I flew to Elko yesterday and Hal Stockman installed a set of his pistons and cylinders, called the ZIPPER conversion. More power, smoother, more torque, only regular fuel needed, not premium, cool better due to the billet CNC cylinders being denser then the cast Rotax material, with additional cooling fins, and 3 lbs LIGHTER. I can idle smoothly now down to 1200 rpm, smoother in flight also. After a short test flight and a wait on the weather, I flew it home later that day. Initial impressions are very positive, 300 more rpm static shows it's working as planned. I plan to fly the heck out it the next few days to get it broke in. Hitting my usual haunts will highlight the performance changes, I can't wait. I've known Hal for some years and he really knows his stuff when it comes to anything mechanical. A lengthy series of posts by a SoCal Kitfox pilot on their forum was very helpful in getting me up to speed on the subject also. My stock engine was flying great, with zero problems, my plan is to pay for the conversion by flying more, the fuel savings is my excuse, the extra power, less weight, smoothness and better cooling are the icing on the cake. No real need for the extra power but I got it anyway

The contact person is Wayne Flemington 951-255-9144. a long time Rotax dealer. Hal is busy, really busy, Wayne is the guy to bug with questions, the teamkitfox forum has the thread by a guy who goes by the moniker "Big John", he is doing a great job on reporting his findings on the mod, very informative.

Very nice Tom! Glad to see Hal is still ticking. I just realized I've never seen him in anything except those coveralls.

What is the price for this kit? Getting 100hp with regular gas sounds very appealing. You were talking a few months ago about the Catto prop tests. Is there any news update on that?

Edit: Kit offered on Barnstormers
http://www.barnstormers.com/classified_ ... ROTAX.html

Still waiting on Catto, I ordered a 78" Prince prop in the meantime, and it is 3 weeks out, Either prop is supposed to be lighter then even the Kiev. The mods that increase performance while losing weight, get me every time! I've been eyeballing my steam gauge panel and getting weights on items like the GRT Mini, that can do everything and more the steam gauges do (as long as I have power that is) for 18 oz. A careful and simple panel redo could save me a few more pounds, while offering more capability, damn it

What I found interesting is that the 912S dyno'd out at 93 to 95 hp., the Zipper at 105. That additional torque is the most interesting thing, you can really feel it as it climbs easier without lugging down, a subtle change in how it feels. Several times I needed a bit more altitude to clear some ranges I was crossing, and a very slight pull on the stick got me that altitude without hurting the cruise speed. The first time I thought I was lucky to be getting some lift, right when I needed it, after a few times I realized the additional low end torque of the engine was making itself felt. It's like when I drive the mountain I live on, a 1,000' climb to my place, I hit the bottom curves with max speed when driving my small displacement Toyotas, I keep the rpm's up. With the Dodge Cummins 1 ton, it doesn't matter so much, all that torque gets me up, the rpm's don't matter so much. Heading out this AM for my first local flying

Any idea what the highest compression ratio could be? Would be neat to run high % of ethanol with a CR way up there for high efficiency. Just think of the power with all that oxygen already in the liquid fuel.

I am flight testing the BigBore Zipper 1622 for Hal and Wayne for the last Two months and am very impressed, I have flown with the 1484 114hp which is 11-1 compression and the 1484 105hp which is 9.7-1 compression, The 1622 initially was 115 hp we changed the jetting and now are at 185 jets vs stock jets of 157 the HP should be close to 118-120' The 1622 is a 10.5-1 compression. The 1622 improved my climb by 400'+ and speed by 10mph. The next test will be to change the Cam, Since there is some interest here on the forum I will post the ongoing testing of the 1622 BigBore as we continue. We did find that down near sea level we even had to go to 165 jets on the 1484 105hp unit.

Very cool. Plated aluminum cylinders should last a long time, too. Motorcycle engines can get over 100K miles in that configuration easily.

Big John.....you're the guy to blame for me spending my hard earned dough on this conversion! Your recounting of the performance increase on the Kitfox forum, and my previous knowledge of how handy Hal is. THANKS!

I just flew local for the first time, and man oh man, it's like I'm in a thermal all the time or something. Much easier to ascertain the performance increase in familiar surroundings. The torque is the big deal, unlike before I can be in level flight and gently pull back the stick and start climbing and the revs don't drop, and the climb continues as the speed stays about the same! There really is no replacement for displacement. And being able to buy regular mo gas at Elko for the trip home was a kinky thrill. A bit over 5 hrs total time now.

Though I've been trying to keep working it hard during the break in period, 5400 rpm and up, today I was shooting landings on the ridgeline across the valley from my place so it was back to my usual lower throttle settings. Circling in the 40's, nose high, all the thing that lead to high cylinder temps. MUCH cooler running, the head temps now match my oil temps almost, rare to get over 200 degrees there. These sites below are both around 7200' to 7800', and this is the first time I've landed them this season, thus a lot of low speed circling to check for any changes, cooler running without a doubt. AND, it isn't even broken in yet

Tomorrow or the next day I'll be flying to Afton for breakfast. There are a series of 8K+ ridges I need to clear, not to mention the one right behind my house. I've been flying this route for 30 years, and am very familiar with it, so another good practical test of the 1484 conversion, with breakfast thrown in.

This site is just steep enough to not want to stop nose uphill, (a bitch to get going and turned around) and I run my tires low enough to not want to park sideways, and pointing downhill it is very iffy when you try and use the parking brake, and besides I already have pics of the plane parked there, once was enough, now I land it and I'm outa there. The touchdown site is right of the clump of brush, above the rocks of course. This is a ridge line between 2 valleys, and for the first time I was able to land it uphill, usually the morning breeze means a slight downhill landing, which is especially weird when about 95% of all my landings are uphill, good practice in airspeed control though. Easy to park also. The first time I landed here a few years ago, I ran into a fireman buddy who started in on me. It seems he was running the ridge line, and saw me land and knew it had to be me and tried to make it over before I blasted off, damn unfriendly to takeoff without saying hi he said It was real nice knowing I was packing 3 lbs less weight AND had more power for both these sites, and about a half dozen more similar ones but not as photogenic.

