[turbo23dog]

I don't support or deny what the mechanic said, but one thing I'd like to add is that increase in temp of the intake air will raise the threshold for engine detonation. Turbocharged engines normally have an intercooler set up to aid in cooling intake air to make more power which is related to reducing odds of detonation.

Most newer cars have knock sensors that automatically adjust engine management when the knock sensor is triggered that would prevent dammage.