As I said, the surest way to cause detonation in my engine is to run it where the POH says to run it.
From first-hand observation of measurements taken from a piston aero engine in a test cell.
Indeed, those measurements indicate that many big bore piston engines run in a state of mild detonation at settings that are uncontroversial from any perspective.
...hmm. Certification of the engine requires the manufacturer to demonstrate that the engine can be run
detonation free at the leanest fuel flow approved for each power setting in its manual, up to 103ºF and down to sea level. At leaner settings the engine may detonate up to so-called limiting detonation but those settings are, by definition, not recommended. In this buffer range, the fuel must be able to be reduced by 12% from recommended before limiting detonation occurs.
Therefore, a conforming engine run at the manufacturer's recommended settings (and fuel octane rating) is proven not to detonate. The flip side is that at the most critical recommended settings you do not have to stray far from the strictly controlled conditions of the test in order to induce incipient detonation to a class of APS delegates.
Understanding the certification requirement may also help people understand why the manufacturers do not recommend running lean of peak, even though they acknowledge it is perfectly feasible with the correct equipment. The engines were simply not tested for it as originally certified. Now, GAMI must know this as they finally did get an STC in 2015, and as per their website:
GAMIjector® and turboGAMIjector® fuel injectors, when properly tuned using the GAMI Lean Test procedures and with the aid of an every-cylinder EGT/CHT engine monitor, will allow the engine to operate in a wider range of fuel/air mixture settings than originally available when the Aircraft Flight Manual or Pilot Operating Handbook was first published
Nonetheless, the fact remains that a conforming engine is proven not to detonate when run at the settings recommended.