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91 or 94 Octane.

Discussion in 'Engine/Tuning' started by RCMPSVT, Sep 23, 2020.

  1. RCMPSVT

    RCMPSVT Well-Known Member Established Member

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    So my car is tuned for 94 octane with a can of boostsane octane, makes 20PSI. Took car in today to local mechanic and he was checking it out and we got talking about fuel. He told me I’m Better off running 91 octane cause after 91 all it is is ethanol blend to make it 94. I don’t plan on changing off 94 but does 91 actually run better than 91?


    Curious.


    Thanks.
     
  2. TP03

    TP03 Active Member Established Member

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    Nah. Don't listen to that. Old way of thinking is "ethanol is bad". Only worry if any is having an ethanol blend sit for a while in the tank like during storage. Ethanol likes to attract water/condensation. More octane will always run better if your timing is advanced for it. More timing on less octane and you're asking for trouble.
     
    me32 likes this.
  3. 13COBRA

    13COBRA Resident Ford Dealer Premium Member Established Member

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    DO NOT listen to that local mechanic. LOL
     
    me32 likes this.
  4. DSG2003Mach1

    DSG2003Mach1 Well-Known Member Premium Member Established Member

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    leave it be with 94 + boostane. Even if they were just blending #85 with it to bring it up from 91 (which i doubt) the anti knock/detonation properties of it would be a bonus not a bad thing.
     

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