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Thread: Non-standard Engines for Kitfoxes

  1. #11
    Senior Member Rodney's Avatar
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    Default Re: Non-standard Engines for Kitfoxes

    I upgraded my 912ULS with Hal Stockton who offers a very high quality big bore kit.

    Several folks on the forum have also upgraded their engines and I have never heard a bad word about Jay (his partner) or Hal. They are just the best and stand behind their products.

    My engine is now rated at 114 Hp continuous. When you consider that a 912ULS is really a 95 HP continuous engine, it's a pretty substantial upgrade. And, you can really tell the difference.

    I think Hal also has a cam now that adds a little more HP, but you have to split the case to install it.

    My 114 engine was new cylinders and new pistons. They have more cooling fins on them and are really high quality. Basically, bolt on more HP.

    If you decide to go with the Rotax and want a little more HP, you might consider getting an upgrade from Hal.

    Regards
    Rodney

  2. #12
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    Default Re: Non-standard Engines for Kitfoxes

    Quote Originally Posted by genie View Post
    From what I understand the standard engines for Kitfoxes are the Rotax four-cylinder four-strokes, the Rotec, different Lycomings and Continentals, the Titan and the Jabiru 3300. If one chooses one of these engines then I presume that the necessary parts, such as engine mounts and cowlings, are easily available. I was wondering whether it would be about as easy/difficult to install instead an engine by D-Motor or ULPower or an automotive derived engine like a Corvair or a VW derived engine or an engine by Aero Momentum, by Firewall Forward (CAM) or by Viking, or, if available, by a Subaru derived engine.
    The Kitfox website currently shows a FWF kit for one ULPower installation.

    As for the Viking, I've seen one on the front of a Zenith 701. It looked like a really clean installation and he was happy with it. I think the biggest issue with the Viking is the reputation of the person selling the kit. I don't have any personal experience so I can't say one way or the other, but it is enough to cause me to pause. Looking forward to reading the Kitplanes article though.

    As for the Rotax engines? I've spent at least 20 years not being a fan of them but at this point I have to admit that they are not only here to stay but the statistics show they are every bit as reliable as the Continental and Lycoming engines. Some form of 912 is still on my short list, but probably in a somewhat hopped up form. If 100hp is adequate but 130hp is available it bears a close look.

    By the way those Continental and Lycoming engines are 1930's technology, not 50's and 60's. Unlike most people who love to disparage those old engines, I love them and appreciate them.

    Speaking of 1930's technology, I've got a couple hundred hours flying behind radial engines. I'll go as far as to say that for piston engines between 350hp and 2300hp there has never been anything better than what those geniuses did back then.

  3. #13
    Super Moderator Av8r3400's Avatar
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    Default Re: Non-standard Engines for Kitfoxes

    Quote Originally Posted by genie View Post
    Thanks to all for your comments.

    As for a Viking engine, I discussed this with homebuilder friends. They all dis-endorse the Viking engines as they say that they are made by the same people who used to provide modified Subaru engines for aircraft.

    It seems that the consensus is to go for a Rotax engine. I can see three issues with this:

    1) Such an engine is usually rather expensive, at least compared to some alternatives.

    2) I have heard of reliability issues with Rotaxes as they can fail. They are highly stressed for aircraft engines as they produce more than 1 HP per cubic inch, and in some cases 1.2 HP per cubic inch.

    3) Most important: I heard of many Rotax engines being stolen from their aircraft. As they are so good thieves take them. I would like to be able to sleep with peace of mind at nights and not worry about my Rotax engine being stolen.

    By the Numbers:

    1) Comparing a NEW Rotax 912 to a NEW Continental or Lycoming you will find the Rotax very affordable. I can list several people that have purchased low time used engines that are flying them today for less than $7500. Affordable 912 engines are out there, you just need to look for them. By the time they land on Barnstormers they are already sold.
    2) Reliability issues with Rotax are easily put into two categories: Owner induced problems and incompetent Mechanic induced. In both cases it is most often people trying to "Fix" something that isn't broken.
    3) This is an overblown rarity.

    If you enjoy the build and the experimentation of Experimental Aircraft, choose your own crazy engine and enjoy it! If you are more interested in flying, go with an engine that is supported by your Kit manufacturer and has some following among builders. This will give you the best chance of success.

    As to Viking, the day Jan Eggenfellner starts paying back the money he stole from all of his Subaru customers, I will take him seriously. Until then, I'm not interested.
    Av8r3400
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  4. #14
    Senior Member aviator79's Avatar
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    Default Re: Non-standard Engines for Kitfoxes

    HP/cubic inch isn't actually a very good indicator of engine reliability. Because Rotaxes run at much higher RPM, you could say that they are spreading that stress over more cycles. Brake Mean Effective Pressure (BMEP) is more closely correlated to engine reliability. As it turns out, it's just some constant times TORQUE/cubic inch. Here are some BMEPs:
    Conti O-200 - 147 psi
    Lycosaur IO-360 - 147 psi
    Rotax 912ULS - 165 psi

