My understanding of NORTH AMERICA octane rating or AKI:
1). 87 octane and 94 octane have the same burn ENERGY. Meaning, you are not magically gaining HP or saving fuel. They have the same amount of stored energy.
2). Difference as octane number increases, is the additives that make that particular higher number BURN at a slower rate. In otherwords, igniting 94 octane is slowed vs 87. This is why relatively Higher compression engines, like 370Z ,require Minimum 91 in order to prevent detonation/pre-ignition due to heat and not during spark event.
91 is what Nissan engineers came up with after multitudes of tests.
3). The 370z ECU is smart enough to figure all this out if it gets a signal from the Knock sensor (not sure if its smart enough to understand the severity of the ping) and adjust timing accordingly.
To say accurately what will happen with 87 Octane at grandma speeds, Id be a liar. I'm sure OAT, engine temps, water temp, all will be a factor.
I would at least go to 89 octane minimum. I don't screw around, for .05c/litre more over 91, I use Chevron 94 which is Ethanol free. All 91 have ethanol here with the exception of Shell. (I'm west coast Canada)
Nothing wrong with Ethanol and modern cars. The rubber components are made as such. As long as you are driving with it and tank is continuously re-filled. DONT store with Ethanol gas!! I'm spring/ summer only and I store rest of time.
Please correct me if I'm wrong.
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