i am looking for a car with a hemi in it. i found one and the guy said that it was professionally built to run perfectly on 93 octane. so does that mean that if i run it on regular gas, it will break the engine?
If you run lower octane than required you may get "detenation" also known as "knock" or "pinging". This is when the fuel explodes instead of burning properly. Timing can be retarded to compensate, but with loss of efficientcy. It can damage "break" things.