Thanks Mainia1, some people, have no idea what detonation is, let alone to what it sounds like. Valve clatter is not pinging either. Pinging and detonation (engine knocking) are different and caused by the same issues.Nope, it is detonation, I have spent years tuning 12:0 to 1 engines on pump gas that had zero ignition technology on all different types of cars. I know the sound well and every elevation of octane reduced the sound. It is a no brainer.
This is a two good explanations; https://www.enginelabs.com/news/detonation-what-causes-it-and-how-to-control-it-using-efi/
Blessings and Peace