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Thread: Zipper Big Bore

  1. #11
    Senior Member Esser's Avatar
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    Default Re: Zipper Big Bore

    To quote Scott Noble:

    “'THIS IS HOW A ROTAX 912 ULS(Now Injected Sport) IS SUPPOSED TO OPERATE' My main goal for this installation was to get a smooth running engine. I couldn't be more happy with the results. This engine runs very smooth throuout the RPM range. With the ULS dual carbs I couldn't sync the carbs perfectly throughout the full RPM range. There was always a little rough spot around 2700 RPM and various other vibration issues. I can only imagine a smooth engine will help this engine last. An added benifit was a bit more HP and better fuel burn. At this point I'm think I gained about 4 mph in cruise and gains in fuel burn as well. I will update this post as I continue testing.”

    For me and the Rotax 914 the EFI set up is lighter, smoother, less fuel burn or more power. In fact I no longer have to worry about my manifold pressure being higher than my boost pressure and if I wanted to I could run over boost and increase my power to 125hp with no other mods. No more cold start problems and no more hot start problems.

    The US military in a nutshell used the same EFI boards I have for the predator drones.

    Not for everyone I suppose.
    ------------------
    Josh Esser
    Flying SS7
    Rotax 914iS
    AirMaster Prop

    Edmonton, AB, CWL3

  2. #12
    Senior Member HighWing's Avatar
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    Default Re: Zipper Big Bore

    Quote Originally Posted by jrevens View Post
    ... As has been pointed out before, the increased cost will most likely never be made up by the slightly better fuel economy, by the average owner, even after many years...
    There many reasons that one airplane might be more fuel efficient than another. Fuel efficiency goes beyond engine efficiency and aerodynamic cleanness. In the early 1980s. I started working at United Airlines on the ramp. Baggage, Mail and Galley changeout were what I did in the beginning. This changed to fueling, then as a SOR in the Control Center. I sat in front of a computer calculating loads on outbound flights. My ultimate responsibility was to create an accurate Manifest that was then ACARS transmitted to the pilot as he taxied for takeoff. This gave him the load and the location of that load so he (she) could make the final judgement as to where everything fit relative to maximum takeoff weight and CG location. It was while working here, I learned about the parameters that were developed during the Arab Fuel Embargo, ten years or so years earlier. Since any airplane is most aerodynamically efficient when the CG is near the aft CG, that was determined to be the ideal. Passengers were spread through the cabin to achieve that goal. Baggage, freight and mail were also loaded accordingly. This was to minimize fuel burn during the flight using the scarce fuel more efficiently.

    Now to Kitfox. When I finished my first Model IV in 1998, I was disappointed that my empty CG was a bit aft. This was due to the 8 lbs. or so that I added to the empennage when adding full airfoil shapes to both vertical and horizontal tail surfaces and gap seals – plus the electric elevator trim. As a result, I was forced to placard the baggage sack at 20 lb. Max vs. the 40 lbs. standard. Then the Ah! Ha! moment. On our first, Flight of 6, trip to the Idaho back country we stopped in Winnemucca, Nevada for fuel. All were curious as to fuel use during the three hour flight from Rancho Murietta. Number one was a Rans S-6 that burned almost 14 gallons. The others – Model IVs - varied between 9 and 11 gallons. I burned 7.6 gallons which included my 30 minute flight from O61.

    Now things are a bit different. A new Model IV, completed in 2016. Not wanting to have to limit luggage after doing even more to the empennage than the first time, I moved the engine forward using a home brew engine mount. I calculated 2.5 inches further forward which, in practice, proved to be too much. Now with a CG closer to the forward limit, I find that the airplane is much draggier than the first one. I don’t have fuel use data on this one, but the airspeeds are not impressive compared to the first one. From my experience we could install the most fuel efficient engine there is and still buy more fuel at that three hour fuel stop than the other guys flying with a regular old Rotax mounted in a lighter, better balanced more aerodynamic airplane.
    Lowell Fitt
    Goodyear, AZ


    My You Tube Channel

  3. #13
    Senior Member jrevens's Avatar
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    Default Re: Zipper Big Bore

    Quote Originally Posted by Esser View Post
    ...

