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coolant

in General Tech Discussion 10 years ago
Does anybody have any idea why Evans is now not allowed by Rotax. I cannot figure out what difference it would make, with reference to the new temperature probe location. I sure would like an explanation from Rotax.
Mike

  • Re: coolant

    by » 10 years ago

    Here is what I was told:
    It is allowed; You can still use Evans with the old style heads.

    Reason for not allowing Evans with the new heads:
    1) The heat transfer is worse with Evans.
    2) The new heads only measure the coolant temp, as Evans has less thermal heat transfer capacity it is possible in some installations (with poor airflow)to exceed the thermal capacity of the engine causing damage.
      
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  • Re: coolant

    by » 10 years ago

    Hi Michael,

    This is in line with what I have heard and personal experience.

    Michael,
    Nothing really wrong with Evans. It just has no water so the heat transfer is worse than with 50/50 and carries with it a 20-30 degree heat penalty over 50/50. Water coolant does a much better job of carrying away heat because it transfer heat much better and faster than waterless Evans. Evans was looked at originally because of some boil overs. 50/50 coolant boils down around 270F and Evans is around 370F. It may stop a boil over, but causes over heating in many applications. Better to figure out why someone is boiling over or over heating instead of using Evans.


    in cold country or in some fully open air engines Evans may not be too bad.

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

      
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  • Re: coolant

    by » 10 years ago

    Roger and Rob,
    Thanks for the info...now i understand the reason they require 50/50. Although i live in Alaska so it is possible that Evans would work just fine I think I'll stick with 50/50.
    regards
    Mike
      
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  • Re: coolant

    by » 10 years ago

    What a load of tosh!

    There is nothing wrong with Evans coolant. It has more good points than bad. It is better for the engine. It may run hotter in aircraft designs where there is a problem with cooling or radiators that are too small have been fitted.

    How can you say that a coolant is not recommended because the way the temperature is measured has changed. The temperature of the engine hasn't changed, just the way it is measured.
      
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  • Re: coolant

    by » 10 years ago

    Hi Mark,

    Rob isn't saying there is anything physically wrong with the coolant itself. Just the different types of engine installations make it a poorer choice over water based coolant at times.

    I don't think there is anything wrong with Evans nor do people think it's bad. I think part of the point was the old CHT was more a metal area temp verses an acutual in the coolant probe temp. There would be a few degrees difference.
    And like you said the only reason it didn't work for some was the cooling isn't as good for some and put them over temp. I think they were originally looking to help some with boil over issues, but Evans doesn't exchange heat as fast as a water based coolant. This is why fire departments use water. It's the best heat transfer and it's cheap to use.


    There are a few factors that make Evans work for some and not others.

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

      
    Report
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