I have all kinds of aftermarket goodies (to long to list) that make unbeleivable power and generally maintaining close to stock MPG on my 2003 6L when driven and maintained properly. Currently I have 80,000 miles.

However in the last generation of trucks with HP and torque wars between the big 3 not to mention the increased emmission restrictions the fuel economy has severly dropped in the latest generation of deisel trucks and appears to get worse.

About 3 dozen of my companies and friends 1998 to 2002 vintage 7.3L powerstrokes and 5.9 cummins get in the range of 25MPG HWY and 20MPG City empty. Loaded they still get better fuel milage than our new generation trucks empty. Our 6L and new HO cummins get in the range of 18 MPG HWY and 14 MPG City (empty).

I know many of you love the added power but for some us like my self I want to maximize fuel ecomony back to the good-o-days to acheive the MPG we once use to get. Even if this mean losing significant power back to older generation trucks once had as I was satisified with their power and particularly their proven durability.

Being relatively new to the forum I would appreciate any advise, directions and etc on how I can achieve this on my 6L as I have not seen a post on this topic.

I know of gains of 1-2MPG such as tires, gearing, erodynamics and etc. but I am intersted in signficant gains >+5MPG and strictly with DETUNING the 6L engine so my 2003 PSD has the same truck characteristics as my 2000 PSD (comparing apples with apples).

There appears to be an unbeilavable amount of expertise and knowledge on this forum and I would greatly appreciate your help.

 

I think you are partially right. If you look at the Compression ratios of diesels they have been going down in a search to produce more power and torque by upping the boost produced by the turbocharger. This has definately cost us some MPG. The other thing to look at is wieght. All the manufacturers are chasing higher GCWRs as a selling feature of how HD thier trucks are. This also has a significant effect on MPG. It will be very hard to attain the MPG what is was becuase of this last fact, just basic physics.

You are wrong on detuning. Tuners currently add injection pressure and advance injection timing. Both good for MPG unless you drive around with your foot on the floor. I just added a Quadzilla XZT to mine last weekend and the results were very impressive but I wont post them until I can get a second long trip in with it as I had a 40 kmh tailwind perfectly behind me on that trip as well. If I posted my last trip results people would say that it was impossible. I keep all my fuel records in my gallery for comparison, I have been doing slightly better with my 2007 than your 2003 but it could be a difference in configuration.

 

25mpg i want a piece of that

 

Aftermarket exaust and intake. Throw in a hotter thermostat, smaller gear ratio, and of course, a custom tune to decrease fueling and advance injection timing under 2000 RPM to increase mileage!

 

How are you folks calculating MPG?

My method has been topping of with Diesel to the brim and resetting the odometer, and then calculating the miles driven by the number of gallons that it take to top her off to the brim again.

I frequently make 325 mile trips on my 03 six-oh FX4 with 56k miles on a bone stock engine, and I calculate 18 MPG with an average speed of ~65 MPH with about 900 # of stuff carrying around.
I used to have a Snug Top bed cover, and I tried dropping the tail gate as well, and I know have a Leer shell ,for when I carry my two Lab's around, and I still get 16-18 MPG range.

If anyone is achieving >20 MPG, I'm all ears!

 

I hear rumors of these 25mpg trucks but I'd chalk that up to math errors or rounding up... there is a 7.3 running around with documentation to back it up and he is in the 25-26 range but he has spent lots of time and money to get there but it wouldn't tow very well and he has put very high gears in it....

I would love for someone to show documentation of any stock diesel truck averaging above 20mpg city and highway driving...

 

I get about 12-14 MPG while pulling my Weekend Warrior stuffed to the roof at around 13k # and averaging...uhm 65 MPH on mix flat and 7% grades.

Eventhough it take a long time to fill her up to the brim, especially with high flow rate truck -ype pumps, I have'nt thought of a better way to calculate MPG.

 

Regarding the thermostat change to run hotter I am reluctant to change it as some of the 6L's have coolant issues such as puking, hot spots and some poor coolant circulation. Mine does not puke or loose coolant but I occasionally smell coolant in my vents which I am still working on tracking the casue.

In BC we are in rocky mountain terrain and so I recognize it effects our MPG. However I hunt and fish alot and in particular twice each year. My 18 buddies and I do a 8 day hunt or fish trips and travel 1000's of miles in 6 turbo deisels (ford, chevy and Dodge). In general all the older generation of trucks empty are getting 22MPG (1998-2000) and while the newer generation (2003 - 2007) are getting approx 18MPG in the mountains. The older gneration ups their MPG to 25 in flat areas on our Alberta trips but the newer trucks tend to have no real change. This is hand calculated. This is also verifified when we tally up the shared fuel bill at each trip. It is also obvious as the newer trucks are filling up 100 miles sooner than the older generation trucks.

I recognize that we may never recover the same MPG as the older trucks have less GCVW and higher compression ratios but I would like to try to get what deisels were known for.

I have a superchips 1704A tuner, disconnected EGR, gauges, synthetic fluids and etc and the superchips tuner on its economy setting basicaly gives me more power for equal MPG than stock mode while maintaing similar EGT and driveability. I am considering selling the superchips tuner for an SCT as it appears to have more flexibility for custom tunes. I am assuming the SCT has a custum tune that has advanced timing, reduced injection presure and defueling for the ultimate maximum MPG for 6L's. Can anyone tell me what MPG they are getting on such a mileage miser type tune. I am wondering is the mileage tune on the SCT or others any better than my superchip economy tune. I am getting about 14MPG city and 18MPG highway on ecomomy mode adn the same stock but with more power and better response.

 

The fuel in Oregon must be the problem... My dad has a 97 powerstroke and can get 22 when empty and on the highway but he still won't average 20!!!! I got 22 mpg in my 03 6.0 one tank but that doesn't make it average in the 20's. I would agree that the old diesels the ones without turbos can consistently get in the 20's...

 

I haven't custom tuned yet.. But before my lift on stock height.. I was getting 12 to 12.8mpg.. After installing my SCT Livewire and running the Performance tune that came with it.. I went up to 14.8-15.5mpg.. That is with some hotroddin times.. If I drove it on a full tank like a normal person... Could prob hit 16-17.. I do a lot of City/Hwy as well.. Stop and Go traffic.. etc..

 

I recently detuned my truck back to stock from economy mode and am getting .5 mpg better. I'm gonna leave it here with no egr.

 

Matt is currently (think he has it written already) working on an ultra economy tune. He is not going to de tune the truck, but he is going after every way to safely make MPG better. Actually making the tuner discipline the driver, not the other way around. This is the beauty of the SCT, everything is controlable, including pedel postion output. I like HP and TQ like everyone else, but I would like to see a way around all the BS (particulate filters, ULSD, everything but addressing the conservation aspect) to actually make a difference. Make every 6.0 powered truck on the market get (or have the chance to) 3-5 MPG better, then you have done something at easing the price and emissions hand in hand.

 

I heard the pre flash 03s had power and 20 mpg milage.
It would be nice to have that tune available.

I

 

I couldn't agree more. Better milage = less fuel burned = less emisions.

 

Thank you GPW, I wish everyone saw how simple this was.