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    use 100 Oct. racing fuel

    Can I use 100 fuel for 997S?
    By the way, I am at California.

    Re: use 100 Oct. racing fuel

    p9972005 said:
    Can I use 100 fuel for 997S?

    Sure you can but you are giving away octane. US Porsche engines are designed for octanes up to 93 while the CA standard is 91. Anything above a 93 is a waste (assuming factory ECU). Check out the text on the fuel cap door. IIRC, it specs 98 RON and min 91 (R+M)/2, the US measure which is the ave of the Research (RON) and Motor (MON) octane numbers. Does anyone know how much peak torque is lost for an octane drop from 93 to 91?

    Re: use 100 Oct. racing fuel

    Are you sure? I filled my car up with 94 Octane fuel while up in Vancouver BC recently and my Turbo seemed to feel a bit stronger after driving a hundred or so miles on the higher octane fuel. That's after giving the ECU a chance to "adjust" to the higher octane fuel.

    Re: use 100 Oct. racing fuel

    HI guys I run on 100 octane as in Greece we have available 95, 98 or 100 octane fuel

    Shell is called Vpower Racing
    and Bp ultimate



    by the way the car loves it and I also used it in my 330 ci cab for three years without a problem.

    Re: use 100 Oct. racing fuel

    Mix it 50/50 or 60/40 and you will likely see the same results unless you get a chip for your car. There are some chips which can be adjusted for 93 or 100 Octane. These will make full use of the 100. It's like a tank of rocketfuel in that case (and not just because of the NASA size fuel bill).

    Re: use 100 Oct. racing fuel

    Is it true that racing fuel can contain lead that will destroy your catalytic converter?

    Re: use 100 Oct. racing fuel

    Florent, you are referring to 95, 98 and 100 RON octane.

    In the USA, they don't use RON. They use AKI and CLC. Maybe also MON. But AFAIK, they don't use RON in the USA.

    90 AKI = 90 CLC = 95 RON
    93 AKI = 93 CLC = 98 RON

    Different units used in different parts of the world...

    100 Oct. racing fuel

    The proper and most economical way to use 100 octane gas in a 996/997 is to mix it at a ratio of 1:4 with 91 octane gas.

    I live in California, and have a Unocal station nearby that sells 100 octane fuel. As a matter of practice, I always fill-up the Porsche with 4 gal of 100, and 12 gal of 91.

    This gives a mixture of 95 Octane. 100 Octane Race gas sells for $5/gal and 91 Octane sells for $3 currently. That gives an average fill-up price of $3.50/gal.

    The car performs much better with this blend. It is smoother, faster, gets better fuel economy, and the engine is quieter.

    If you have access to 100 octane gas, I recommend blending it into your regular fuel fill-up.

    Re: 100 Oct. racing fuel

    100 octane fuel and 98 octane fuel got problems my Gallardo Engine.

    But i used 98 octane fuel for 3 years with my C4S and got no problem at all

    But i remember an article from a mag they tested 95 octane and 98 octane for BMW m5 E60 and it didnt show any significant power gains

    Re: use 100 Oct. racing fuel

    boardrider said:
    Is it true that racing fuel can contain lead that will destroy your catalytic converter?

    Race fuel comes in both leaded and unleaded varieties. Read the pump carefully, before you start filling the tank! Typically, 100-octane is of the unleaded variety, and the leaded race fuels are 110 and-up... I have to run 5 gallons of 110 leaded in with 15 gallons of 93 unleaded in my 1969 Boss 429 to keep it running happy with good ignition timing.

    Re: use 100 Oct. racing fuel

    I'll have to find those Unocal stations nearest me so check out the difference. Thanks for doing the mixture math. Sounds like a good ratio.


    Re: use 100 Oct. racing fuel

    I have a station nearby that sells all different octanes including 100. His higher higher octane fuels have lead and are used for racing and motorcycles. I always worry that his gas will get "stale" sitting in his tank since there isn't that much volume sold. So I use Shell 91 octane - highest avialable here in Denver and haven't had any issues. When I first moved here (before I found this station) I was using AvGas (101LL) in my motorcycle - finding it was much more difficult than the rural airports in Texas I used. Finally I found an airport with a self serve pump - worked just fine until I tried to fit the nozzel into the 5 gallon gas can. Seems like airplanes have much bigger oprnings.

    What octane is available in WA?

    I'm curious of the difference between WA and CA in order for you to feel the differene.

    And no, I'm not sure whether the ECU is programmed to adjust for octances above 93.

    Re: use 100 Oct. racing fuel

    easy_rider911 said:
    In the USA, they don't use RON. They use AKI and CLC. Maybe also MON. But AFAIK, they don't use RON in the USA.

    90 AKI = 90 CLC = 95 RON
    93 AKI = 93 CLC = 98 RON

    Different units used in different parts of the world...

    I thought that the anti-knock index was just another name for the ave of RON an MON? And the spread between RON and MON is typically around 10. So a gallon of US 93 might commonly have a 98 RON and 88 MON. But it could also have 97 & 89, respectively. All depends on components used to blend the gasoline.

    Re: use 100 Oct. racing fuel

    Different cultures, different units. Such as Imperial and Metric, right?

    Anyway Easy, this is the case with the RON, MON, AKI, etc.

    Re: use 100 Oct. racing fuel

    FYI, In general, most racing fuels are IMMENSELY more "stable" than current mandated mixes of 87-89-93 octane unleaded pump gas. In other words, the stuff can sit for months on-end with almost zero degradation, whereas 93 octane unleaded is sketchy to leave sit for more than a couple months. Racing fuel has super-duper shelf-life...



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