Mileage

It's really not that ridicules. I've a 5.7 liter with 3.42:1 gears and am lucky to get 14.5 to 15.0 mpg. Tow anything or run a little hard and that drops quickly to 12.5 to 13.0 mpg.

And big block Chevy's have never gotten anything that could be called good mileage.

Brian

Ya got that right, I know first hand. Time to down shift with the trailer on when attacking a hill.

Brian

It's not really that ridiculous. It's the high numerical rear end and the overall weight of your truck that's the culprit. Have you taken a look at the frame on that thing? There's a lot of steel in that truck, plus I'm sure with it being a 4x4 the tires aren't exactly the type you'd want for the least rolling resistance.

Is it 366 cu. in? I thought it was a 383 - maybe I was wrong.

Cheers - Jonathan

the 6.0l is a 364ci

a 383 would be a 6.3l (6.27 to be exact)

the 4.8 is a 293ci the 5.3 is a 325ci the 8.1 is a 496ci

Liters are typically rounded...the 5.3 is a 327ci and the 6.0 is a 366. if I remember right, the terribly missed 350 was closer to 348ci. Try to get the exact ci-L conversion for the 350, 400, etc...close is the best it will get! Trying to get exact with the liter to ci conversion is pointless. Kind of like a 1000cc Motorcycle engine could be a 989cc or a 1004cc or anywhere around there.

umm... shades.. buddy... those ci displacements were taken directly from GM powertrain's website. That's why I gave the link.

-Bret

and the 350 is 349.85 CI...

Well I think Bret is right about the figures and Shades is right about the rounding off aspect, "6 Liter" does actually equal 366 ci. The problem is the engine is really 5.967 Liters according to the '05 literature I have.ie, bore=101.6mm,(the old 4"bore) and the stroke is 92mm(3.622")...364ci Brian O.

Dude, I stand corrected! I had heard different from GM Dealers...my fault for believing them huh?

Same result but different equation that I have used for YEARS...Its the same one I have found to be used by some of the best engine builders. I had to dig to find the equation that's why I didn't have it last post and was a bit off with my memory...4"(cyl bore)x4"(cyl bore)x3.48"(stroke)x6.2832(.7854x # of cyl's)=349.848576ci

I have an '04 Silverado 2500HD with the same motor and gears and am getting around 10-11mpg in town and 12-13 on the highway.

My buddy has an '05 Chevy with the 6.0L and 4:10 gears. He is getting right at

When he straps his 8,000 lb. boat with trailer to it, he gets lot less mpg. But since he spent $50K plus on the boat and $40K on the truck, the gas mileage is the least expensive part of the equation.

Mark "Those who live by the sword get shot by those who don't"

I also have the same truck.The engine is 366c.i. and the tires are

Let it break in a bit.My truck only has 6,000 miles on it.Same truck as you,and last tank was 12.47