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math ?

jwb267jwb267 Member Posts: 19,651 ✭✭✭
edited August 2018 in General Discussion
2 gal. of 93 octane
2 gal. of 100 octane
1 gal of 110
what would be the octane rating
I am not concerned about the chemical aspects as one lowers the other
just the average

Comments

  • AzAfshinAzAfshin Member Posts: 3,117
    edited November -1
    5 gal. of 99.2
  • iceracerxiceracerx Member Posts: 8,872 ✭✭✭
    edited November -1
    quote:Originally posted by AzAfshin
    5 gal. of 99.2


    BINGO!

    Edit: (showing 'work')

    2 gal. of 93 octane
    2 gal. of 100 octane
    1 gal of 110
    5 gal of ????

    (2/5 * 93) + (2/5 * 100) + (1/5 * 110) =

    (37.2) + (40) + (22) = 99.2
  • jimdeerejimdeere Member, Moderator Posts: 23,185 ******
    edited November -1
    Az, show your work, please.
  • mag00mag00 Member Posts: 4,668
    edited November -1
    There may be more to it if you are trying to be precise. I don't know what the formula for octane is, and it may not be a linear formula.

    I checked and found a some calculation for "proof" and don't know if this applies.

    Example.
    It is desired to reduce spirits of 191 proof to 188 proof. We find that 191 proof spirits contains 95.5 parts alcohol and 5.59 parts water, and 188 proof spirits contains 94.0 parts alcohol and 7.36 parts water.
    95.5 (the strength of 100 wine gallons of spirits at 191 proof) divided by 94.0 (the strength of 100 wine gallons of spirits at 188 proof) equals 1.01.
    7.36 (the water in 188 proof) multiplied by 1.01 equals 7.43.
    7.43 less 5.59 (the water in 191 proof spirits) equal 1.84 gallons of water to be added to each 100 wine gallons of 191 proof spirits to be reduced. https://www.law.cornell.edu/cfr/text/27/30.66


    What I am saying is that the ratio of volume to octane may not be a linear equation. I would say that calculation is close, but could be as much as one octane point off. Could be more, or may not even matter.


    I would refer you to a specialist in volatile liquids if I knew one.
  • bpostbpost Member Posts: 31,944 ✭✭✭✭
    edited November -1
    quote:Originally posted by jwb267
    2 gal. of 93 octane
    2 gal. of 100 octane
    1 gal of 110
    what would be the octane rating
    I am not concerned about the chemical aspects as one lowers the other
    just the average


    Octane can not be determined by that method.
  • AzAfshinAzAfshin Member Posts: 3,117
    edited November -1
    Jim, you sound like my math teachers. Drove them batty, but that's how my mind works, too fast to write down [:D]

    bpost, given that octane is reported as per volume at gas stations, this method is correct. If it was by weight, then it wouldn't work.
  • Tech141Tech141 Member Posts: 3,787 ✭✭✭
    edited November -1
    83 Octane (well, 82.66 ....)
  • iceracerxiceracerx Member Posts: 8,872 ✭✭✭
    edited November -1
    quote:Originally posted by bpost
    quote:Originally posted by jwb267
    2 gal. of 93 octane
    2 gal. of 100 octane
    1 gal of 110
    what would be the octane rating
    I am not concerned about the chemical aspects as one lowers the other
    just the average


    Octane can not be determined by that method.


    Do you know something Sunoco doesn't?

    https://www.sunocoracefuels.com/tech-article/mixing-fuels-calculating-octane
  • gjshawgjshaw Member Posts: 14,621 ✭✭✭✭
    edited November -1
    93
    93
    100
    100
    110
    ____
    496


    496 dividend by 5 = 99.2
  • IdahoboundIdahobound Member Posts: 20,585 ✭✭✭
    edited November -1
  • jwb267jwb267 Member Posts: 19,651 ✭✭✭
    edited November -1
    thanks all for your replies
    I just need something a little more than pump 93. this should do it
  • iceracerxiceracerx Member Posts: 8,872 ✭✭✭
    edited November -1
    quote:Originally posted by jwb267
    thanks all for your replies
    I just need something a little more than pump 93. this should do it


    This calculator makes mixing ratios easy.

    http://www.bazellracefuels.com/Calcs/OC1.htm
  • jwb267jwb267 Member Posts: 19,651 ✭✭✭
    edited November -1
    I had saw that, but didn't know how to use 3 octanes
  • iceracerxiceracerx Member Posts: 8,872 ✭✭✭
    edited November -1
    quote:Originally posted by jwb267
    I had saw that, but didn't know how to use 3 octanes


    You can mix the ratio/octane you want with just two.
  • mag00mag00 Member Posts: 4,668
    edited November -1
    quote:Originally posted by jwb267
    I had saw that, but didn't know how to use 3 octanes


    I just played with that calculator and it came to 99.2

    You have to use trial and error to find it.

    I used the 93 and 100 first, and knew that was 4 gallons, the kept changing the desired octane until the mix came to 2 gallons each. That came to 96.5.

    Then changed the gallons to 5, used the 96.5 and 110 and changed the desired octane number until it came out to 4 and 1 gallons, and 99.2 worked.

    That being said, seems the straight math with ratio's (fractions) is fine.
  • pip5255pip5255 Member Posts: 1,614 ✭✭✭
    edited November -1
    sounds more like a tuning problem then a fuel problem, always tune em with what you plan on burning.
    just because you could doesn't mean you should
  • jwb267jwb267 Member Posts: 19,651 ✭✭✭
    edited November -1
    nothing wrong with the tune[;)]
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