Increase my MPG (recommendation needed)

[shelbytt]

Guy's

I have a 2004 Duramax GMC 2500 SLT 4x4 and LOVE it, this is my 1st Diesel. It is the LLY engine and so for pretty Happy. I have added some 285 75x16 Inch Tires and it knocked my Gas Mileage down a lil. Right now Im getting approx 16mpg and have about 5k miles on it. Im waiting for the JUICE to be released for my LLY, but in the mean time I'm looking for recommendations that I can do right off the bat to tweak a few more MPG out of it. From what I have read it looks like replacing the AIR BOX & Exhaust will help some, my question is what it the BEST recommended Air Box and Exhaust to go with and if any other suggestions send them my way.. If you have a place that you have seen the best prices let me know. :confused: THX Shelby

[mdadgar]

I'd take 16mpg and be happy with it. My '02 gets 14mpg combined around town and stuff. 16 on the highway. Maybe.

10.5 towing my 8K lbs trailer, which actually seems in line with everyone else.

My empty mileage seems low, though.

- Mark

[mark45678]

There isnt any mods I know of it add MPG.... keep your speed to around 70 mph and you should see close to 18.5 mpg... all the power mods that have added fuel timeing will help slightly but the extra power gets used alot more then I care to admit!

[shelbytt]

Mark, You might wanna read some reports on what some guy's out here have Posted once they added The Juice. From what I read they were reportsing MPG in the low to mid 20's

[mdadgar]

Shelby, I've seen a bunch of those posts.

I've also seen a bunch of posts from guys with trucks just like mine that get 18mpg at 70mph with a stock truck.

Hmmm.

I sure as hell don't get that.

- Mark

[MIKE WIENER]

MPG Will go up as your motor racks up a few more miles. it is still verry tight at 5K. At 10 to 15 K you should be able to better juge. Those new tires are they taller then stock. Spedo. may need recalabrating.

MIKE WIENER

[Jon Wolfe]

When I'm a conservative driver, my 2004 LLY 2500 HD unloaded and with the tailgate up gets 19-20 mpg on the highway. I bought the truck new and immediately took a 3 hour trip and got 19.8 mpg of the lot.

Around town I get 16 and towing a 7000 lb. TT, I get about 14 on the highway and relatively flat terrain.

Needless to say, I have been very pleased with the fuel economy, and everything else on my Chevy. I'm using Delo 15w-40 and everything is stock except for a K&N air filter.

smile.gif

[Craig C.]

If you haven't already done it , change all fluids to a good synthetic such as amsoil!! I'm running 15w-40 HD diesel , 2000 series 75w-90 in the diffs , and amsoil atf in the transfer , haven't even changed the allison fluid to their torque-shift synthetic yet(got it today) and have gained 2 1/2 MPG!!!!!!good luck , also waiting for the LLY juice!!!!

[mdadgar]

Sorry, but no way, no how did you gain 2.5 mpg from switching to synthetics oils.

Synthetics are good, but not that good.

What's more likely is that your truck is breaking in.

- Mark

[HDMXDiesel0817]

You want better mileage, put your stock tires back on you'll get mid 20s, as long as you keep your foot out of it and hang around the limit, 65. Is your Bed covered with something? Hard tonnou? Cap? If not is your tailgate down? Honestly does the tailgate down make any difference in mileage (sure it may increase drag, but still)

I'm getting mid to high teens with my 285s and it doesn't bother me that much. That's in the 70-75 mph range. Not running any tunes yet on my quad, but will as soon as my tranny is upgraded in a couple weeks.

I'd like to see a 2.5 mpg increase with all synthetics...but that's somewhat hard to swallow. What else did you do that you aren't telling anyone ;) haha!

[Marty Lau]

I be confused. :confused: A guy buys a $45,000+ monstor truck big enough to haul a Honda in the bed, put 6 people in and with the ablity to Tow a house and he puts huge tires that increase rolling resistance and wind drag and he gripes cause his MPG is ONLY 33% better than a 8.1 gaser. :confused:
If you want better MPG.....slow down, get standard tires back on, cover the bed and break it in as soon as posible. If you really wanted good MPG from DuraBux ya should have got a 2500 2X4 straight cab, 6 speed. It kind of reminds me of the guys who buy a jet boat to run on the Missouri river they will buy a $25,000+ boat to play with but they roar up the river and drift down because they can't afford the fuel for their toy boat. :eek:

Don't want to get too grouchy I'm just tired of hearing people gripe about situations they put themselves in.

[ 05-26-2004, 01:19 PM: Message edited by: 16ga SxS ]

[shelbytt]

1st of ALL not %itching at ALL if you would have read my original POST. I Simply asked suggestions, and a few guy's were able to send me suggestions that I think will Help. Im VERY happy with the 17-18mph that Im getting I was just curious about tweaking it a lil more since I ready some guys claiming they get 20mpg wityh the JUICE. If you don't wanna be grouchy and your next time just bypass the MESSAGE.

Just read the entire POST b4 you blabber off.

[ynot]

Read something cool on Consumer Reports in '97. The new design of trucks with the taller rounded hoods, tapered nose to tail, etc. made the tailgate down thing obsolete. Put something light in the bed and drive down the road and it gets sucked out by vaccuum in the bed (i.e. negative pressure). Supposed to be designed that way so mileage is maximized with the tail gate up, and of course aids in unloading groceries when you get home (less trips with half your stuff in the street in front of the store). Also, the main thing that fueling boxes do to mileage is to confuse the trip/ mileage counter. The only accurate test is gallons/ miles, even with just tall tires. No trucks compare fuel in/ fuel returned. It's all fuel delivery, which is no longer accurate with a box, as the OEM computer doesn't know that the added box (and fuel) are even there, and has also actually shown the OBDII to relearn your driving, as it "thinks" you slowed down your driving habits (ya' right ;). My old truck showed 24mpg bobtail, but actually averaged 16.7 consistantly. Ran hard tho...T