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  1. #1
    Stockrxp's Avatar
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    leaded or unleaded race fuel?

    what is best in these engines any why? What are most running? looked at ethanol but at my location too hard to get and still to new for me. thanks


  2. #2
    I thought that leaded fuel is bad for the O2 sensor?

  3. #3
    Bob 1tommygunner1927's Avatar
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    Quote Originally Posted by aklim View Post
    I thought that leaded fuel is bad for the O2 sensor?
    It is!

  4. #4
    Autism Speaks. Its Time To Listen gOt BoOsT's Avatar
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    ive ran both 100 unleaded and 110 leaded. everyone said leaded is bad for your o2, but i never had an issue...its an urban legend.

  5. #5
    Quote Originally Posted by gOt BoOsT View Post
    ive ran both 100 unleaded and 110 leaded. everyone said leaded is bad for your o2, but i never had an issue...its an urban legend.
    Are you sure about that? They do say it won't kill your sensor immediately but it will drastically shorten the life

    http://www.knfilters.com/airfuelmonitors.htm

    The oxygen sensor in your K&N Air/Fuel Monitor assembly is not compatible with leaded fuels or any fuel additive containing lead. Leaded fuel will contaminate the oxygen sensor causing it to deliver a false reading. The Monitor can, however, be used to momentarily test an engine burning leaded fuel. Simply install the sensor - re-calibrate the fuel delivery system to deliver the desired air/fuel ratio - then remove the sensor to avoid prolonged exposure. This short term exposure will extend the useful life of the sensor when testing an engine burning leaded fuel, but eventually it will become contaminated. Once contaminated, the sensor must be replaced to restore the accuracy of your instrument. Additionally, since there is no efficient way to test the sensor, there is no way to determine the level of contamination. Therefore, we recommend periodically comparing a used sensor to a new one.
    Other products that will contaminate or clog the sensor are:
    • Gas/oil mixture • Injector or carburetor cleaners contain lead additives
    • Octane boosters containing lead • Other “secret potions”.

    Edit: From my automotive experience, O2 sensors do not just suddenly die usually. Most likely they degrade over time and become "lazy". In which case, you probably wouldn't notice a problem until it failed completely or get past a certain point where the ECM is smart enough to realize something is wrong. Your contaminated sensor would be getting slower and slower as far as reporting back the AFR.

  6. #6
    R88ory RXP's Avatar
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    Quote Originally Posted by gOt BoOsT View Post
    ive ran both 100 unleaded and 110 leaded. everyone said leaded is bad for your o2, but i never had an issue...its an urban legend.
    Put it this way, given the choice the o2 sensor would prefere not to be run with leaded fuels, but then they dont really like water cooled exhaust gasses either sooo...

    They wont last as long but then we are unlikely to see good life due to steam damage.

    R88

  7. #7
    Autism Speaks. Its Time To Listen gOt BoOsT's Avatar
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    Quote Originally Posted by aklim View Post
    Are you sure about that? They do say it won't kill your sensor immediately but it will drastically shorten the life

    http://www.knfilters.com/airfuelmonitors.htm

    The oxygen sensor in your K&N Air/Fuel Monitor assembly is not compatible with leaded fuels or any fuel additive containing lead. Leaded fuel will contaminate the oxygen sensor causing it to deliver a false reading. The Monitor can, however, be used to momentarily test an engine burning leaded fuel. Simply install the sensor - re-calibrate the fuel delivery system to deliver the desired air/fuel ratio - then remove the sensor to avoid prolonged exposure. This short term exposure will extend the useful life of the sensor when testing an engine burning leaded fuel, but eventually it will become contaminated. Once contaminated, the sensor must be replaced to restore the accuracy of your instrument. Additionally, since there is no efficient way to test the sensor, there is no way to determine the level of contamination. Therefore, we recommend periodically comparing a used sensor to a new one.
    Other products that will contaminate or clog the sensor are:
    • Gas/oil mixture • Injector or carburetor cleaners contain lead additives
    • Octane boosters containing lead • Other “secret potions”.

    Edit: From my automotive experience, O2 sensors do not just suddenly die usually. Most likely they degrade over time and become "lazy". In which case, you probably wouldn't notice a problem until it failed completely or get past a certain point where the ECM is smart enough to realize something is wrong. Your contaminated sensor would be getting slower and slower as far as reporting back the AFR.
    will it shorten the life expectancy of the sensor? sure. by how much? who knows. i think its really luck of the draw...i replaced an o2 sensor in my truck that sees only unleaded pump gas, but ran leaded fuel in my evo without any issues. so imho they can and will fail at some point anyway.

    Quote Originally Posted by R88ory RXP View Post
    Put it this way, given the choice the o2 sensor would prefere not to be run with leaded fuels, but then they dont really like water cooled exhaust gasses either sooo...

    They wont last as long but then we are unlikely to see good life due to steam damage.

    R88
    well put!

  8. #8
    Quote Originally Posted by R88ory RXP View Post
    Put it this way, given the choice the o2 sensor would prefere not to be run with leaded fuels, but then they dont really like water cooled exhaust gasses either sooo...

    They wont last as long but then we are unlikely to see good life due to steam damage.

    R88
    Question. Where is the sensor? In cars, it is pretty close to the heads. If so, wouldn't it be upstream of the water cooled exhaust gasses and wouldn't it also be designed to work with exhaust gasses that do have water since water is a byproduct of the combustion process?

  9. #9
    Quote Originally Posted by gOt BoOsT View Post
    will it shorten the life expectancy of the sensor? sure. by how much? who knows. i think its really luck of the draw...i replaced an o2 sensor in my truck that sees only unleaded pump gas, but ran leaded fuel in my evo without any issues. so imho they can and will fail at some point anyway.
    True but being that O2 sensors were designed with the idea that leaded fuels would NOT be a part of it and manufacturers do not agree with having lead in the fuel, I would certainly say that it is an issue that can degrade the sensor. Many performance shops I talk to also recommend that if I run race fuel, I make sure there is no lead in it, I am kinda leery of what it can do. When someone says "without issue" I wonder whether it is that they don't see the issue because no test was done or whether there is really no issue. For all we know, you run well but your sensor is somewhat lazy already. In any case, with my luck, if there were 10000 tickets and I bought 9999 of them, I probably will not win so I am leery of trusting myself to the luck of the draw.

  10. #10
    R88ory RXP's Avatar
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    Quote Originally Posted by aklim View Post
    Question. Where is the sensor? In cars, it is pretty close to the heads. If so, wouldn't it be upstream of the water cooled exhaust gasses and wouldn't it also be designed to work with exhaust gasses that do have water since water is a byproduct of the combustion process?
    Yes your right it is up stream of the water cooled section of exhaust, but when you shut the motor off steam from that area travels through out the whole exhasut system, that causes condensation inside the sensor which damages them. Your also right that modern exhaust systems produce alot of H2o but where the sensors are is normally very hot which keeps the sensors dry. That being said you will never see the levels of condesation in a car exhaust that we see in our setup.

    R88

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