Suggestions?

Have an 06 CTD Quad Cab 4x4 6Speed big horn, 11.5 axle completely stock, just hit 2500 miles, got 15.6 hand calculated MPG last tank with city/highway combination no payload, on drews brew. Made a 600 mile trip to Houston day after delivery with a 16ft trailer with aproximately 1200lbs payload and got 12.6 MPG. (70-75MPH all the way, no brew) It seems as mileage is slightly improving with break-in but am very dis-satisifed that a truck with 6 gears is turning 2300RPM at the speed limit. (70MPH) And trip PC only shows 14.5 at highway speed unloaded on the brew. What the heck was Dodge thinking? I get better mileage in stop and go traffic if I keep the foot out of it. 2nd is a little low for start off unless you're towing, 3rd-6th is very nicely geared, especially if towing, just need a 7th!! Dare I mention a Duramax on this form but our '06 chevy brush fire truck at work gets 17-18MPG with 4000lbs of water and equipment on the back with some pretty abusive driving. Otherwise I love this truck, I'd much rather push a goat than drive a duramax hence why I bought one, any suggestions for less RPM or better mileage? Thanks!!

 

What rear axle ratio ?

 

I have a 373 ltd slip 6sp and the hemi in my 2500, at 60 mph in 6th I'm right at 2000 Rpm, so I don't thing your that far off.

Your mileage will improve...

 

My guess he's got the 4:10 rearend - which is what I have and found to have poorer mileage than my '04 with the 3:73's...

Maltese - if indeed you have the lower rear end, then you might consider what I did...put larger diameter tires on it to compensate so it isn't turning such high RPMs at 70 mph. (but I had to lift it to do so...maybe go for something a little smaller than 35's so you can just add the level kit to the front) Also, although it might not be as successful with the 6-speed, the reflash that is out there now for the '06's made nearly a 2 mpg positive change in my mpg - if you haven't gotten that yet I'd look into it also...

 

Pretty sure I have the 4.10 rears, will double check on that. The re-flash you mentioned, is that a programming option, and if so is it a dodge/cummins dealer deal or are you talking an aftermarket program? I hadn't thought about bigger tires and wheels improving mileage, makes sense though, did you realize a notable difference?

 

I'll do a copy paste from the fuel mileage thread. . .youve got 3.73's BTW

 

What the heck is an 11.5" axle? Is that the diameter of the ring gear in the diff?? I wish DC would just give us something anyone can understand like 3.73 or 4.10. I got the same truck as Maltese, except automatic and about 250 miles on the clock. I'm getting high 17's but I have been babying it.

 

that is just the size of the pumpkin.

the 1500's have 9.25's the 2/3500's have 11.5's in the back and 9.25's in the front for 4x4's.

 

How big of a deal is an overdrive gear set, and aproximate cost? And is it your opinion that my mileage will improve to near what your getting in the 18's? If so, perhaps I should just grin and bear it for awhile.[:@]

 

Drew....So 11.5" = 3.73 and 10.5" = 4.10, correct?