2012, 4wd, 35" tires x 12", mega cab, 30k miles, full delete, #5 timing, and highest hp level. Can't get above 15mpg. I've heard of guys with similar setups getting close to 20mpg. I'm Going to call h&s, just seeing if anyone else ran into this, or if the transmission tune increased mileage any? The version on our h&s is......SW-1.03.1 / TV-6.8.47
Mild W/turbo.

Maybe I need dif version? Is it just an update, or do I get it sent to me? Thanks!

 

Oversize wide tires suck down mileage.

If you go tall, go skinny.

Drive 65, not 75 & mileage will really improve. sweet spot on my 6.7 with 4:10 gears is 65 mph. it really runs better there than 55.

Good luck !

 

Following

 

Yeah, I know the wide tires suck. But I know 3 guys with same year trucks and tire size that get 3-5mpg better than I get. Also have noticed that I get 1.5mpg better if I'm going 80mph vs 65-70

Just curious if maybe new intake, or version of software on h&s, or tranny tune would help increase?

 

The tires aren't helping but you don't say what gears you have or if you have an automatic truck, the G56 has a lower gear final output than the 68RFE does. As you are asking about the "transmission tune" I might assume you have an auto... the transmission tune helps a lot it smooths out the whole transmission and ensures the transmission is not shifting around all over the place. I ran mine without the TT for a few days as the activation code ended up in my junk mail, in that time I thought there was something wrong with the transmission as it was all over the place. From the beginning I used H&S intake manifold and also their boost tube which is also larger, I tried the turbo tuning but found it would spool too quickly and reach my boost pressure defuel point so now I run W/O Turbo and NO Timing. The lower the tire pressure and the stickier the tire will reduce fuel economy as well. I can't speak for MPG because I'm usually towing something when I use my truck but on long hauls I try to keep RPM around 1700-1750 on the hiway, max torque is 1650rpm.

 

i have logged 7600 miles with no load behind me (deleted, 3.73 gearing, auto trans). my total running average for those miles is 15.7 actual, real world, hand calculated MPG. the only way i will get over 17 is if i drive 65mph or less, all highway, and not much wind. if i drive 75mph down the interstate, i wont get over 16 no matter what.