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Hello to all. Let me start with this is my second Sierra Denali. My first was a 2017 Denali Ultimate. 6.2 with all the bells and whistles. Pearl white, black interior and the brembo brake option. I did the cold air intake and a cat back. Well, Aug 29 while the wife and I were heading out to someplace to hike. Someone running from the cops ran a light and mailed the truck in the right side right in front of the rear tire. Totaled the truck. $25k in damages.
Anyways. Back to the op. With that 17 i would regularly see 17-24mpg. In Montana. This would include around town and highway driving. On the longer road trips i could hit 26mpg.
I now have a completely stock 2018 Sierra Denali Ultimate. Identical to the 2017. Even with the Brembo brakes.
So. I am doing an experiment. I want to see what really can boost the mpgs of these trucks. So for 5,000 miles i have driven the truck trying to maximize it. My typical drive is up and down I65 in Tn with speeds of 70-80 along with driving from Columbia to Lawrenceburg with speeds fluctuating from 50-70. I've gotten it to 20.1mpgs and it's pretty much stalled there. So today i put a cold air intake on it and I'm gonna drive it the same way till the fuel mileage gets to a point of where it stalls and I've done at least 5,000 miles. At that point I'll put a cat back on it to see what happens then. Just an experiment I thought i would share with yall.
It doesn't make that big of difference at all. The factory calibration already targets 14.1 for the stoich ratio knowing that everything is basically E10. Even if you ran E0 fuel, the stoich ratio of 14.1 is still what the o2 sensors will try to achieve.
Greater than 10% and then fuel mileage can start to suffer. I get an easy 2-3mpg less on the freeway when I run E70 from the local station compared to E10 89 octane.
Yes the ecu will adjust to keep afr's where it needs to be, however when it comes to ethanol in fuels; it takes more to get the same energy as non ethanol fuels.
Right I know, I'm just saying that the 5-10% that you do find in your 91 or 93 octane is not making a big enough difference because the computer already takes that into account. Getting well over 20mpg on the freeway is no problem for me with E10 89 octane, I would basically get the exact same mileage if I spent a lot more money for E0 91 octane. So it's not worth it to me.
I had a 2000 ws6 6 speed car back before they stared adding ethanol to the fuel. It would consistently get 27-28mpgs on the highway. When the 10% ethanol was added; the fuel mileage dropped to about 22-24mpgs. It would also pop the cel for lean conditions every couple weeks.
10-30-2021, 09:05 PM
Fuel mileage and 6.2 fun.
