# Ethanol blended gasoline



## Greg200SE-R (Feb 5, 2003)

Here in Hawaii, we are expecting to have all of our gas become E10 by summer 2006. E10 is a blend of 10% ethanol and 90% gasoline. An article in our newspaper makes it sound like such a great thing, saying that ethanol wil make our gas cleaner-burning, cheaper and will even raise the octane rating of the blend (slightly). They go on to insinuate that pure ethanol would have an octane rating of 113. 

Our best gas is 91 octane, and if my math serves me correctly, then 10% of 113 plus 90% of 91-octane would bring the blend up to around 93 octane. This sounds nice... But, how would this compare to "pure" 93-oct gas? 

From a purely performance standpoint - what, if any, bad effects would ethanol blend have on our vehicles? I know nothing about ethanol and I tend to get little apprehensive when the media has nothing but good things to say about it. What do you guys think? Thanks.


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## captain_shrapnel (Sep 10, 2004)

Greg200SE-R said:


> Here in Hawaii, we are expecting to have all of our gas become E10 by summer 2006. E10 is a blend of 10% ethanol and 90% gasoline. An article in our newspaper makes it sound like such a great thing, saying that ethanol wil make our gas cleaner-burning, cheaper and will even raise the octane rating of the blend (slightly). They go on to insinuate that pure ethanol would have an octane rating of 113.
> 
> Our best gas is 91 octane, and if my math serves me correctly, then 10% of 113 plus 90% of 91-octane would bring the blend up to around 93 octane. This sounds nice... But, how would this compare to "pure" 93-oct gas?
> 
> From a purely performance standpoint - what, if any, bad effects would ethanol blend have on our vehicles? I know nothing about ethanol and I tend to get little apprehensive when the media has nothing but good things to say about it. What do you guys think? Thanks.


The blend is weak. It will degrade your gas milage AND performance. Yes, the octane goes up, but actual power output from the same volume of ethanol vs. gas goes down... a lot. One of the engineers here explained it a few months back, something like: the BTU output of ethanol is like a quarter the power of gasolene. The octane is up, so to take advantage of it you have to run a very high compression to accommodate it, but then NOx emmisions go up as well. In your engine, compression designed to take advantage of gas will suffer a power reduction. As a result, the driver is inclined to pedal down more to restore the lost power which in turn wrecks gas milage. I think I got that right, but if someone else is more knowledgeable, please jump in...


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## bahearn (Jul 15, 2002)

Ethanol has roughly 65% the BTUs of gasoline. Its octane is indeed higher, but its energy content is lower. To properly use any oxygenate to full advantage, one must increase the compression ratio to regain some of the lost work due to the lower BTUs. Fuel injection fuel maps should be recalibrated to get the most out of the fuel and to prevent long-term engine damage (the engine is running lean, you see).


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## myoung (Apr 15, 2002)

The % of Ethanol will be less than 10%.. This was done in CA a couple years ago... It replaces the MTBE... The normal refined blend of gas will be one octane rating less, then the ethanol will be added to increase the Octane by 1.... so if you normally get 92 Octane in your area you will still get 92 octane once the mixture is completed and ready for sale..


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## Slayer2003 (Jun 4, 2003)

OOOOh, to live, in Japan. With their awsome octane. And cars that can run it no problems.


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