I've travelled across the country in many states and never have had a problem in Top Tier stations with 87 octane gas. Spending more money than I need to has never made me happy.... Petroleum refining today has really good controls. However, if you think a certain gas station is cheating on you, I'd go to a different station...I'm not sure what horsepower has to do with spark knock or low rpm acceleration. Torque on the other hand is directly impacted by both. Low rpm acceleration is one of the peak conditions resulting in detonation. Detonation results in less sustained push on the piston, providing less torque at the crank. Retarding the spark, or any other means that the ECU can take to reduce detonation, results in a less efficient combustion versus piston position. Once again, less torque (the necessary force required for acceleration).
I do concur with the rest of your argument regarding not getting an increase in power (hp or torque) by using more than 87 octane in our engines. But, I error on the side of pumping a higher octane to ensure that I always am getting at least 87 octane (I can assure you that even at Tier 1 stations of the same brand, the octane rating of the fuel dispensed can vary from station to station.
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