Courierguy

I found about 6hrs for good ring setting with some oil consumption after that oil consumption minimal 8 oz in the next 20hrs, some difference in that I am testing the 1622 conversion, I have had to settle in on 185 jets mostly due to near sea level flying, 175 or 180 would work if higher but I installed the Hackman leaning unit for dialing in at altitude. We are going to install a newly designed Cam next which should make a big improvement in the 1622 unit. I know Hal is also working with a company to produce a tuned exhaust.

Glad to have helped you spend your hard earned money, you won't be sorry.

Dammit I thought we were done spending on this project.

I've got one of the Hackman leaners on it's way. 25% or even 20% less fuel burn at altitude, that's a no brainer, I gotta have it. Right about now the Cont. and Lyc. guys are laughing their asses off: "being able to fine tune the mixture in flight, what will they think of next?"

I don't even have an EGT gauge, I wonder if I need one? Can I just bumble my way along without it, and figure it out as I go, or is an EGT gauge a must if using that manual mixture control? No fuel flow meter also...I can see all this leading to a 6.5" GRT Sport MFD, and if I do that I may as well upgrade to a carbon graphite cowl and shed some more weight. A slippery slope, my main criteria is that any changes weigh less, not more. Saving 20% in fuel in cruise is a huge weight savings, kinda.

gbflyer: I had a great run of over 1300 hours since completion without spending ANY extra dough (besides the VG's, a header tank, a ferry tank, the new large fuel tanks, the Airstreaks, the wheel skis, the Roberts Gear mod, and the Rage shock struts for the Roberts gear), I am trying to resist building a whole new plane, and I guess I have decided to just upgrade what I have. That way I can keep flying in the meantime, if I do it right. But no, you are never done!

Thanks cg.

I like the sounds of the Zipper mod. No way I would do the install myself though. The thought of tearing into that little Austrian jewel with little experience with them scares me silly. Maybe have to freight Hal up to Alaska along with the parts.

Hey cg

You will want to monitor the EGT's if your going to use a Hackman and I would recommend a fuel flow meter, Heck it's only more of that hard earned money you have been getting rid of.

I know what you mean gb. I visited with Hal yesterday afternoon. I thought I had a long flight for the install, but it's nothing compared to what you would have.

There was no single part part of the process that appeared difficult. Pretty much just unbolting things and then re-bolting. Reading the instructions (after the fact), they are accurate and clear. Hal used a home made wrist pin puller, just a piece of all thread and some spacers that gently pulled the pin when tightened. The snap ring comes out with a awl or ice pick, or other pointy tool. He also had a home made snap ring installer, don't know if that's required or just speeds things up, it was also simple. Common sense when re-installing everything: gradually tighten the bolts equally, then use a torque wrench. Then after initial run up and lunch (in our case) re-torque, check for leaks.

Having a helper with a background of mechanical work would be handy though not required. NO specific need of Rotax experience needed, maybe the torque value for the bolts but that's it. I really can't see it taking longer then an easy day. I too was very apprehensive, remember my plane was flying great when I arrived in Elko, an hour later I was grounded!

Got another hour in today is all, didn't go to Afton, but S-7 guru Joel Milloway's hangar. He was in the middle of something or else I would have offered to let him fly it, I did show him the 1200 rpm smooth idle and that blew his mind. I also got in the production line for one of his upright panel mods. Carbon graphite, and I won't need to mess with my windshield or boot cowl interface, this will just extend from there, a little different then he usually does it. I need this because as I suspected if I have the mixture control, I need the EGT gauge, and might as well have a fuel flow indicator and instead of cobbling them into my existing panel which is already "modified" enough, it's time to start over and ditch the steam gauges. I plan to track the weight difference (lighter is the goal).

Flying back the 30 miles to my place, another familiar route, it was again pretty obvious that things have changed for the better, performance in the past was very good, now it's gooder, and it's so effortless, no sense of hot rodding the engine or anything, the much cooler CHT's temps would seem to prove that out.

Hal and Wayne just got another shipment in if anyone is interested in a 1484 conversion.

Unfortunately I'm tapped out right now from the rebuild going on with my 2nd Kitfox IV. Maybe after the yellow one gets sold this kit may be in my future.

Big John wrote:Hal and Wayne just got another shipment in if anyone is interested in a 1484 conversion.

Well I sure had a long wait. I called Hal while out with the dog on morning patrol, so a bit after 8:00 AM, I confirmed I had decided on the 1484 conversion, and he responded with "I'll get the parts together and let you know". I didn't press him on when, I figured a week or two. 7:30 that evening of the same day, he calls back, and now it's a go! 8:00 PM the next day I land back at home with the finished product providing the motive power, pretty hard to beat a turn around like that.

I had it up to nearly 11K today, full throttle ROC was 5 to 600 fpm. Also did some extended 45 mph nose high circling at over 8K while eyeballing a new site, the lack of almost all CHT temp increase in this scenario is much appreciated, before I'd either have to rush my landing or get the nose down and speed up for a bit to cool things off, not anymore.

Thus far I took the 1622 to 18k and was still climbing at just under 300' min, Max CHT's we're at 204. These Conversions are Great.

This video compares takeoffs between a 1484cc BB at 11:1 compression and a turbocharged 912. Hal is flying the white S-7 with the Zipper BB conversion off the grass.