Display MoreThere are a lot of differences when running the 2 different fuels, that require either a different tune or a alcohol sensor that allows the ECM to adjust.
One of the big differences is the target air/fuel ratio's for E85 and 93 octane are completely different. 93 octane pure gasoline has a stoichiometric air/fuel of 14.7:1 where E85 has a ratio of 9.85:1,
E85 tunes also have very different ignition timing maps compared to 93 octane tunes also.
Flex fuel vehicles have a alcohol content sensor for the fuel and blend the timing and target air/fuel ratio to adjust for the different conditions needed with the different fuels. Some of the aftermarket conversion E85 kits also include alcohol sensors to blend the fueling and timing correctly. However, if you just take a vehicle tuned for 93 and put in E85 it will not run very well at all because of the incorrect air/fuel and timing advance. I am guessing that the conversion that they were talking about on Velocity had one of those sensors or someway to adjust to the alcohol content.
When boosted like Kyle D , the problems with air/fuel and timing advance are even more important, as the margin for error when running higher boost is very narrow. Also, the E85 is giving a cooling effect that the 93 octane does not provide, making the engine also more prone to pre-detonation. Running 93 octane in a boosted engine tuned for 93 octane causes rapid disassembly of the engine There are certain aftermarket ECM's though that can use an alcohol sensor and adjust the air/fuel ratio, ignition timing, etc on the fly to adjust as needed though without having to completely retune with the changes in gas.
Is this a typo, or have I been on borrowed time for a while?