I think we have a failure to communicate. You seem to keep wrapping your head around a knock sensor an that was not what I was saying. I did not mention knock sensor, but a what is commonly called a predestination sensor or prediction algorithm.. Nothing like a knock sensor. Harley users a what the call an ion sensor system.
Bottom line is that, for the WK2, listening for ping and hearing none gives you false information.
My bad - I came back from a run and did some research. You caught me as I was trying to edit my post.
You might be right - or at least more right than I thought.
My switch from the automotive to the motorcycle and marine industries has left me a little lagging behind in that tech. I'm still seeing pezo knock sensors used, at least in the marine industry. I had forgotten about the Harley ION sensing systems on BTs (and didn't realize they went back as far as they do).
So you're right, it might be far more widespread.
That said, IF IT IS, that makes octane a much less important issue, since those systems are much more sensitive and better at preventing knock before any damage can occur. Yes?
Running the 87 at altitude is the same as running the mid at sea level. OP, you'll be fine. I lived in Denver for 7 years and even the dealers would say 85 is fine when regular was specified and 87 was fine when mid grade was specified.
Gasoline is gasoline, and contains the same explosive power, no matter which grade you use. Octane controls the burn (flame-front).
Too little octane for that engine-type means the gasoline may self-ignite from the high temperatures in the combustion chamber, pressure of the rising piston, or a hot-spot deposit on the piston or in the cylinder. This is called pre-detonation (ignition before the spark plug fires). When the spark plug finally ignites, you'll have two combustion wave fronts. When the two wave fronts collide, you'll get knocking. The PCM will retard the timing, lowering your optimal performance. This happens so fast, you won't even know it.
Too much octane for that engine-type means when the spark plug ignites the fuel mixture, the flame front is so slow that your don't get a complete burn, lowering your optimal performance. This unburned fuel goes out through the exhaust, affecting your emissions systems, specifically your catalytic converter. Also, because the exhaust stroke of the 4 stroke engine doesn't completely evacuate the cylinder, unburned fuel molecules remain in the combustion chamber, and will be deposited onto the piston, eventually building up, raising your compression ratio, requiring you to burn premium gasoline to stop pre-ignition.
Higher compression engines create more pressure and heat in the combustion chamber, just before top-dead-center. That's where your power comes from. Remember 13.5:1 compression ratios that required 104 octane? I know - I'm old...
Engineers have designed their engines for a complete burn, and recommend a specific octane to accomplish that. It's that complete burn that will give you the most power and mileage.
I operate just fine on a balony sandwich but will operate at maximum performance eating steak. I use 89 octane in my 5.7l cause it's recommended. Saying it's OK to use 87 is not good enough for me. It's your Jeep feed it what you like, I feed mine what the Jeep likes.