87 octane in the 2.4 turbo

Discussion in 'General Subaru Discussion' started by Cotts612, Dec 4, 2021.

  1. Cotts612
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    Cotts612 Well-Known Member

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    I'm on the Outback forum, and apparently people are running 87 in their OBXT's, and Ascents, with the 2.4L. Subaru recommends 87 or higher. Man, I feel like that is just asking for trouble. I wouldn't even touch 91 in the cities for my wrx, only went for bp 93. I mean, how much power are they losing with the amount of timing being pulled. Jeez. Plus, these vehicles are big, so they're in boost a lot more often than a 3200lb car. Any thoughts, or am I missing something?
     
  2. euro
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    euro Well-Known Member

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    There's a few thread here on this already but if subaru is recommending 87 or higher and it's bone stock just run 87-88 (some stations don't have 87). You gain nothing running higher octanes in a car tuned for 87ish.

    Added thoughts:
    I've never heard of a turbo with a factory recommendation of less than 91 premium before.
     
  3. Cotts612
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    Cotts612 Well-Known Member

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    That's what I mean. Its crazy! I suppose putting premium in when it's already "safe" for 87 wouldn't change the power output, but it sure would be safer. Apparently, dealerships are telling people that you might hear knock, and that it's fine. :facepalm:
     
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  4. euro
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    euro Well-Known Member

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    I had a hyundai veloster na they suggested 1/4 capacity oil consumption was considered was "normal" below 100k miles. Reality check was follow their rules and the recall warranty is valid
     
  5. tangledupinblu
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    tangledupinblu Event Coordinator Staff Member

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    Seems strange to me. But, they are professionals!:unsure:
     
  6. WRX1
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    WRX1 _ Staff Member

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    You also have to remember that 98% of everyone never would "need" the high octane. Just cruising the freeway, you are spinning a small low compression engine. Probably could get away with 70 octane. Then factor in that most modern engines/ecu packages bounce off of the knock sensor all the time anyways. They will constantly add timing until the knock sensor goes off. It is a easy way to maximize timing to improve fuel economy.

    I have seen tunes on some cars that picked up 8-10 mpg just adjusting the off boost low load timing tables. Mileage is all about efficiency, so the more timing you can run the better the mileage. Since most people buy a car more off of mileage then absolute max horsepower, the factory will maximize where they can. Then add in the increasing federal mandates, you can't expect every company to just recreate everything to make these federal mandates.
     
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