Fuel millage

[svcattle]

What kind of millage are you guys seeing out of your 6.5 I can not break 16 no matter what i do

[Dvldog8793]

Howdy
I have found that the best mileage is in relation "stuff" and RPM.
"stuff" = truck weight and aftermarket do-dads.
- smaller lighter truck with normal tires and no HUGE bumpers or hot rod add-ons will get better mileage.
- some add-ons can help with mileage...open exhaust and air path...ect
- RPM, if you keep the RPMs in the 1800-1900 range you will get the best mileage.
- having a real good fuel system is helpful. Meaning a strong pump and fresh injectors.
- weight and rolling resistance(tires and aero-dynamics) can be huge part of the equation.

My 1999(RIP) had a gear vendor overdrive and many hotrod items. it was a long box crew cab with big tires and probably about 700lbs of "extra" stuff on board. I think I could hit 18 if I kept it in that RPM range and drove REAL nice.

My daughters 1/2 suburban with no aftermarket work and driving like a normal person can routinely get 18-20. If you lightened up the load and had stock tires on it, possibly 22.

My 1984 6.2 non turbo full size van gets 20 easily and could probably get into 26 if I really tried. I have always wanted to put a 6.2 into a 1995 caprice(aero-dynamic) and gear it properly to see what it would get for mileage, I am betting in the 30s

So, IMHO, there is no real way to say what any given truck/driver combination will get....only a best guess as to what a trucks POTENTIAL would be under certain circumstances.

[svcattle]

Mine weighs 7500 gvw 15.5 to 16 is all it will do not sure the rear end ratio I'll attach a pic of 65 mph rpm

[Dvldog8793]

Most likely 4.11 gears
The 6.5 makes real good power in the 2100-2400rpm range but it drinks fuel to do that.
It is operating with the most efficiency in the 1700-1900 rpm range.
Try running an tank at that range and see what happens.

[svcattle]

Well I jumped the gone posting I looked back through my fuel records over 12 tanks i started at 16.35 mpg with a low of 14.49 mpg the first six tanks were over 16 then dropped to 15 I've now got full synthetic gear oil in the front and rear diff and the Trans transfer case still needs changed. My dually weighs 8500 and gets 16 to 16.5 as well I was hoping the 6.5 would return a little better mpg but o well