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Old 06-11-2009, 07:30 PM
  #21  
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Originally Posted by samnavy
What's the octane rating of E85 and can I mix it 1:9 or 1:8 with 91 and still be OK without changing the tune?

Depending on composition and source, E85 has an octane rating of 100–105 (from wiki)
Also see this: E85 in standard engines - Wikipedia, the free encyclopedia

Lot's of good info there
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Old 06-11-2009, 07:36 PM
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I believe 105 (R+M/2) is the commonly quoted number, though I've heard it tends to vary a few points +/- depending on the gasoline component and the actual amount of ethanol (which can be as low as 70% and still legally be branded E85.)

You're already running E10, so adding 15% of E85 (assuming an actual 85% E component) would give you about E21.

The problem with E85 is the energy density. E10 contains 33.7 MJ/L, while E85 is rated at 25.6 MJ/L. So for any given HP, you need about 1/3 more fuel by volume. (This is why E85 cars get lower mileage and have larger injectors.)

edit: nicacus beats me to the punch
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Old 06-12-2009, 12:40 PM
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Originally Posted by samnavy
Most people know you can get 93 almost everywhere in the country except CALIFORNIA!!! We only have 91 here, and race gas purchased at a speed-shop is usually ******* retarded expensive, and there might be 2 or 3 places in all of Socal you can get that **** at the pump.

Also, start at the Mexican border and drive north... do you know when you reach the first real drag-strip or road course? It's about 1/2 hour north of LA. Yup, in all of San Diego/Orange/LA/SanB/Riverside/Imperial Counties, there is one 1/8mile dragstrip at an Indian reservation. That's it.



Irwindale has a 1/8 strip. They have unleaded 101 and 110 leaded pumps there too.
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Old 06-12-2009, 02:39 PM
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Originally Posted by samnavy
What's the octane rating of E85 and can I mix it 1:9 or 1:8 with 91 and still be OK without changing the tune?
You gotta go with a MS2 since you're looking for a 99, correct?

If so, you can get a flex fuel sensor and not worry about getting the ratios just right. As it is, e85 only means it's a max of 85%.

Flex Fuel with MegaSquirt

The EVO board has alot of interesting info on e85 tuning, they're way ahead of the Miata curve in this aspect.
E85 tuning notes - evolutionm.net (Sorry for the thread jack)

Chris
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Old 06-12-2009, 02:50 PM
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Talk to Chris Swearingen. He's running E85 (or preparing to, anyway) in his supercharged SM2 car. When I built his MS2, we set it up for the FlexFuel sensor.
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