The simple answer to the Op's question is NO
I would run 2 tunes one for E85 an other pump 91/93 so you could switch when ever
how does this work with having leftover fuel in the lines or injectors from the opposite fuel, with a new tune? i guess what im saying is if you go running E85, then switch to 93....will there not be some mix? can that be dangerous at all? thats the question i thought of when going through the cons list ( be it rather small). I am in the same boat, i will be switching this spring after my motor is done.
You are partially correct.From my understanding, you wouldn't run into any problems going from your E85 tune to your... lets say 93 octane. The major difference betweeen the two fuels are their octane rating. Going from a higher to a lower won't do any damage because your tune for 93 will have less timing, so if you were under WOT you would still be covered by the higher octane of the E. It would be no different than putting Torco in your tank even if you're not tuned for it. Its just upping the octane and if your tune doesn't call for such a high octane, you will just be wasting it. Now switching from the 93 tune to the E tune is something different. You'll be looking for the necessary octane to safely run that timing and the 93 left in the lines will not be able to produce. I would take it easy for a while after switching back to the E after 93 to make sure its out, depending on how much 93 you have left in your tank.
Someone correct me if I'm wrong.
For sure! One can not look into just Octane Rating anyway. The cooling effects of Ethanol (Especially on a boosted car) make it act like a much higher Octane fuel.^^^ Thats why I said depending on how much he is mixing. I didn't want to get into ratio's and such, but you covered that as well. So its still awesome even if mixed with a half tank of unleaded.
:beer: