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Fuel venting/dripping out air filter/intakes 912S

in General Tech Discussion 10 years ago

  • Re: Fuel venting/dripping out air filter/intakes 912S

    by » 9 years ago

    Hi Paul,

    Is it possibly the place you have the carb vent tubes causing a pressure unbalance?

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: Fuel venting/dripping out air filter/intakes 912S

    by » 9 years ago

    There are over 40 similar installations (no air boxes) with the vent tubes exactly the same as mine were operating fine, but the two at higher altitude are spitting fuel out the air filters (not the vent tubes). After all the trouble shooting it must be altitude related. I am beginning to think this may be why Rotax added an air box to fix this problem.

    My other high altitude operator is going to try an altitude leaner that is supposed to be rotax approved so he will try that. I am running about 1250 F EGT and I know we can lean it out up to 1600 F with the rotax limit at 1616. Someone said this can increase RPM by 300 (which I find hard to believe) but we will see. The iS I am flying automatically leans it out to quite high EGT.
      
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  • Re: Fuel venting/dripping out air filter/intakes 912S

    by » 9 years ago

    I wouldn't lean it out to run too high in the EGT temps. Usually in the 1400's is a fairly good place to be.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report

  • Re: Fuel venting/dripping out air filter/intakes 912S

    by » 9 years ago

    OK 1400 will be our target. Will let you know what happens.
      
    Report

  • Re: Fuel venting/dripping out air filter/intakes 912S

    by » 9 years ago

    Hi Paul,

    Good luck and let us know the results.


    1400F up to 1500F is pretty normal at normal cruise rpms depending on your current atmospheric conditions.
    We try not to be overly cold or overly hot. I good plug and fuel burn is what we are hoping to achieve. That said if you are at low altitudes and around 1440F EGT and then fly to 10K in altitude the EGT's are going down and nothing you can do at that moment and nothing to worry about. Other temps will be affected too like coolant/CHT and oil temp. It's perfectly okay to have temp changes with altitude, but we try to find the balance point. For the average user Rotax has the engine setup pretty well. Another item that can really affect temps is the prop pitch. As an example you wouldn't want to fly with EGT's in the 1100F range all the time or right up by 1600F all the time. Summer verses winter conditions will play a part in temps too.

    As far as the engine air intake you are always better off using the outside cool air for better engine performance verses separate air filters inside the engine compartment using only the hot air in the engine compartment. Will the average user notice the difference? Probably not.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report
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