If we imagine the combustion flame spread it should be likened to a surge that there is in the impact of a water drop on the surface of a pond: After hitting the water drop to the surface of stagnant water pond generated a small circle wave that grows every moment to reach all the dock.
Spread of flame burning in this way led to impact of homogeneous blast wave, strong and steady on the piston crown. However, if the several drops strike on different area of water level, numerous circular waves produces in various stages that after growth and spread collide to each other and cancel each other out. Combustion destructive waves are like such waves of pool: produce in various stages and exert interaction effects on both and cancel each other out. In this case, the internal pressure of the combustion chamber rises with harmful vibrations and high temperature wasted engine mechanical energy. If the fuel does not have correct octane (in accordance with the opinion of manufacturer and engine compression ratio) become reactive earlier than the regular time and flamed before the piston reaches to top dead center and before ignition the spark plug, it is clear this consequences.
Unfortunately, the image of most people is incorrect that have about super gasoline. Super gasoline is slow-burning than usual gasoline.
In such fuel, additives make that gasoline more slowly burning. Conventional fuels in cars that have compressions ratio 7/5 to maximum 8/5 to 1, responds well. While super gasoline can be used to compression ratio 9/5 to 1.
The second important difference as mentioned above is igniting early and emitted irregular waves (release of several focus) by conventional gasoline explosion which caused harmful tensions in the cylinder body while waves of super gasoline combustion released uniform from the spark plug to piston crown. Of course use of gasoline with high-octane is not necessary for conventional engines with low compression ratio and there will be no improvement in engine.
In this regard octane can be likened to shoes: tight shoes off your feet and make you running bad and even hurt to foot but wide shoes will have no impact on your better running.