Who adjusts thier tune for the 10% or up to 10% ethanol at the pump these days...

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07-28-2010, 10:24 AM

#31

Atomic

I have a gauge for that

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While the ideal stoich ratio for E10 is around 14.1, E85 is around 9.76, so you can see why you need bigger fuel system and everyones gas mileage tanks. It should be noted both values are at lambda = 1. Ethanol is a good octane booster compared to gasoline so you can up the timing a fair amount

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07-28-2010, 10:34 AM

#32

dc_justin

Hello Dave

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Quote:

Originally Posted by BlackGMC

from my understanding is that would affect your airmass calcs. for example: you would be referencing the wrong value in your spark table, thus your commanded spark value would be a little off... Also your IDC would be up a little bit too.

But i have a question. is E85 and E10 similar? Meaning E85 contains 85% ethanol, and E10 contains 10% ethanol? Or am i way off... if i am not does that mean if the airmass was correct would we be able to get away with a little more spark due to the higher octane rating of ethanol? Or do i have things completely wrong???

With 87,89,91,93 octane, Ethanol is used as an additive in the final octane rating. E10 vs E0 should require the same ignition timing. Try a tank of E10, run it wide open, pull a plug. Put in a new plug, do the same on E0 and compare. Heat line on the strap should be in the same spot.