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  1. #1
    zornet's Avatar
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    Octane Blend Charts…

    These Charts may help achieving the optimum Octane of 93 (R+M)/2 for our Cayman’s. The first Chart is for a base of 91 (R+M)/2 followed by a second chart for a base of 92 (R+M)/2 blending with 100 (R+M)/2 Race Fuel. Remember any rating over 93 (R+M)/2 your wasting $$.

    --- 91 Octane Base ---


    --- 92 Octane Base---


    zornet
    Last edited by zornet; 10-21-2006 at 10:24 PM. Reason: Post Oct ’06 Migration clean-up.


  2. #2
    fuserchris is offline Porsche Enthusiast
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    Could just be the 2 hours I spent playing basketball in the sun but, what does this graph mean? or anyone who understands what they're looking at please explain.

  3. #3
    zornet's Avatar
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    For instance If you had 5 Gallons of 92 Octant (left column) and bended 1 gallon of 100 Octant you would then have a blend of 93.3 Octant. At one time I’d seen a chart that included more starting Octane ratings from 89 up, if I find it will be replaced.

    zornet
    Last edited by zornet; 10-21-2006 at 10:25 PM. Reason: Post Oct ’06 Migration clean-up.

  4. #4
    iota is offline Porsche Chatter
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    Just buy 100 octane gasoline and mix it into your tank. This way you know how much of which to mix to create 93 octane in case it isn't available in your area. I'm pretty sure thats what it means.

  5. #5
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    Just out of ignorance & curiosity....Out here in the U.k., all the petrol stations display ' Premium, or Super Unleaded at 98 Octane'.....This appears as standard......There is no other choice of lowerunleaded petrol from what I can see......


    Does that mean we regularly, unwittingly fill up on 'Racing Grade' fuel.....?

    Edited by - Doc_Rishi on 06/11/2006 3:54:58 PM

  6. #6
    grant's Avatar
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    In Europe, you use a different measurement standard. 98 here in US is much higher than 98 there in UK...
    1973 Carrera RS 2.7 Carbon Fiber Tribute (240hp and 1,890 pounds)

  7. #7
    fuserchris is offline Porsche Enthusiast
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    For instance If you had 5 Gallons of 92 Octant (left column) and bended 1 gallon of 100 Octant you would then have a blend of 93.3 Octant.
    At one time I’d seen a chart that included more starting Octane ratings from 89 up, if I find it will be replaced.[/quote]


    zornet [img]/fckeditor/editor/images/smiley/MWPX/wall.gif[/img][/quote][/quote][/quote]


    [/quote]


    Ah, I get it now. Thanks for that clarification zornet. Also, when I first looked at this thread I was using the PC in the lab rather then my regular desktop and it omitted the 2nd chart for some reason. I think I was just having a hardtime figuring out what 92 in the first chart meant, 2nd chart would of gave it away :[img]/fckeditor/editor/images/smiley/MWPX/lightbulb.gif[/img]

  8. #8
    zornet's Avatar
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    fuserchris - No fear, it wasn’t very clear. Also the 91 Octane chart was added after the fact.

    zornet
    Last edited by zornet; 10-21-2006 at 10:25 PM. Reason: Post Oct ’06 Migration clean-up.

  9. #9
    fuserchris is offline Porsche Enthusiast
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    How do we know that 93 octane fuel would be the highest grade fuel that our Cayman could take advantage of?

  10. #10
    zornet's Avatar
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    As stated my beez in an earlier trend whom I think explained it best.


    So yes, when you are used to running 91 octane and you mix 91 with some racing gas of 96 or 100 octane, the car will probably run a little better and smoother, but anything over the 93 mark - whether you're mixing it or pumping it straight in, is a waste of money. In order to take advantage of higher than 93 octane, you have to either re-map the ECU, tear the motor down and put in higher compression pistons, or both.

    On turbo cars with computer controlled boost, putting in higher octane gas makes a huge difference - the ECU is programmed to allow for it, and the boost comes on faster and with much more 'malice' than with lower octane gas... oh, yeah - then there's the price of the initial investment...

    brad

    zornet
    Last edited by zornet; 10-21-2006 at 10:34 PM. Reason: Post Oct ’06 Migration clean-up.

  11. #11
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    <hr style="width: 100%; height: 2px;" />quote - How do we know that 93 octane fuel would be the highest grade fuel that our Cayman could take advantage of?

    fuser
    <hr style="width: 100%; height: 2px;" />fuser,
    It says so in the owner's manual, and inside the fuel filler flap - the cars are optimized for 93 octane - US octane, that is. How the computer handles it is decided by a number of factors - ambient temperature and air density (at temps over 68 degrees F, the computer begins to retard timing and power to handle early detonation), load on the engine, octane of the fuel being used, among a host of other things, too. Once you get over the 93 octane that the car is optimized for, you're just paying for higher numbers, not higher performance.

    brad

    Edited by - beez on 06/14/2006 09:46:05 AM
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  12. #12
    fuserchris is offline Porsche Enthusiast
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    Thanks Zornet and beez,

    I know there was a thread stanarded by mpollard about the price of high octane fuel sometime back, but out of curiousity what do you guys pay for your high octane fuel?

    Here the only station serving this fuel charges 8.49 per gallon if you purchase 5 gallons at a time, and 7.49 per gallon if you purchase 50 gallons.

  13. #13
    zornet's Avatar
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    fuserchris - If your down from Santa Barbara some time this is thetrend mpollard posted --- "http://www.caymanclub.net/topic.asp?...wport Hills NB.

    Search capabilities of the site are quite good.

    zornet
    Last edited by zornet; 10-21-2006 at 10:33 PM. Reason: Post Oct ’06 Migration clean-up.

  14. #14
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    I haven't bought racing gas in quite a while - last time was end of last year for a track day at Laguna Seca with the 996 turbo, and I paid $4.95/gal. I'm sure that bears no resemblance to current prices... it sure made the turbo fly like a bat out of hell, though.

    brad
    22-year PCA Member
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  15. #15
    Santa Fe's Avatar
    Santa Fe is offline Cayman Enthusiast
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    high octane in turbos is worth it as beez says. non-trubos are a diffent kettle of dollars.


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