Mixing gas - How to calculate octane?

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  1. #1
    488ci V10 Power
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    Mixing gas - How to calculate octane?

    Hellooooooooo,

    I usually only run 112 octane gas in my car and i was thinking about mixing in some 93 for the winter since i wont be doing any high boost stuff with the cold weather. Since my low boost setting is 23lbs i will need enough octane to cover that. Straight 112 is overkill since i've run 32lbs on that gas fine.

    The 112 is as follows
    Antiknock Index (R+M)/2 - 112
    RON, Research Octane - 114
    MON, Motor Octane - 110

    I'm wondering how much 93 octane pump gas i can mix in to be save for the boost im running. I'm thinking maybe 3/4 112 and 1/4 93, anyone know what the 93 octane stats are?

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  3. #2
    SupraForums Member HotSoup's Avatar
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    110+93=203/2=101.5 50/50 mix that should be enough for the boost you want to run.

    Jason

  4. #3
    488ci V10 Power
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    Quote Originally Posted by HotSoup
    110+93=203/2=101.5 50/50 mix that should be enough for the boost you want to run.

    Jason

    Are you sure 93 octane has a MON of 93?

    Im not sure 101octane is enough for 23lbs, might have to datalog it some to watch for knock.

  5. #4
    SupraForums Member StokerSix's Avatar
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    From logging timing on my '97 T78 car I've found that 100 MON is sufficient for around 25psi (~600rwhp). This is with leaded high octane pump mix. In addition, I've found that a leaded/pump mix performs better then the equivalent MON unleaded/pump mix.

    I'd watch your knock sensors since you have that capability though.

  6. #5
    SupraForums Member Taimur's Avatar
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    Here is a calcutor to give you the desired mix
    http://www.t72supra.com/Race_Gas_Formula.xls

    Informative post...
    http://supraforums.com/forum/showthr...ghlight=octane

  7. #6
    SupraForums Member StokerSix's Avatar
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    Quote Originally Posted by Taimur
    Here is a calcutor to give you the desired mix
    http://www.t72supra.com/Race_Gas_Formula.xls

    Informative post...
    http://supraforums.com/forum/showthr...ghlight=octane
    My results disagree with that thread.

    I would never consider running 26psi on GT104. I pulled ~5 degrees timing using TrakTec 105 unleaded at 23 psi.

  8. #7
    488ci V10 Power
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    Quote Originally Posted by StokerSix
    From logging timing on my '97 T78 car I've found that 100 MON is sufficient for around 25psi (~600rwhp). This is with leaded high octane pump mix. In addition, I've found that a leaded/pump mix performs better then the equivalent MON unleaded/pump mix.

    I'd watch your knock sensors since you have that capability though.

    Thanks! Im still trying to find the MON of 93 pump gas.

  9. #8
    SupraForums Member StokerSix's Avatar
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    heh. IIRC, 93 is 89 MON.

  10. #9
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    you should be able to do do 1/2 tank 110 and 1/2 pump for 23 easy. I run that sometimes with mine no problems.

  11. #10
    488ci V10 Power
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    Quote Originally Posted by Mad TKD
    you should be able to do do 1/2 tank 110 and 1/2 pump for 23 easy. I run that sometimes with mine no problems.

    Ok good! Im actually running 112 octane (110 MON).

  12. #11
    One wheeled junkie
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    Quote Originally Posted by HotSoup
    110+93=203/2=101.5 50/50 mix that should be enough for the boost you want to run.

    Jason
    i dont mean to steal the thread but i've been wanting to ask you this for a while now, what gas are you running??? whats your mods??? how much psi and whats your #'s????

  13. #12
    One wheeled junkie
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    dyno #'s i mean with mixed gas and with just 93

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