Atkinson motor and fuel octane

[tsled]

Yup, exactly, high loads and higher temps are more likely to cause knock, and so you'll benefit more from higher octane in those conditions. Not sure if I mentioned it here or another forum, but that's why I run 93 octane on my Ram 1500 during the summer months especially if towing because TX can get really hot and with an engine at ~150K miles its bound to be a bit carboned up which create hotspots that again are more likely to cause ping which the higher octane can abate.

But like any 2022 MY vehicle that says it recommends 91 or 93 octane such as the Ecoboost 2.0, it will run fine on 87 octane, but it may see reduced fuel economy and horsepower because of the way the system is protecting the engine from knock, generally running a bit richer and with altered timing that reduces power. There are limits to how much those tricks work though, so don't run 91 octane recommended Ecoboost 2.0 on below 87 octane fuel (which isn't even on most pumps anyway).

Regarding ethanol, they are just warning that this isn't a flex-fuel vehicle so not to run more than 15% ethanol, but typically for "normal" gas it will either be ethanol free or have only 10% ethanol which is low enough concentration its not going to mess with any fuel lines or components in the fuel tank like high ethanol fuel can for components not designed for it.

tl;dr: In the cooler months and if you're driving relaxed and not towing, save money and run your ecoboost on 87 octane. In the hotter months, when towing, when you want all the horsepower you paid for, or when mileage is getting high (especially on a direct injection turbo engine that is more prone to carbon deposits forming), run 91+. For the hybrid, just run 87 all the time.

How would the use of a cold air box and/or a less restricted air filter play into this?

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