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Thread: Engine Help??

  1. #1

    Engine Help??

    So im currently planning/building a zenith 701. I have spent hours researching and discussing engine options with the few resources i have. Im down to The Rotax 912 S, Vikings new Honda Based engine and the UL 260. ANy comments or advice would much apreciated. For those who arent aware the Zenith is a STOL all metal 2 seater with engines from 80 to 100 HP recomendations.
    To invent an airplane is nothing. To build one is something. To fly is everything.
    Otto Lilienthal

  2. #2
    EAA StaffEAA Staff / Moderator Charlie Becker's Avatar
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    You may have already considered this but probably 90%+ of 701s are being powered by the Rotax 912 so from an ease of installation, troubleshooting and just general support standpoint, the Rotax would be the clear winner. Of the three, it is also the only one that has been approved by the FAA for use in standard category aircraft so it has been thoroughly tested (I realize you might not purchase their FAA approved model but the engine is basically the same). If you plan to fly the 701 off the beaten path, which if you're building a 701 seems likely, then it seems the Rotax also has the advantage of a proven record of performance. The other two engines seem like solid concepts and I hope can mature to where all the things I just said about the Rotax would apply to them as well. We need more engine choices at the 100hp level.
    Sonex flight testing complete. Building a Super Cub clone, check it out at www.facebook.com/piratecub

  3. #3
    Thanks for the input kinda what I guessed but was hoping one of you experts would help me save some money
    To invent an airplane is nothing. To build one is something. To fly is everything.
    Otto Lilienthal

  4. #4
    Aaron Novak's Avatar
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    Looks like the Viking is a honda without a balancer, I would personally avoid that at all costs. Inline 4 engines have a second order vibration parallel to the cylinder axis, without the balancers this vibration wreaks havoc on anything bolted to the engine like starters, injectors, coils etc.

  5. #5
    Thanks Aaron that is something i had not considered about the viking.
    To invent an airplane is nothing. To build one is something. To fly is everything.
    Otto Lilienthal

  6. #6

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    Revmaster has an interesting purpose built engine, new, 80-85 hp for under 8 grand. Probably buy two for what a Rotex costs.

    Ed

  7. #7

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    Viking

    Quote Originally Posted by Thomas Hayden View Post
    Thanks Aaron that is something i had not considered about the viking.
    You'd want to check specifically with Viking about this. They have done extensive work with this engine - it's not just 'bolt it on and call it an airplane engine' engineering. For one thing, they only recommend a particular 3 blade prop, and as I understand it, that is because there is little or no vibration when used. Check it out - don't just take my word or the word of an engineer, possibly, who is recounting a general theory about in-line 4's without checking on the specific engine. On Zenith's page, you'll see the the principal guy involved with Viking will be at Mexico demonstrating and explaining his engines. I doubt Zenith would give a tacit approval to an engine that would vibrate parts off.

    Happy flyin',

    jaksno

  8. #8

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    Quote Originally Posted by Ed Jeffko View Post
    Revmaster has an interesting purpose built engine, new, 80-85 hp for under 8 grand. Probably buy two for what a Rotex costs.

    Ed
    If you consider a VW conversion, also look at the Great Planes engines. Some very good features for aviation use. They have a direct drive that requires a wood prop, and a gear reduction. The gear reduction allows use of a longer adjustable prop, and is rated at 105HP I think; but you can deal with that by an RPM limit on the operating limitations. Much less than the Rotax, and no burp.

  9. #9
    Another potential option is the "new" Thunder Aviation "Thunder Chief" of 80hp. The line of engines was previously offered by Motavia as the UltraTec. The new owner of the engine line has apparently done some refinement of the product and has recently re-released the latter version. He also has a turbo'd version of the Thunder Chief which has been dyno'd at 107hp. I believe that the 80hp verson is around $10,500 as a complete package while the 107hp is around $13,000 (don't quote me!). They have a website that you can google.

    Good luck with your hunt.

  10. #10

    harmonic imbalance

    Quote Originally Posted by Aaron Novak View Post
    Looks like the Viking is a honda without a balancer, I would personally avoid that at all costs. Inline 4 engines have a second order vibration parallel to the cylinder axis, without the balancers this vibration wreaks havoc on anything bolted to the engine like starters, injectors, coils etc.
    I think what He is talking about is a harmonic imbalance. I don't think You would have that with the Viking engine or they wouldn't be selling them. If You check out their website You can tell they have extensive experience in aircraft engines. I had a automotive turbo-suburu EA-82 that had a 25lb flywheel which I removed and used an aluminum flywheel at 4lbs. Once in awhile at lowest idle is when I got harmonic imbalance. Oh it will shake like crazy. So I adjusted the idle up from 700 to 900rpm and never got it. I am sure they don't get that with the Viking. I figure it like this, (My opinion only) An automotive engine is alot more reliable than any certifyed aircraft engine because millions more have been spent on designing them. I feel certain that the Viking is a very smooth engine. It is my 1st choice for the CH 650 B Zodiac I am getting ready to build.

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