    For me and the Rotax 914 the EFI set up is lighter, smoother, less fuel burn or more power. In fact I no longer have to worry about my manifold pressure being higher than my boost pressure and if I wanted to I could run over boost and increase my power to 125hp with no other mods. No more cold start problems and no more hot start problems...
    Josh,

    I’m not sure if this is part of Scott Nobles’ quote or not, since there are no quotation marks, but I hope all of this is true for you when you finally get yours running. I’m surprised that it would be lighter than a stock 914. The 912is is a heavier installation than a 912uls, but that may be like comparing apples to oranges. I think I’d personally be a little leary of running over boost, also. I hope it proves to be a very reliable engine for Scott, and you too! Fuel injection is great, but the options right now are just a little out of my comfort zone. Guess I’m not much of a true experimenter, but I admire the efforts of you “trail breakers”!
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  4. #14
    Guy Buchanan's Avatar
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    Default Re: Zipper Big Bore

    Well I read a post last week that said an iS Kitfox travelling across country averaged 125mph at 3.2gph. Now my 100uls IV only can manage 5.6 gph at 120mph so I'd say the injected engine is worth about $12/hour in 100LL. So the re-pay might be worth it over a engine's lifetime. ($12/hr is $24k over 2000 hours.)
    Guy Buchanan
    San Diego, CA
    Deceased K-IV 1200 / 912uls / 70" Warp 3cs

    gebuchanan@cox.net

  5. #15
    Senior Member AirFox's Avatar
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    Default Re: Zipper Big Bore

    Hay John, the Edge Performance EFI installed on the 912ULS is lighter than the Rotax 912IS. On the 912IS the Auxillary control box, Fuel pumps etc add to the weight. If I remember correctly the 912IS is aproximately 20 lb heavier than the ULS. When I weighed my EFI prior to installation it was about 2 lb lighter than the stuff I removed. I removed the carbs, fuel pump and all the tubing.

    As far as performance I am very happy. Almost 10 more HP way better fuel burn and runs very smooth. I have almost 100 hours on the EFI now and I am very happy with it.

    My fuel burn in the past 100 hours averages 3.4 gph. Doug also installed the EFI on his engine at the same time. Doug(Floog on Teamkitfox) just did a trip across the Cascades at 50% power and got 2.6gph at over 100mph. My 10.8 hour trip to the High Sierra Fly in I got 3.4gph flying at 60%HP averaging 108mph. The Rotax engine has been very reliable and I expect with the smooth running EFI installation I'll get even more reliability. My fuel burn range prior to EFI on the Rotax 912ULS was between 4.12 and 5.4. Compare that range to 3.04 and 3.9 with EFI installed.

    The return on my EFI investment will be covered within the TBO just in fuel cost. I paid about $5500 for the EFI kit. Go to BadAssPowersports for the N American rep if your interested. Jason is a good guy to work with on the install.

    Your going to be very happy with your engine Josh. Good luck getting it flying.

    Scott
    Scott Noble
    Kitfox SS7

  6. #16
    Senior Member Esser's Avatar
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    Default Re: Zipper Big Bore

    My earlier post was supposed to say I don’t have to worry about my manifold pressure being higher than my fuel pressure like s traditional 914 set up.

    Im not going to have this make extra power but it is an option for people looking for that.

    I honestly think that the success of these after market systems were so good it caused Rotax to come out with the 912iS and 915. A warranty would be nice though!
    ------------------
    Josh Esser
    Flying SS7
    Rotax 914iS
    AirMaster Prop

    Edmonton, AB, CWL3

  7. #17
    Senior Member av8rps's Avatar
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    Default Re: Zipper Big Bore

    Going by memory here, but I think the same people (Hacmann?) that made kits to convert rotax 582 carbs to include a mixture adjustment, do the same for the 912 bing carbs. Obviously the fuel injection units are running much leaner, more efficient fuel settings compared to how most of us have our carbs set up. So with a little effort and cost I'm sure we could get our carbureted 912's to run close to the same efficiency.

    Just my two cents...

  8. #18
    Super Moderator Av8r3400's Avatar
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    Default Re: Zipper Big Bore

    Av8r3400
    Kitfox Model IV
    The Mangy Fox
    912UL 105hp Zipper
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  9. #19
    Senior Member av8rps's Avatar
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    Default Re: Zipper Big Bore

    Thanks Larry. I just read that link and thought I would forward the one for the 4 stroke details for those that want to read more

    http://www.greenskyadventures.com/bi...an_4stroke.htm

    For only $198 it's kind of a no brainer.

    Is anyone here on the forum using the Hacman mixture control option on their 912?

  10. #20
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    Default Re: Zipper Big Bore

    Before I converted my 912 to EFI, I ran the HACMAN for a couple of years. One of the best investments I made. (At that time, it was around $150.) I saved so much on fuel, I was able to afford EFI. Well almost I used it from the moment I took off but especially above 6,000ft. Eliminated fouled plugs caused by overly rich mixtures, too.

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