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Old 10-01-2017, 06:47 AM   #8
RCF
 
Drives: '17 2SS, NGM, MRC, DPP; '19 F150
Join Date: Apr 2017
Location: Katy (Houston), TX
Posts: 442
Quote:
Originally Posted by JohnE View Post
I expected the E85 to be about 70% as efficient as regular gasoline. So far, I have averaged 17.2 MPG on E85 which would imply an efficiency ratio of 17.2 / 20.5 = 83.9%. I'm going to be conservative and call it 80%.
Just to clarify some info on ethanol vs e85 vs gasoline...

Pure ethanol has about 30% less energy content per gallon than pure gasoline. Gasoline today (99+%) already has 10% ethanol in it. So E85 (if it's truly 85%, most likely it's somewhat less) would have 75% higher ethanol content than gasoline. 75% x 30% = 22.5% lower energy content for E85 vs gasoline.

Have you checked the actual ethanol content? Theoretically E64 would give you approx 84% of gasoline's MPG (what you're seeing). Knowing your actual ethanol content would be nice to see where you are vs theoretical.
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