If knocking occurs, usually the first to blame the fuel. There is a possibility octane does not fit (mixed retail purchase kerosene?).
Octane rating is often associated with the compression ratio. In general it is correct, but there are several other factors that will determine the octane requirement. Among the surrounding air temperature and operating altitude (altitude) of the vehicle.
She's supposed to heat the air around it will slightly decrease the octane requirement. And he said also, the higher vehicle operating areas also contribute to determine the octane rating of the ideal.
It is said that the relationship between the tables and the octane value of the compression ratio is generally taken from a research laboratory postscript usually at a temperature of about 24 degrees C.
Common graphic relationship between compression and torque roughly like this:
