I wonder what the general consensus is with other members regarding higher octane gas (94) with ethanol vs 91 octane which is ethanol free.
I've been running 91 because it is ethanol free, however with all the upgrades done to my car, including Softronic. I wonder if going with a higher octane with ethanol will increase power, although I have read that ethanol has a lower BTU.
Re: 91 octane ethanol free or 94 octane with ethanol?
^^^There is definitely a difference between 91 octane and 93 (or 94) octane gasoline. The difference is more pronounced in turbocharged cars, but there is a small difference and the computer in our NA cars over time adjust timing to increase power slightly with 93 or 94 gas.
To the OP, I believe that ethanol, even though it may have a lower BTU rating the gasoline, actually increases the resistance to pre ignition detonation. Which is essentially all that an octane rating is: the higher the octane rating is, the higher its resistance to detonation. The higher any given fuel's resistance to detonation, the more a car's computer can adjust timing and increase power (to a limit). Bottom line, you're much better off using the 94 octane gasoline with ethanol if making power is your only concern. And btw, this is why one sees some very high-end turbocharged or supercharged exotic cars that are tuned to run on 85 ethanol and produce more power than they would on regular gasoline (i.e., the Koenisegg (sp?)).