Question : CARS running on RON97 petrol
may encounter "knocking" of the
engine when changed to RON92.
What is meant by "knocking"?
You probably have read this elsewhere but basically,
anti-knock additives actually slow down the burning of the air-fuel mixture in the engine.
When the compression ratio gets too high or the fuel does not have sufficient anti-knock additives,
the air-fuel mixture will detonate (explode) instead of burning,
resulting in a "pinging" or "knocking" noise coming from the engine.
When this happens, there is a very high pressure rise in the cylinder
and if it is allowed to continue, you could have piston and piston ring failure.