How Does This Happen?

[Fleeingpepper]

My dad's truck is a 2500 with a utility bed and a tommy lift on the back. It's got the 350 TBI. It weighs 6500 pounds with nothing in the bed and for most of the past tank there's been an air conditioner in the back of it. It got 11.7 mpg.
My 2 Door Hoe got 11.2 mpg, and it has the Vortec and weighs 5000 pounds, if that. I didn't punch it all that much, but shouldn't it get at least what the 2500 got?
And his truck has 100,000 more miles than the Tahoe. Does the TBI actually get much better mileage? Also he has 245 tires, and I've got 265s, but they shouldn't make that big of a difference. If his truck weighs a whole ton more than mine, I feel like I should get better mileage than him.

 

[dcZ71]

Yes you should get a little better under the same conditions but not much to be honest, he's got the lower gear probably 4:10's plus he's got 245s, hes gunna beat ya in the city mileage, you probably got 3:42's or 3:73's and a inch bigger tire. Whens the last time each truck had a tune up? Were y'all driving similar roads?

 

[Fleeingpepper]

Yeah his truck has the 3.73s and I got 3.42s. Kinda dumb it got the towing package and tranny cooler, but only 3.42s. He had one maybe two years ago, but not many miles. I'm pretty sure the Tahoe has had one in the past two years, but I've only had it for a little over a year so I'm not positive.

 

[dcZ71]

Yeah its the gearing, you can beat him on the highway though.

 

[Greg]

Gears is the big difference, but what could also be robbing your mileage is what gas station you buy from.

For instance - up here in SD, if I get fuel at the Exxon station, I will get about 1 mpg lower than buying fuel from the Conoco station. Same driving conditions.

Right now I have the Vortec 5700 with 3:73s and if I buy fuel from Conoco I average 14.9 mpg (City/Highway).

 

[dcZ71]

I usually buy shell v power. last tank was 13.2, mostly city. vortec 5.7 3:73's

 

[Fleeingpepper]

Oh I only buy from Phillips 66 that has no ethanol. I will never fill up anywhere with ethanol! I just get awful mileage..dang.

 

[dcZ71]

I don't much of a choice usually, hard as hell to find non ethanol gas anymore, a shame really.


I found a nice site if y'all are trying to locate nearby non-ethanol stations. www.pure-gas.org

 

[94_C/1500]

I've had an idea about removing the ethanol, but you would have to mix it with race gas to bring the octane back up.

I got the idea from the test that you can do to find the percentage of ethanol on fuel. For the test you mix a controled amount of gas with a controled amount water. The ethanol and water mix. So, you could reomove the water/ethanol after it mixed together. But you would need a way to put the octane back in it.

My GMC looses a little power and about 2 MPGs with E10. My Scrambler runs horrible on it.

 

[dcZ71]

Same for my brothers 4.3 it was about 2 mpg worse on e10. mines probably 1-1.5 worse.