What do make the knocking noise in the engine when you give gas?

To many possibilities, a mechanic really needs to hear this noise to be able to make a diagnosis.

Have it checked by a knowledgeable person that can hear what kind of noise it is. It may even be an octane ping that sounds like a knock to you. May not be the engine, but maybe the gas you are using. Just a thought.

Timming gears....going bad need replaced..