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Thread: Carb heat 912ULS

  1. #11
    Senior Member Dave S's Avatar
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    Oct 2008
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    St Paul, MN
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    1,833

    Default Re: Carb heat 912ULS

    Hi Paul,

    Your explanation makes it perfectly clear. Our Kitfox is an E-AB, not a LS; however, we do have the Rotax Airbox so your comments ring true to as to how how it would be hooked up. Currently we have an alternate air (no carb heat) with a screen over the tube stub on the airbox with the primary air intake plumbed to a flange on the side of the NACA vent - so the filter is in the air duct just ahead of the radiator.

    With some time on the KF, one of the things we observed with regard to the airbox is the rubber carb flanges have no wear or cracks....I replaced them @ the 5 year recommended time - but, I feel that I replaced perfectly good parts as the only way to tell the old from the new is the old ones smelled like gasoline and the new ones did not

    Thanks for the info - I do like the carb heat setup you have compared to the somewhat complicated earlier version. Think I need to talk to John McB. when I get the time.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  2. #12
    Senior Member Dusty's Avatar
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    Dec 2012
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    Christchurch, New Zealand
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    378

    Default Re: Carb heat 912ULS

    Here is some photos of a home grown carb heat system that is simple and works well
    Attached Images Attached Images

  3. #13

    Join Date
    Nov 2018
    Location
    Woodinville, WA
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    10

    Default Re: Carb heat 912ULS

    Quote Originally Posted by Dave S View Post
    Rainbird,

    Overall, it seems that people have little trouble with the Bing 64s and carb icing.
    Well, there is this one....https://aviation-safety.net/wikibase/wiki.php?id=138373

  4. #14

    Join Date
    Nov 2017
    Location
    Valrico, FL
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    55

    Default Re: Carb heat 912ULS

    I have had carb icing with two different 912s powered birds, once a Europa that was bad enough to require an emergency landing and once in a Rans S-6.


    My 4 will have a carb heat system.
    James T
    Valrico, FL

  5. #15
    Senior Member Esser's Avatar
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    Jul 2011
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    Edmonton, AB
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    2,048

    Default Re: Carb heat 912ULS

    You don't have trouble with carb ice until you do. You can buy a water jacket style that has a valve on it so it's not always on. Lots of hot water on a Rotax.
    ------------------
    Josh Esser
    Flying SS7
    Rotax 914iS
    AirMaster Prop

    Edmonton, AB, CWL3

  6. #16

    Join Date
    Jan 2010
    Location
    scotland
    Posts
    33

    Default Re: Carb heat 912ULS

    I have the carb heat box that came with the kit hot air from around exhaust re directed to carbs the old fashioned way.
    Last year I fitted a carb temp. Probe and oh boy was amazed at how quickly I get carb ice. Before the temp probe I would wait for the manifold pressure to drop, then when carb heat was applied the engine ran rough and appeared too be over rich, however I now know it was severe carb ice, what I do now is as soon as the needle on the gauge enters the yellow area I apply carb heat and no rough running . So those who believe the Rotax 912ul doesn’t suffer from carb ice because the carbs are in warm area of the cowling are going too get a shock
    Bam engine stop!
    There are several ideas out there , electric/ water jacket and what I have .
    The electric does pull a fair amperage,so be careful you don’t exceed the generator limit.
    The water system obviously only works when the water is hot you can’t switch it on or off so whether that effects the performance of the carb would be interesting to know.
    Stay safe

  7. #17
    Senior Member jiott's Avatar
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    Jun 2010
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    Portland, OR
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    Default Re: Carb heat 912ULS

    The water system carb heat suppliers say it does not affect engine performance and can be left on all the time. It only heats the carb intake body to prevent ice forming, but does not measurably heat the intake air which would affect air density/performance. Sounds like the simplest best system to me if you think you need it.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  8. #18
    Senior Member Dusty's Avatar
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    Dec 2012
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    Christchurch, New Zealand
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    378

    Default Re: Carb heat 912ULS

    I did some trials a while ago by clamping off the water supply to the carb heat blocks I had made.If there was a difference in performance it wasn't obvious.

  9. #19

    Join Date
    Nov 2017
    Location
    Valrico, FL
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    55

    Default Re: Carb heat 912ULS

    Quote Originally Posted by jiott View Post
    The water system carb heat suppliers say it does not affect engine performance and can be left on all the time. It only heats the carb intake body to prevent ice forming, but does not measurably heat the intake air which would affect air density/performance. Sounds like the simplest best system to me if you think you need it.
    This was the kit I had mounted in the Europa I flew

    http://skydrive.co.uk/proddetail.asp?prod=CH-912-3

    Left it on at all times and it didn't hurt performance in a measurable way.
    James T
    Valrico, FL

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