Think it'd be that much different if u had a 6L / 370? How much weight how u pushing in that beast? I know you're way more than my lil RC.

That's horrendous.

Not sure who does your tuning, but u might wanna get someone else to do it. A lot of guys like Blackbear & Wheatley.

 

Mine weighs 6400lbs with me in it and a full tank of gas...

 

Best mileage I could get in my 2wd crew 5.3 is 18 Highway and it even has the shitty 3.23 gears. Why 3.23's GM? WHY? City driving is always 16. My rcsb with the lq9-t56 will easily get 15mpg city, never checked it on a road trip.

 

My fueling is dead on, wideband verified. Thanks for the advice though. Put a cam and 3600 stall in a 2500 HD and let me know what gas mileage they get. They barely get 11 mpg stock, although they are weighing about 1k more.

 

I never said I had a 22-gallon tank...I have a 26 gallon tank; I just choose to fill it up one tick mark before "E". As long as you are consistent with your fill-up point, you do not have to run it dry to get accurate manual MPG calculations. You won't see this guy sitting on the side of road out of gas. A friend of mine who works as a mechanic at the local GM dealer told me that running the tank almost completely dry is hard on the fuel pumps, too.

 

interstate driving 70-75mph i am getting 18.7mpg
highway 55-65mph i am getting around 17.6mpg
average now being 16.8mpg

it was 13.8mpg

 

Gotcha. If I owned a 2500HD, I would be a dipshit to put a 3600 stall & cam in. I'd buy that vehicle as a workhorse & a lighter truck as my bullet.

It's not a bad idea to stay under the fill mark & not overfill, cause it can to lead problems from what I've heard on here. You're correct, it's also a bad idea to run til near empty, it's hard on fuel pump, since being submerged cools it.

Currently, my MPG is terrible. Maybe it's due to my stall, cam, I now it's cold here; needs a re-tune I'd think. I have an Evap /Fuel issue, & haven't checked my codes recently. It's gotta be in the 10-13 city range.

 

do ya'll think the 3.42 gears are hurting or helping the fuel mileage?
i have a set of 3.73's i could get installed if it would help out...

i'm just wondering because of it being a crew cab and with 24x10 wheels and 32.5" tires if the 3.42's are makin the truck lug alittle... i am at around 1800ish@70mph and 1850ish@75mph

help me out with some thoughts

 

Well I can tell you my experience going from 3.73s and 35s to 4.56s and 35s.....with the 3.73s, my gas mileage had a bigger range, it would b e something like at worst 8 and at best 18. with the 4.56s it had a smaller range but the average was about the same, it would be something 10 to 16. In both cases the average is 13, but the local values are different.

 

hmmm...

anyone else have more thought?