Hermann
Site Donor 2023
I do. about 44 mpg with 91 E0, about 40 with E10
e15 over e10 fuel worth it??
- Thread starter earthbound
- Start date
Which would be correct if the 10% ethanol contributed nothing. But that isn't the case. So something strange is going on here.
If you do the math, E10 has about 3% less BTUs than E0.
this I can see, but not going from e10 to e15
Well, as I posted in that thread, a claim that one gets more than 10% greater fuel economy on E0 compared to E10 means that:
This vehicle goes further on 9 gallons of E0 than it does on 10 gallons of E10, which is composed of 9 gallons of E0 and 1 gallon of ethanol.
Doesn't compute.
The only way that would happen is if the engine is running pig rich on E10. OEM programming can be way too conservative and cautious in some cars. Running E10, the O2 sensor will read lean so it dumps fuel to compensate, usually over correcting. Aftermarket tuning can help a lot with some cars. Subarus especially, they ran really rich from the factory in the late 90s and early 2000s. They'd be at 12.5:1 AFR cruising down the highway. It's not uncommon for a tune to pick up 3-4 mpg just programming the ECU to not go full retard.
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Hermann
Site Donor 2023
In a week or so I will be filling up. We will see if it stays around 40 mpg with the E10 that is now in the tank. The next fill will be 91 oct E0. The truck just sounds happier and runs smoother. My grocery store rewards usually makes up the diff between the fuels.
I know it’s crazy so I just looked it up. We left Iowa on Friday with a full tank of E15. Drove 405 miles and got 22.7mpg. Filled the rest of the trip with E10 and have gotten 25.3 and 24.2 at higher speeds. For some reason as we drove south the speed of traffic increased. So I guess it’s closer to 2 than 3 but still it’s a 10% increase in fuel economy. After leaving Iowa I didn’t see any more E15 at the pumps either.
All my numbers are calculated with the Fuelly app not off the van EVIC.
Just my $0.02
I use it all the time, don't notice any change in mpg.
Hermann
Site Donor 2023
Just a question. In the winter blend season is E0 fuel still ethanol free. My foggy memory thought alcohol was/is an oxygenate that used to be in winter blend fuels.
The fuel mileage differences between E0 and E10/15 may be somewhat vehicle/engine dependent. The only non-carbureted vehicle I extensively used E0 in was a 2008 Silverado 4wd with 4.8 engine. I'd use all E0 for many consecutive fill ups then do the same with E10. In about 4 years of doing the same commute, I consistently did 16.5 mg with E0 and could not break 15.0 with E10. Smelled just like a 10% gain.
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