Anyone use regular gas in their Si?

  1. amirza786

    amirza786 Senior Member

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    Premium only benefits high compression engines where 87 is prone to pre-ignition. An engine that doesn't call for premium gets zero benefit from it. An example of this is putting race stripes on a Yugo and giving it an expensive paint job. It might look pretty, but your not making it even .0001 second faster.

    I have a thread on regular versus premium, check in out when you get a chance
     
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  2. BigDog

    BigDog Senior Member

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    Ditto with the exception that I did use 91 octane for 2 months to see if there was a difference in MPG. No appreciable difference in MPG between 87 and 90+ octane. Plus I'm saving $60/month by filling up with 87 so I've saved myself almost $1,200 in fuel costs over the 2 years I've owned it.
     
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  3. Memogiyi

    Memogiyi Member

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    Awesome! Will do.
     
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  4. Micah

    Micah Senior Member

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    Eh...there are other situations where it can benefit. High mileage engines with buildup on pistons, cylinder, and valves can result in wonky compression numbers. Higher octane fuel can stave off knock at just a few dollars per tank. For many people, that is preferable to fixing the issue. Arguably the wrong solution, but it keeps it going.
     
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  5. amirza786

    amirza786 Senior Member

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    I have a 2013 Toyota Sienna, 3.5L V6, it takes regular 87. We do a lot of long trips on it, mountain roads etc. Many times I'm tempted to put in premium when we go on long trips, I think maybe I'll get a bit more performance out of it's V6. The truth is it was not designed to use premium, there would be no benefits and I would be paying an additional $10 to $15 to fill up that big tank... For not.

    In the case of an older car designed to use 87 but is knocking, it's either time to see the mechanic or the junkyard. If neither is an option and premium works, I guess that would be the exception
     
  6. thebutcher

    thebutcher NSFW

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    It’s funny how so many people commenting here believe their smarter than the Honda Engineers that built this engine. Do you really think they didn’t consider the facts for what would happen to this engine if only regular unleaded gas was used? Reading your comments always make me laugh.

    Will premium gas make the engine perform better? Yes.
    Will premium gas give better gas mileage? Yes.
    But nothing noticeable because it’s so small.

    Will regular unleaded hurt this engine? NO
     
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  7. amirza786

    amirza786 Senior Member

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  8. Micah

    Micah Senior Member

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    Knock knock...
     
  9. gtman

    gtman Senior Member

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    Color me confused. I mean, I get it, 87 is more economical. But didn't most of you guys get an Si for handling and power? It may run on 87 but you're not getting the advertised power on it.
     
  10. ebhaynz

    ebhaynz Senior Member

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    Honestly if my Si drove significantly faster or peppier with premium I'd consider it..I just don't see any performance improvement at all. I love this Si, it's a blast to drive, it's the best Civic and best Si ever no doubt about it. More importantly I'm very thankful I have a stick shift in a world(U.S.) where they are becoming rarer and rarer every year.
     
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  11. gtman

    gtman Senior Member

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    #86 gtman, Sep 15, 2019
    Last edited: Sep 15, 2019
    Here's an old post showing dyno numbers on 87 versus 93 octane on a stock Si. 15 more hp at the wheels and 12 more tq is nothing to sneeze at. The dyno was done by Vit Viper so I believe the numbers are legit. Unfortunately, the link to Vit's blog no longer works but I remember reading the dyno info there a couple years back.

    IMG_20190915_062654.jpg
     
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  12. REBELXSi

    REBELXSi Señor Member

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    Imagine how much we'd pay in aftermarket parts just for that boost.
     
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  13. BigDog

    BigDog Senior Member

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    I'm in the same boat. My primary goal was to purchase a fuel efficient vehicle since I put a lot of miles on my car. When I saw the Si, I had a chance to get a sporty looking economy car with a manual transmission and I was sold. It's peppy enough to take it out and have fun on occasion and efficient enough that I'm saving a lot of $ when it comes to fuel costs.
     
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  14. SichuanHot

    SichuanHot Senior Member

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    With a fuel tank having as small volume as it is, paying the slight extra for 91/93 is worth it and the car seems to like it from my experience so far.
     
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  15. BigDog

    BigDog Senior Member

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    For 99% of the Si drivers out there that's most likely the case. In my case, I've already put 1,730 gallons of gas in my Si in the last 22 months. Premium gas (91 octane around here) costs between $0.60 and $0.75 per gallon more, so I've saved in excess of $1,200 so far with no appreciable difference in MPG. With that savings I've covered the cost of insurance for those 22 months.
     
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