tristan21

The gear vendor sounds like another option but the cost (?) would take along time to recoop. Just drive it man. I know diesel is expensive now but you dont get the piece of mind that you can pull, four wheel, race and still get better fuel consumption than most of the gassers your racing (ricers exempt). N.Johnson was right on with the weight of the truck and the possibilities the cummins provide. I get an honest 17mpg average when I drive slow but thats not why I bought the truck. Even if I told the wife that .
I also have to question the validaty of the fuel quality when I travel all over the US with this truck and I get the same mileage (14-15 since I usually drive 8 miles per hour over the posted speed limit) wherever I fill up.
I have noticed a little improvement from the 265's to the 285's but I shoul've went bigger, so I trust that larger less agressive tires should help you eco-penny pinchers a little bit. But whatever you do dont make any purchase based on anyones "padded" mileage figures or on the recomendation of a four wheel parts salesman.

topless

I have an '05 with 315's, Edge, 4" exhaust, tighter converter, and K&N intake. In town I average 16, at 60 I can get 17+ at 75 I get 15-16. So I drive how I want. If you get much over 8 psi boost, fuel mileage reduction is significant.

Leon441

My truck only got 16.5 stock at 60mph 16 at 70.

I added a TST and could get 19 running 70. Could not run TST on 4/4 towing so I upgraded tranny for the fuel mileage concerns. Ok that's only part of the reason I also wanted to drive the other makes crazy.

Raspy

Thinking bigger tires will get better mileage is a trap. It may sound good on paper, but bigger and wider tires are a lot heavier, so they take more energy to spin up. Also, they have more wind resistance, and more rolling resistance. I put 315s on and corrected my speedo. My mileage went down 1-1.5 MPG. If you think taller tires are the answer you must be thinking the gearing is too low and that's not always the case. It's the overall work being done and engine RPM is only one factor. I think the greatest gains can be made by slowing down because wind resistance has a huge and exponentially bigger affect as speed goes up. That's the hardest thing to do! Around town, fast starts means low mileage.
With modifications, like injector honing, the computer can be fooled to think your mileage is better than it is. It is not really measuring the fuel used, it's measuring the time the injectors are open. If more fuel is going through the bigger holes you're getting more power but the computer "thinks" the flow is what it would normally be. Hand calculations with a correct speedo is the only way to really know.
Since everybody drives differently and in different places (city, highway, mountains, short trips, long trips, towing, fast starts, lots of passing, etc) it's hard to compare truck to truck.

Wetspirit


Wetspirit

tristan21

Wetspirit you are absolutly correct... Kinda. The right rpm range for these trucks optimum mileage "sweet spot" is in the 1800 rpm range. With the 265's I was turning around 2400 rpm at 75ish. That means bad mileage. I drive 75-80 all the time and when I added the 285 AT's it made a noticable difference in the amount or rpm I run at the same speeds. I have'nt, nnor do I ever plan to hand calculate any mileage on my truck so I cannot report any actual gains. I think that you are right though as I know that wind resistance is a serious factor and that is why I mentioned the gear vendor. Which all things being equal would definatly give a lower rpm range and equal a lower mpg if you are the type of person who drives these highway speeds. You wont probably see much if any improvement in the mileage around town as that is where your rolling resistence comes into play.

When I mentioned I should have went bigger I suppose that I should have clarified that meant that I would have preferred a larger tire but then again I could care less about the mpg.

reidry

Thinking along the wind resistance line. Has anyone tried lowering the truck 1 or 2 inches both front and rear? This would reduce the overall profile (viewed from the front) and get the airdam closer to the ground.

Ryan

nojodas67

what is rokketech???

MikeyB

It's a modified crankshaft sensor that adds two degrees of timing.

www.rokktech.com

MikeyB

nojodas67

I see...If I add a box like Edge or SixGun then it's not necessary to advance the timing manually, right?

On a different note: Am I correct to assume that a torque tube alone will do nothing for improving performance in a sense that an intake system is only as good as its most restrictive section. In that case, in order to see considerable gain in CFM's would I have to replace filter box, torque tube, intercooler tubes, intake manifold, intercooler? That could get very costly.

Duallydog

Now saying that 25mpg is pure bull **** may not be accurate. If you take a 2wd single cab or even a quad cab short bed, with a better running than average cummins, broke-in and a few diesel viagra's (enhancers), and good weather conditions should be able to make 25mpg. I am serious, if mine with duals and the Rock of Gebralter on the front (Holes cut in a few weeks ago now, not at the time), can make 21mpg doing 71-72mph then a stock front end, single rear wheel should be able to. Course I haven't had that kind of mileage since.

Argo

I jsut made the drive to and from the Cape on MA and SA, TX. On the way there with no load doing 80+ on the road I saw about 17 mpg. On the way back with 8500 lb trailer bumper pull, I got 9 mpg that is with hitting a bad snow storm in TN while between knoxville and nashville in the mtns. With a severe head wind...... I have 4.11 gears and 285s(bfg at/kos) That was not a fun haul by the way with the snow and what not. Followed a big rig for about 100 miles going SLOW. If any of you guys saw a silver dodge with a large power cat(boat-glacier bay) on the highway this weekend between SA/Dallas/little rock/memphis/nashville/knoxville/baltimore/nj/ny/MA. That was me.

Dorkweed

Just filled up today and checked mileage. This last tank got me 19.5mpg hand calculated. The overhead read 18.1mpg!!! This past tank was probably evenly split with empty highway miles, suburban towing miles and suburban empty miles. I had 620.4 miles on the tank when I filled her up; and yes I did fill her right to the neck now that I'm able after the fuel tank vent mod!!! I have found a local fuel station that whenever I fuel up there I seem to get really, really, really good mileage!!! The tank prior to that I averaged 18.7mpg!!! Just for the record, I have been accused of driving like a Grandma, but I still have my fun with my truck!!!!

abc4yew

Dorkweed, how empty was the tank when you refilled....what did your overhead miles to empty say. ks

goose2

Some of these mpg woes are the quality of the winter blend fuel. There are times I get better mpg at diff. stations. Man I can't wait for summer.

Dorkweed

The DTE was at 0 when the mileage on the tank read about 608-610. I drove another 10 maybe 12 miles further to the station to get to the 620.4 for the tank. I put in 31.8xx gallons. I fill till I see fuel in the filler neck. It's a piece of cake now with the fuel tank vent mod!! Before the vent mod, I was only puttin in 28-29gal on average and getting about 525miles on a tank of fuel. I can't imagine driving that far past DTE 0 to put 37-38gal in like some say they do. Only thing I can figure is my float is a little off when compared to the others.