340 Pinging using 94

Detonation is most likely to occur at or near peak cylinder pressure which is where peak torque is. VE is highest at peak torque which is why cylinder pressure is at its highest. Lower RPM higher gear and introducing load (like climbing a hill with out downshifting) is when detonation will happen. You can make a 14:1 iron headed big block idle around town on 94 octane. I’ll say it again, if the noise he experienced happened on deceleration, is isn’t detonation.