    Now, you might say, surely making the engine turn faster induces some stress too, and you'd be right. Mean Piston Speed is also correlated to engine reliability and longevity. However, because Rotax engines have a shorter stroke, the penalty isn't what you might expect:
    Conti 0-200 - 1778 ft/min
    Lycosaur IO-360 - 1967 ft/min
    Rotax 912ULS - 2320 ft/min

    In both cases, you'll see that the Rotax does run a little "harder", but not as dramatically as the HP/ci numbers would make you believe. The Rotax is also a comparatively more modern liquid cooled engine, and really has established a good record of reliability if they are maintained like Rotax engines and not like Lycontinentals. They are well-designed engines purpose-built for airplanes. They aren't inexpensive, but there are multiple sources for parts across the globe, and an enormous wealth of community technical support available. There is a reason they are the de facto standard for Kitfoxes, and pretty much the entire light sport market.
    --Brian
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  5. #15
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    Default Re: Non-standard Engines for Kitfoxes

    I will say I was seriously considering the Viking 130. I was willing to overlook the previous issues Jan had with his Subaru legacy. The customer service was awesome at being quick to respond and answer any and all my questions. What drove me away was Jan himself, daily digging himself into a hole on the Facebook pages. I get it alot of people are going to troll and what not but alot was him just saying generic, fluff. I don"t want to have to defend my powerplant at every fly in. It would become tiring very quickly. I met up with a fella in Anchorage with one on a Zenith, loves the engine however say he's constantly fighting with Jan about changes and upgrades that don't make sense. It seems he's DOES has a pretty awesome product but is not a Subject matter expert. Or, if he is just doesn't portray himself as such. Viking is off the table for me.

  6. #16

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    Default Re: Non-standard Engines for Kitfoxes

    I would like to thank everybody for your replies. I found them all very interesting. The above one provided me with very useful information about BMEPs and piston speeds of the most widespread light aircraft engines.

    My main priority is flying and not the build and experimentation of experimental aircraft. Therefore should I get as far as building a Kitfox I will choose a standard engine: a Rotax, a Continental or a Lycoming. If it is one of the last two I would never get it brand new as it does not pay to do so. One with 1500 hours or even 2000 hours would be perfectly well suited for me. I will keep away from Viking and Rotec engines.

    I love the looks and sound of Rotec engines. but due to their weight and drag penalties and reputation for inadequate customer support by this company I do not think it would be a suitable choice for me. Of course I love it if others get such beautiful engines so people who have the courage are welcome for my sake to get one of these or a Viking engine.

    In my opinion a diesel engine would be well suited for touring aircraft. But as no such engine is available this option would be for those who enjoy the build and experimentation process. The Continental ex-Thielert is not sold to homebuilders and I believe that few if any are available second hand. The Delta Hawk is very expensive. I heard some people have adapted automotive diesel engines for use in aircraft. Good luck to those who try.

    As long as we are on this subject: those who really enjoy experimenting with aircraft and engines could consider a Vija engine. It comes from France and is based on Suzuki engines and is cooled by oil and air. The trouble is that the company which produces it has closed. thus it must be difficult to find one and product support is non-existent. For further information see: https://vija-engines.wixsite.com/vija-en

  7. #17
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    Default Re: Non-standard Engines for Kitfoxes

    Interesting. I would recognize that motor anywhere. Hands down fastest motorcycle I've ever owned, and I've never owned a slow motorcycle.

  8. #18
    joecool's Avatar
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    Default Re: Non-standard Engines for Kitfoxes

    When choosing an engine for your Kitfox consider all things referenced in this thread. Plus one more thing, torque. Torque is what turns your prop. I personally purchased a D-MOTOR for the torque. Yes it was a little expensive
    but I don't have to worry about a redrive for the prop at annual time. We are working on it a little at a time(once a week) to get it installed on my Kitfox 2. You can see the pics on my profile.
    Oh, and one more thing Happy Mothers Day to all moms today!

  9. #19
    Senior Member 109JB's Avatar
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    Default Re: Non-standard Engines for Kitfoxes

    One thing that I didn't see mentioned is part availability. I like to see new engines come to the market, but when actually choosing one for my airplane I want to know that parts will be available. The Rotax, Continental, and Lycoming, are established and parts are readily available albeit not necessarily the cheapest. I want to know I can get parts if needed. Even the auto based engines like the Viking have gearboxes that can fail. If they are still around and still making the parts for your gearbox all is good. What if they aren't. I've been an EAA member for almost 40 years and the engine manufacturer's come around all the time and they also go away almost as fast. Lots of cool ideas have come down the pipe, but it wouldn't be so cool when your engine needs a part and the manufacturer isn't around anymore. Just something to consider.
    John Brannen
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  10. #20
    Senior Member jiott's Avatar
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    Default Re: Non-standard Engines for Kitfoxes

    I noticed the comment on torque:"it is what turns your prop". Yes that's true, but torque without adequate HP is useless. HP is what turns your prop at the speed required because it is a combination of torque and rpm. Some folks get hung up on engine torque but its only half the equation. Its POWER that you really need, especially in an aircraft engine where you never lug it down near zero speed. My torque wrench can generate all the torque I need to turn my prop, but my arms don't have nearly the power necessary to do it at 2000 rpm.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

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