[Ecky]

Originally Posted by litesong

I have 10+ years of experience with 87 octane 10% ethanol blend (E10) vs. 87 octane ethanol-free gasoline (E0). My 5 low-compression ratio, 87 octane gasoline engines show a percentage MPG increase, E0/E10 of 8%, 8%, 7%-8%, 7%, & 5%. E10 advocates tote the energy difference between E0 & E10 of 3% as showing only 3% MPG gain for E0 over E10. However, the following is important:
87 octane 100% gasoline component (E0) is 87 octane. duh!
Reported in many websites, inaccurate but "designated" 87 octane 10% ethanol blend (E10) has a gasoline component that is 84 octane. Because of great quantities of "ethanol in gasoline industry" propaganda & lobbying to artificially lower E10 prices, American drivers have accepted 84 octane component gasoline to be used (not efficiently burned) in their 87 octane gasoline engines. But, 87 octane E0, as burned properly in an 87 octane, low compression ratio designed gasoline engine, has 8% to 5% better MPG than inaccurate, but "designated" 87 octane 10% ethanol blend, which has neither ethanol component or gasoline component that is 87 octane.
Now the "ethanol in gasoline industry" is pushing inaccurate, but "designated" 88 octane, 15% ethanol-blend (E15). Inaccurate, but "designated" 88 octane ethanol-blend E15 has a gasoline component with an octane of 83.5.
If the "ethanol in gasoline industry" can successfully market inaccurate, but "designated" 88 octane ethanol-blend E15, they will then push inaccurate, but "designated" 87 octane ethanol-blend E15, which has its gasoline component as 82.4 octane. In all cases, the ethanol blends have no fuel components that are 87 octane & all ethanol blends are inefficiently burned.
The magic & power of propaganda to get people to accept products in their lives which are not "efficient" is remarkable.
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Glad to see you live in Sequim. I live on the east side of the Salish Sea (Puget Sound). Do you buy your Ethanol-free E0 at Chimacum or Port Angeles? Sorry, you have to pay so much for E0. Its still expensive, but on the east side here, I get my E0 for $3.42.

Are you certain that's how it works?

To use a similar item as an analogy, you *can* in fact get the properties of a 5w30 oil by mixing a 5w20 and a 5w40. It isn't just two dissociated oils floating around in the crank case, they average out and you get the desired viscosity.

Gasoline itself is a mixture of a lot of different compounds anyway.

Taken from Wikipedia:

The octane rating of gasoline is measured in a test engine and is defined by comparison with the mixture of 2,2,4-trimethylpentane (iso-octane) and heptane that would have the same anti-knocking capacity as the fuel under test: the percentage, by volume, of 2,2,4-trimethylpentane in that mixture is the octane number of the fuel. For example, gasoline with the same knocking characteristics as a mixture of 90% iso-octane and 10% heptane would have an octane rating of 90. A rating of 90 does not mean that the gasoline contains just iso-octane and heptane in these proportions but that it has the same detonation resistance properties (generally, gasoline sold for common use never consists solely of iso-octane and heptane; it is a mixture of many hydrocarbons and often other additives). Because some fuels are more knock-resistant than pure iso-octane, the definition has been extended to allow for octane numbers greater than 100.

Octane ratings are not indicators of the energy content of fuels. (See Effects below and Heat of combustion). They are only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced. Ethanol BTUs can be compared with gasoline BTUs in heat of combustion tables.

It is possible for a fuel to have a Research Octane Number (RON) more than 100, because iso-octane is not the most knock-resistant substance available. Racing fuels, avgas, LPG and alcohol fuels such as methanol may have octane ratings of 110 or significantly higher. Typical "octane booster" gasoline additives include MTBE, ETBE, isooctane and toluene. Lead in the form of tetraethyllead was once a common additive, but its use for fuels for road vehicles has been progressively phased-out worldwide, beginning in the 1970s