87 vs. 91 octane

Discussion in 'Fiesta ST Chat and Discussion' started by MLKN, Apr 14, 2014.

  1. Slowclimb

    Slowclimb Active Member

    Your motor...if you need the 2.50 or so per tank then go for it. Car runs better, less detonation, cleaner, more efficiently. I personally wouldn't run a forced induction motor on a low octane fuel...Not for a couple bucks a tank.

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  3. Neely2005

    Neely2005 Member

    First it's about $10 a tank here and second if Ford, the owners manual, the Fiesta ST supplement, my Ford salesman and my Ford mechanic all say 87 then I think it's safe to say that 87 isn't going to hurt the engine at all.

    And just for the record I filled up with 94 octane earlier today.
     
  4. Slowclimb

    Slowclimb Active Member

    Ok

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  5. reddog99

    reddog99 Active Member

    If he was getting knocking, and still insisted on running 87, then that's a dumb thing to do.
    But where's any evidence that the knocking caused the head gasket problem? It seems that you're jumping to unfounded conclusions.
     
    Neely2005 likes this.
  6. Slowclimb

    Slowclimb Active Member

    It was not me that denied his warantee. Subarus have had lots head gasket issues in the past. The motor design is such that there is a fairly thin section between the valves. The constant knocking or detonation resulted in that part of the gasket to fail...since the simultaneous firing of the cylinders was not what the motor was designed to do. Subaru took the motor apart and provided the explanation. Honestly I don't care what gas people put in their cars. Penny wise and pound foolish.

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  7. WScottCross

    WScottCross Well-Known Member

    You're paying almost $1.00/gallon more for higher octane fuel? For me, it's $.30/gallon. For $3.00 a tank, I'll take the better performance. I haven't seen better milage on higher octane, but I do like the power.
     
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  8. Slowclimb

    Slowclimb Active Member

    .20 cents here. I see bad mileage with 93...but mileage is not my motivator performance is.

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  9. Neely2005

    Neely2005 Member

    Here it's about 20 cents a litre more for 94 octane than 87 octane. 87 octane is $1.38 a litre here today.

    I'm not arguing that higher octane isn't better. I'm just saying that 87 octane won't hurt the engine.
     
  10. Zormecteon

    Zormecteon Active Member

    Since the factory says the car will run just fine on 87, it will. ... But the horsepower ratings from the factory also state that the 197 hp figure will only be attained on 93 octane. (or 92, I can't recall the the disclaimer precisely)
     
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  11. WScottCross

    WScottCross Well-Known Member

    I think we're all saying the same things. We just have different goals. I didn't realize you were in Canada, so now it makes more sense. I do agree that the car is capable of running 87 octane without damage to the engine.
     
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  12. Neely2005

    Neely2005 Member

    The horsepower ratings were obtained on 93 octane.
     
  13. Neely2005

    Neely2005 Member

    Yeah and the scary thing is that Canada has the second cheapest gas in the world.

    I'd really like to know what the horsepower difference is between 87 & 93. I asked my salesman if he knew and he said that there was a test with the Fusion and the difference was 1 to 3 horsepower.
     
  14. WScottCross

    WScottCross Well-Known Member

    I take most of what salesmen say with a grain of salt. Peak horsepower isn't the whole story, even if what he said were true. Throttle response, low end power and torque are a pretty big deal too. Those are what the car really fun for me.
     
  15. Neely2005

    Neely2005 Member

    Fair enough, I'll have to try to find the article that he was referring to and see how much detail it goes into.
     

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