E85 does not pre-ignite lean. One reason 15% gas is added to aid in combustion. Although E85 will auto combust rich. These scenarios are the exact opposite of any other fuel and why most people give up on its use. BUT, ....perfect for forced induction cause a lean mixture(like99% of forced builds happen) will not self explode the engine due to pre-ignition.
Ideally when tuning, is to start rich and work into the proper mixture. Doing so E85 complicates cause knock happens and E85 burns so clean its next to impossible judging the mixture condition from the tail pipes. Reading spark plugs with E85 is difficult as well. The stuff is super clean!
BTU rating is roughly 50k units less than gasoline making it a much cooler combustion. Fuel entry into a hot chamber has a massive cooling effect over gasoline due to E85 not vaporizing as easily also aiding in chamber cooling when the rpms are high....Needless to say, E85 loves to run lean! E85 is totally the opposite of gasoline.
