In my country are sold gas with different octane number (RON: Research Octane Number): 88, 90, 92, 95, 97, 98, and the latest is 100. RON-88 is still sold since still many old cars, motor bike, and agriculture machines which are using low spec gas. RON-90 is intended for transition, as alternative in case customer want to move forward using better gas but not so expensive. In our country, the higher RON, the more expensive.
As we know, every engine is designed with a specific compression ratio, and that RON is very related to the compression ratio. But many times I read explanation from automotive services claiming that higher RON will be better for car. Not specifically explained which car and what kind of car. Indeed we know that most cars are now having compression ratio 10:1, which according to the petrol producer that kind of is car suitable using petrol with RON 92-95. In my understanding, the compression ratio is related to the Top Dead Center (TDC), which it will produce specific compression that will compress the petrol inside ignition chamber, so it will increase temperature just before ignited by the spark. That compression made engine got hotter. If an engine with specific compression ratio is fed with petrol with RON-88, the petrol will be burned before TDC. Vice versa, if that kind engine is fed with RON-100 petrol, than the petrol will NOT be completely burnt. Hence, the automotive service claim is wrong.
So my question are: 1). am I right with my understanding? 2). for that 10:1 engine, if it fed with lower or higher RON, what will be the impact to the engine?