hey guys, I went to performance shop, called Rev Hard in illinois, and had 3 pull dyno run w/ wideband. I expected over 300Whp on my evo, but it read about 290whp. they told me because of gasoline. actually in my town, iowa city, there it no place carry 93 octane, but i just found one place carries 92 today.
Anyone can tell me about what is different between these?
is it much better for performance?
Thank you,

 

In short, running lower octane results in knock, which leads to detonation, which leads to a very unhappy engine. When your ECU sees or 'hears' knock, it reduces timing which in return hurts performance - but will be saving your engine's life. I'm guessing they told you that due to having some timing pulled from knocking. It's best to run the highest octane available, generally 93, in some states 91. You may also want to look into e85 which has a very high octane rating but requires a bit more fuel.

 

i got e85 right now and it works beautifully but the worst part about that is that i have to drive about 30 min to pick up gas. i say you just use what ever is easy for you to fine.