So with ethanol, we have higher octane?

[MrWideTires]

I keep hearing that with ethanol, 93 octane is not really 93... it's actually higher, and the same with other fuel grades. Is this true?? Because my SpecV uses premium.. if this is true I'll start using 89, at least during the winter.

 

[MNgopher]

No, just because fuel has ethanol does not make it higher octane.

Ethanol alone has a high octane rating. E85 is 100+ octane.

When blending with gasoline, the blenders take into account the high octane rating of ethanol. An 87 octane E10 (10 ethanol blend) is actually a blend of ethanol and 85 octane gasoline. the net result is an 87 octane fuel.

Same goes for a 93 octane premium E10 blend. Usually a 91 octane gasoline with 10% ethanol. Nets result is a 93 octane fuel.

 

[Bill in Utah]

And remember for most vehicles, you will get worst MPG with a ethanol blend fuel.

Bill

 

[NYSteve]

Higher octane with less energy per gallon. This means it does resist detonation better but provides less over all energy.

 

[mechtech2]

With pump gas, the octane rating is the octane rating.
How they get there is another story. The end result is the end result.

If we are talking about PURE alcohol, like we use in the wheelstander, then the high octane is important.