Fuel Selection and Maintenance at Altitude - Colorado

  1. Rabbit

    Rabbit New Member

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    Doug
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    2017 Honda Civic Hatchback LX CVT
    I've got a 2017 Civc Hatch LX CVT and recently moved to Colorado. Altitude in my area is 5550 ft. Using a standard 3% loss per 1,000 feet, I'm estimating that I loose around 15% of my power.

    My question is about fuel. In Colorado, "Regular" fuel is 85 Octane. Not to be confused with E85; 85 Octane. This is because at lower pressure, fuel is more stable and detination less likely - or something like that. I have run 85, 87, and 91 with similar results. There is a feeling of lag with the 85, but no issues with knock. 91 makes the car feel more responsive but this might be in my head. I usually use 87, as that is the Honda recommended octane rating. But there is no * about operating at altitude.

    I can actually get 91 octane cheaper than 87 at the local Costco. Costco only has 85 and 91 nearby, and other non-discount stations offer 85, 87, 89.

    So, do you think I should run 85 ($2.20), 87 ($2.95), or 91 ($2.75)?

    Are there any concerns for the long term health of my civic that you would have while operating at altitude? Let me know your thoughts.
     
  2. latole

    latole Civic Lx 2018 Manual , Civic LX 2016 Manual

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  3. OP
    OP
    Rabbit

    Rabbit New Member

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    Doug
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    Something I'm considering is installing an aftermarket intake to help improve the uptake of oxygen and help curb some of the decreased performance and lost fuel efficiency.
     
  4. tacthecat

    tacthecat Senior Member

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    85 is fine and it'll be difficult to gain back the HP/TQ lost by the change in altitude.
    Remember my '68 RoadRunner being a slug when passing through Albuquerque during a cross-country jaunt.
     
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