static compression has little to do with octane needed for operation, the dynamic compression is what determines the octane level, several factors involved in dynamic compression, main one is camshaft timing events. I use an engine simulation program to determine dynamic compression. Performance trends will let you change octane, calculate dynamic compression, and calculate a timing curve to keep the engine from detonation. I have built some pulling truck engines that are required to run pump gas, and used a 13 to 1 static compression piston.