93 octane tune… but I can only get 94

[MediumThicc]

Hi guys, new to FiST life and loving it… I have a question about octane use. As the thread title suggests, I am currently running a stage 1 OTS COBB tune while I wait for parts and a stratified tune. The current tune I am running from COBB is the stage 1 93 octane tune and so far it seems to be okay. Only issue is that I can only find 94 octane around me. Is this okay? Or would I be better off to switch to the 91 tune and run 91 octane which is available everywhere around me.

Thanks in advance.

 

[RubenZZZ]

Octane is a measure of how much resistance a fuel has to ignite. The higher the octane reading, the less chance of pre-ignition( uncontrolled pre-ignition or "engine knock" or "pinging"). Im sure someone will correct me if im wrong.

91 octane is less resistant to knock than 93, and 93 is less resistant to knock than 94.

Run the highest octane you have available (93/94) with a 93 tune. If you run 91 there may be a chance for some engine knock and reduced performance as the computer will
compensate to avoid engine damage. 93/94 octane would be fine on a 91 tune.


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[MediumThicc]

Awesome, thanks for the detailed answer. So I will stick with my 93 tune and run 94 pump gas that I can get. Maybe eventually I’ll switch to 91 gas and 91 tune and see what that’s like but from what I have heard. The OTS or 93 tunes are supposed to give marginally better torque.

 

[slopoke]

I'd stick with the 93 tune. Since you have 94 octane fuel, I'd use it. You should be able to make the most power that the 93 tune has to offer.

 

[subzerospeed]

do not use a 93 tune with 94 gas, assuming its chevron 94e0 or any brand that is non-ethanol...that specific gas is shit and your wayyyy better off running a 91 tune and getting 91e10. plus youll save some change running 91 and not specifically 94..chev 94 is trash. non-e gas is meant for hotrods with carbs..

 

[MediumThicc]

do not use a 93 tune with 94 gas, assuming its chevron 94e0 or any brand that is non-ethanol...that specific gas is shit and your wayyyy better off running a 91 tune and getting 91e10. plus youll save some change running 91 and not specifically 94..chev 94 is trash. non-e gas is meant for hotrods with carbs..

Hmm okay interesting. I’m gonna go check what ethanol content it is at the gas station. So you’re staying I would want to have SOME ethanol then?

also I’m up in Canada and the gas stations that have 94 readily available are PetroCanada but if its 94e0 then I should throw the 91 tune?

 

[subzerospeed]

Hmm okay interesting. I’m gonna go check what ethanol content it is at the gas station. So you’re staying I would want to have SOME ethanol then?

also I’m up in Canada and the gas stations that have 94 readily available are PetroCanada but if its 94e0 then I should throw the 91 tune?

i see that, i have never bought gas on the east coast of canada only the west coast, and i never had good results in my subarus running Chev94E0. the cars pulled less timing whenever i used Shell91E10, or when i lived in AB and found Husky94E10. E content is the main thing here, if that PetroCan is 94E0, i would not use that and run 91E10, ethanol really makes a difference when it comes to timing getting pulled and having negative corrections.

if you dont have 94E10, find 91E10 and run a 91 tune. its a cobb ots, its not really gonna make a discernable difference on a mostly stock fiesta.

 

[Ford ST]

https://www.petro-canada.ca/en/personal/fuel/gas

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