I run the factory chip @ factory boost. When I saw E85, I was in corn country at a grain elevator. None nearby that I have seen here. Octane is a ratio. I looked it up as chem class was a long time ago but it is still the same.
The name "octane" comes from the following fact: When you take crude oil and "crack" it in a
refinery, you end up getting
hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different
fuels. For example, methane, propane and butane are all hydrocarbons. Methane has a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has
eight carbons chained together.
It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.