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89 or 91 octane is good for Civic?

Discussion in 'Engine Tech / Drivetrain' started by dihanp88, Mar 11, 2010.



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  1. dihanp88

    dihanp88 New Member 5+ Year Member

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    A friend told me to use 91 octane on my 1999 Civic LX 1.6 to get a better mpg... is it any true? I have been using 89 and my mpg is around 26-28... Some people say If it's a high compression engine then only you want high octane. what do you guys think?
    thank you
     
  2. RonJ

    RonJ Banned

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    Regular 87 octane only in a stock LX.
     
  3. terceltyler

    terceltyler The Silver Bullet Registered VIP 5+ Year Member 10+ Year Member

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    Agreed. Anything else is a waste of money unless you build the engine or are running boost.
     
  4. mpaired_7126

    mpaired_7126 New Member 5+ Year Member

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    when i got my d16y7 i used 91 on mines. nothing wrong but it just burns clean and fast. it doesnt hurt the motor however it hurts ur wallet. this was the time when gas was like five dollars a gallon.
     
  5. DarkCreep

    DarkCreep D16Y8+T Registered VIP Registered OG 5+ Year Member

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    Your friend is a dumb ass.

    I also have a few friends that are dumb asses and think that running 91 on their stock Civics gets them better MPG and more power.




    Dumbasses......
     
  6. Szady

    Szady D-Series Master Registered VIP Registered OG 5+ Year Member

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    I used to have a friend who put 93 in his 100% stock EG coupe with the D15b7. He told me it adds a few HP. :lol:
     
  7. 77amc

    77amc New Member

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    Yep it does get you better mpg! I've done it countless times.. (when I could afford it or wanted to 'clean out' a fuel system)
    From what I've read years ago, the higher octane actually slows down the flame travel so it burns more efficiently across the crown as the piston passes TDC and it pushes more on the downstroke of the rod.
    That's why on High comp engines, you will have pre-detonation or 'pinging' BEFORE TDC. If it was firing just after TDC, it wouldn't 'ping' at all because the resistance of the crank being at TDC would already be past and heading down the other side... Make sense to ya?

    NOW, what may be happening in a number of peoples engines is that gas stations are selling crap gas for premium prices and thus crapps out the O2 sensor, gives false readings to the ECU, cloggs up the cat, overheats it and forces the exhaust back into the engine eventually killing it...

    SO, Just do some cheap things first.. Check if your grounds are clean/tight, pull your cap, check for RED DEATH (red dust that is produced by dieing bushings, needs to be replaced) Scrape your connections inside cap/on rotor, (spray with good silicone) make sure timing is CORRECT (not 'by ear'. If timing is off you will be chasing your tail by adjusting other stuff that isn't the problem) Get some NGK V-groove plugs that are for your heat-range. Don't get all caught up with the multi-tipped plugs, You can't change physics of electricity! OHM-out your wires, should be around 1000/ft or less (less is more $$$)
    If you have a 1-wire o2, configure a 4-wired one. (it's helped me even on OBD-0! Minimal, but none the less) If your emissions will allow, header without the cat, OPEN up that exhaust. (enngines are AIR PUMPS, free it up)
    Do these or some, log your results per week, and make changes that your $$ alow, keep more logs and then help someone else out by making a thread.. Who knows, it might end up as a 'sticky'

    E
     
  8. RonJ

    RonJ Banned

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    No, this makes absolutely no sense for the Civic D16Y7 engine, which is specifically designed to run most efficiently on 87 octane gas. Running anything except 87 octane in this engine is at best a waste of money and at worst harmful.
     
  9. Esotericimage

    Esotericimage Try GOOGLE 1st Registered VIP 5+ Year Member

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    ron, u beat me to it after reading all that
     
  10. charlie brown

    charlie brown smokey Registered VIP

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    its crazy the car myths people bite into and waste money on
     
  11. bizoneoeh

    bizoneoeh Ex-Gang Member Registered VIP Registered OG 5+ Year Member 10+ Year Member

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    :lol:



    yeah.... 87 octane is what you should be using unless you're boosted then you should use at least 93. It's your money tho, you can waste it if you want.
     
  12. terceltyler

    terceltyler The Silver Bullet Registered VIP 5+ Year Member 10+ Year Member

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    You can use 91 too depending on your tune.
     
  13. tonyM

    tonyM caca poopoo Registered VIP Registered OG 5+ Year Member 10+ Year Member

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    truth, my car is tuned on 91. Hopefully not for long though.
     


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