3.42s or 3.73s?

 

3.73s, they came with the Max Tow pkg. Far as I'm concerned, gears are the number one ticket to acceleration, and with a 6 sp trans that has two overdrives it was an easy choice to go for the 3.73s.

I used to have a '76 Suburban with a built 400 smallblock, TH350 and 4.11s. It was a beast, but listening to the Flowmasters at 3500 rpm on the freeway got old. I finally had a 700R4 built to take the power ... man what a difference. The lower first gear was nice, too.

 

I have 3.73s and 285s too, but your mileage seems better than mine. Though it was the tires plus the gear. Hmmm. I got tuned by BlackBear yesterday and I'll have a tonneau cover on within the next week, and I'll be happy if I can set the cruise to 78 and average 16+ during our upcoming vacation.

 

Wow, that's really good. E85 usually kills mileage. I don't even think I can get this figure down hill, with a back wind.

 

cruise set at 72 mph {gps indicated}. coming out of chicago to des moines on sunday. then got to missouri. hills killed the mpg.

i run a **** ton of timing in the truck on e85, hence the mpg fun.

 

It all depends on what quality of gas and tune you have as with any motor. My 2010 CCSB 6.2 z71 with 3.42s gets 16.5-16.8 after a tank of mixed driving on 87 octane. Mixed driving for me is about 50 hwy miles and 25 miles of gravel roads and pipeline right aways per day. We're talking 1-2 gear only, creeping along the roughest roads you can imagine.

Here's my breakdown

87 octane - 18 hwy, 16.5 mixed, 13 city

91 octane - 20.5 hwy, 17.3 mixed, 14 city

Now my tuner has set my fuel tables up awesome. We've spent a lot of time doing nothing but fuel and timing tables. I'm also running a metric F ton of timing on 91 octane, which helps a lot.

 

Brand new numbers! Went 100 miles, spent half a tank on the guage (which happened to be 9.4 gallons???), and ended up with 10.6 MPG. This report was 90 percent city.

 

I would run my truck into a pole seriously 100 miles for half a tank? I've been getting 310 a tank all city, but just put 456 gears in, and I'm getting 2mpg better so far.

 

If you pay attention, it wasn't really half of the tank, it was 9.4 gallons. At that rate he would get 275 miles on a tank, which isn't that much lower than 310.

 

I wonder if the guage is off, or if my tank is only 20 gallons or so. Anyone with a sierra snap a picture of their fuel tank?