Let`s consider a stock Evolution.
Is there a change in the power output just changing the gasoline octane?
How many ponies I would have with:
87 / 91 / 93 / 96 / 105race gas? ? ? ?
I`m asking because I`m using a 96pump octane gasoline in my stock EVO.

 

I don't know mcuh about the programming for the stock evo, but I'd say you are wasting money with anything over 93. Sure it'll run better but the ecu won't take advantage that the price you are paying is costing.

Tho, maybe I'm totally wrong.

 

yes there is an increase and a decrease.. Running too low of an octane will burn too fast and can ignite before the spark hits it, causeing knock... Running too high of an octane will take too long for the cylinder to burn and will cause the charge to not burn completely.. I would run nothing more then recommended (94) on a stock motor, unless you are finding knock, which you shouldn't...

 

with a stock Evo and the stock ECU - you will not gain any extra power with the 105 ocatne race gas. You will probably not gain any extra power with the 96 octane either. 93 octane should be good enough. It should be high enough so that you don't have knock. With 91 octane there is a good chance you could see knock so stick with the 93 or above and you will be fine.

 

Thank you guys

 

BTW, The ECU is responsible for the knock sensor and adjust the timming based on many sensors including the Knock sensor, so the ecu should advance the timming untill it detects a knock. Am I wrong? ? ?

 

ECU will pull timing since the fuel is igniting before it should...