1FUNZ71

I run my tires at 40psi all the way around. Keep your windows up and run the vent instead of the A/C. During the summer, A/c on 5, who cares about MPG.

I was getting 19.5-21 with the volant and hooker. 23 is pretty common after the tune if I stay out of it. 3.42's with a 31.5 tire is a awesome MPG combo. This is with decent driving habits and alot of a/c use.

My buddys truck is up around 26MPG. Its an 03 GMC RCSB Z71 with 33's and 3.73's. I know he has shorties, wait4me tune, no cats, TB spacer, CAI, plugs, wires, and I think rockers as well.

sharno

wow mines an ecsb with 3.73 gears. but im not sure what im getting in mpg. but i get on it a LOT like everytime i take off LOL im addicted to it. but on the trip i will def cut back on that. well thanks for the reply.

CHEVY6000VHO

iTrader: (2)

Justin, DO NOT leave your tailgate down. Rice University did an aerodynamics study of this and found that you create more in bed turbulence with the tailgate down.
As they found that leaving it up actually creates a sort of wall or bed of air that keeps the air moving from top of cab to top of bed caps and over the top of the tailgate.
I guess with the tailgate up it creates a wind wall in the bed. I don't really know how to explain as I see how this can work in my head, but just can't relate it to words.
LOL, anyways keep the tailgates up if you want better miliage. Believe it or not.
Also, do what TXSilverado mentioned above as well and you will be at your best possible MPG average for your trip. I too notice 70 MPH is max for good gas miliage(19 MPG) and 65 MPH will give you Great MPG #'s(21-22 MPG). That's with my ECSB 6.0L LQ9 truck. These are also straight up highway numbers with no A/C. With A/C will take away 1-3 MPG depending on speed.

Jim

CHEVY6000VHO

iTrader: (2)

My buddys truck is up around 26MPG. Its an 03 GMC RCSB Z71 with 33's and 3.73's. I know he has shorties, wait4me tune, no cats, TB spacer, CAI, plugs, wires, and I think rockers as well.[/QUOTE]
I don't believe it. Not with that combo.
It's not even your truck.
Don't believe everything your "buddy's" tell you either.
Hey............., I can fly!!

Jim

TravisH

iTrader: (1)

adding acetone has been giving guys 1-5 mpg...run a search on it, i think it is 4 oz to 10 gal.

1FUNZ71

I don't believe it. Not with that combo.
It's not even your truck.
Don't believe everything your "buddy's" tell you either.
Hey............., I can fly!!

Jim[/QUOTE]


Well, I do believe it, I have found the DIC MPG to be pretty close to what it is on paper (usaully off 1-2mpg). Wether or not if you believe dosent change the fact of thats what he is getting on the hwy. I thought he was full of too. My 04' RCSB 2wd didnt get that good of mileage. I have driven it and seen it with my own 2 eyes. Like I said what you believe has no bearing on the facts.

Oh.......I can fly.

Mr. Sandog

The most critical number in the whole equation is engine RPM. If you keep engine RPM right around 1800 RPM or a little lower, you will achieve maximum efficiency for the LS1-derived motor. As soon as you start creeping above 1900-2000 RPM and higher, your mileage starts to take a dive.

You can have all of the other things in place (lean tune, free-flowing exhaust and intake, etc.) but if you are running 2400 RPM on the freeway, even with the cruise control on, you will be leaving mileage on the table. That's just how LS1-derived motors operate.

I found this out when going from 3.73 gears to 4.10 gears. Everything else remained exactly the same, and I lost 2+ MPG on the freeway. Why? Because my crusing speed on the freeway (70 MPH), went from 2000 RPM with 3.73's (the absolute outside of motor efficiency) to 2200 RPM.

That change was going from a .70 overdrive, 3.73 gears, and 32" tires on a 6,000 lb truck, to 4.10's. I went from 19.7 MPG to 17.3 MPG, and the only thing I changed was gears. I didn't even have a good tune, just the stock Radix Superchips tune, which is fairly rich.

If I can get 19.7 MPG at 2000 RPM with a supercharged, 3-ton brick, I bet that 22-23 MPG or perhaps more is available for someone running 1700-1800 RPM in a vehicle that weighs less and is properly tuned.

onefastz71

I've got an 03 ex cab short box 5.3 with 3.73 and 33 and the last to nights on the freeway i've got between 13 to 14.5 I don't beleive he is getting 26 either unless he has gears or something else.

1FUNZ71

Thats what the truck gets. Believe it or not. I wish I got that kind of mileage. Just because I dont see that kind of mileage in my truck dosent mean I dont think it is possible. That is all I have to say about this. If you don't want to believe me, hey fine with me, just thought I would add my .02.

Dans Denali

Blow up the tires to the max sidewall pressure, use 5w30 oil, new air filter, slow down, I get 16mpg at 70 and 18mpg at 60.

Dan