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Old 08-01-2012, 09:23 AM   #421
Napalm
Focus Enthusiast
 
Join Date: Mar 2011
Fan#: 83922
Location: Memphis, TN
What I Drive: 2012 Focus hatch

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That bit about higher octane fuel not having ethanol is a half truth.

Some refineries don't put ethanol in their 93 octane test blend, some do.

Irony: Ethanol actually raises the effective knock rating (it burns cooler thus it cools the chamber thus reducing the chance for knock)

So technically you can advance the timing quite a bit with an ethanol blend.

OH and get this - typically on a BTU/gram or specific heat calculation - 87 octane would have more energy than 93 octane. But because of that - it increases knock events thus leading to de-tuning to protect the engine. but only when Comparing pure gasoline to pure gasoline. Adding ethanol to both mixes reduces the total BTU/gram.

Which is why you get more power out of 93 octane. its one of those balancing events.

but remember those Alcohol funny cars. If you pack enough in, and you increase your compression ration, and you increase your spark energy, ethanol will make some impressive power. but you need gallons upon gallons of it.

but hey its green right? regardless that it takes more energy to make than it produces.

Its still green right?

sorry I might get ranty in a bit.
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