3.73 LSD, etc.), I have to assume that the extra MPG went to rolling the bigger, heavier tires & rims of the Harley package. In the city (Denver), I went from a consistent 15.5 to steady 14.5 MPG.

My highway mileage was pretty similar, but I was also playing with how fast I drove on my trips between Riverton & Denver, and that is where I noticed how the "taking her slow & steady" philosophy paid off. I've managed to hit 20 MPG by setting the cruise at 65 MPH. At 70 MPH, I can get right about 18.5 MPG. And, at 80 MPH, I am looking at 16.5-17 MPG. Needless to say, it drops off pretty quickly from there. Which is kind of sad, considering how fast traffic runs between like Fort Collins & Denver.

Bottom line, the trick is in keeping the RPMs in that 1,800-1900 RPM range....the sweet spot in the power band.

 

People that drive at 80mph should not complain about fuel economy. Driving fast and getting good economy are mutually exclusive. The aero drag anything experiences is a squared function. Meaning: 80/70= 1.143
1.143x1.143=1.306.
So although driving at 80mph is only 14.3% faster than 70mph, you experience 30.6% more aerodynamic resistance.

 

I have just under 52,000 & the truck is bone stock with the only exception a Superchip now set on the Economy(mid) level.
At a steady 75 on the highway I can average 18.1 to 18.4 (calculated- not the overhead), and in town averages 14.8 to 15.6, dependent on traffic!
I have noticed a decrease on overall mpg with the new low sulphur Diesel, but I have learned to be a bit more easy on the right foot!
The truck has slowly increased in mileage since I bought it, and I have been using Blackstone oil analysis on every oil change since 19,000 miles and ell reports have been good.
I have been running Synthetic oil (Royal Purple) untill the last change when I changed to Rotella due to the $$ (availability at Costco and Sam's Club)difference, and the only difference I have noticed so far is a bit louder cold start clatter.
Is seems these 6.0 Diesels get better with age.
Good luck on the mileage,
John Russell

ps. I Loved the High Performance tune, but the mileage dropped 2 1/2 mpg immediately, so I changed to the economy ahd have been happy since!

 

I have to agree with the aerodynamics involved. I pulled a 26', 8500 GVW fifth wheel with my '05 F-250 CC 4X4 PSD TS numerous trips, cruise set at 75 mph on the NM interstates. I got about 10 loaded this way. I now pull a 38' 16,000 GVW fifth wheel, with the cruise set at the same 75 mph, I still get the same mileage, average 10 loaded. A 30 mph head wind resulted in a drop to about 7 mpg! Mixed driving I average 16.5 unloaded. Weight doesn't seem to affect the milage nearly as much as the wind resistance. I have also dropped the speed to see what, if any difference it made. With the cruise set at 60 mph on the back country two lanes I get as high as 18.5 mpg, running empty. I also tried it pulling the fifth wheel, cruise set at 65 mph for about 250 miles, I got the same 10 mpg. Just more food for thought.