E30 (30% Ethanol fuel) is a dirt cheap version of 93 octane fuel. It's a 3:1 ratio of E15 (standard pump gas) and E85. 3 gallons of E15 (standard pump gas) to 1 gallon of E85. This will help avoid knock that you would otherwise get with high CR engines that feature a low lift/duration cam such as the one you
Do a 1:3 ratio then. 1 gallon 87 to 3 gallons of 91
