I stopped to see Greg this weekend. He sold the engine to a guy building some single seat hi-po hovercraft. Or maybe it was an airboat.....

Greg Swingle........wherever you are: go Big Bore, forget that turbo and all the associated BS that come with it, just saying

Is it fair to ask here what the installed cost on the 104hp version is? I'm far from ready for an engine but will probably be keeping an eye out for a clean 912UL in future months. I'm all trained up on the basics of working on these things but labor is seldom the biggest part of this sort of conversion. Best to have the guy who's done a ton of them knock it out in a hurry than me messing with it and wondering. I like the idea of the 104hp because you don't need the slipper clutch with it and it will bolt up to a lot of 912ULs without modification.

$4500.00, that was with the pistons ringed and fitted in the jugs, and I was lucky enough to have Hal install it for free. Coming up on 30 hrs now and the difference is much more then the numbers relate, only 5 more horses, some say . Well, the stock 912S dyno's at 95 or 94, not 100. So on the face of it a good 10% power improvement. More torque is harder to quantify, all I know is it goes UP a lot better, with a lot less throttle. Runs cooler and is lighter also. Smoother too! Just got through putting around locally at reduced power settings, 65 to 70 MPH, with a little higher speeds, and a very accurate fuel burned check showed my burn rate for 1.3 hrs. was 3.2 GPH. One full power max climb showed 1,000+ fpm (cool day, just me but full fuel plus usual junk in back, at 6500'), my old engine would have been 700, maybe, at most. The Hackman Leaner is working as advertised! My overall burn rate has gone DOWN, now that I am using it, while I enjoy all the other improvements. Other then the aforementioned $4500.00, once you get past that, it is all good.

Mister701,
I am in the process of ordering the kit and this is the reply I recieved from Jay, the gentleman handling sales. I am hoping to get a check out for the kit before weeks end.

"1484 ZIPPER HT 105HP $4200.00
1484 ZIPPER HP 114HP. $4300.00
Quick Kit (Pistons installed into cylinders). Includes case sealant and New seals. $300.00

Recomend for your own installation you buy from us. More expensive elsewhere.
Circlip installation tool $60.00
8 New Push Rod Seals. $24.00
You'll need a tube of case sealant
from your local cycle shop.
Some quality break in oil.
About six hours.
Now YOU'RE ready to go out and feel the gradification of your insallitation, and FEEL THE ZIP."

Thanks WW. It sure seems like a no brainer if the right 912UL shows up.

courierguy wrote:Just passed 20 hours now since the Big Bore conversion. I now have the Hackman leaner installed also. On a flight to Afton this morning at 9K with an old ultralight flying buddy from out of town I was playing around with it. Though my EIS fuel flow indicator is still in the calibration phase, it was obvious that leaning is a great way to reduce the fuel burn Also a way to increase the EGT temps, I have some richer/larger jets on the way, as now I can have the best of both worlds: a rich mixture when desired for cooling while still being able to lean her out once way up and cruising. I am without CHT probes for my new EIS right now, and had pulled the steam gauge CHT, plus all the other round engine gauges the day before as part of my current weight saving mania) though they should arrive tomorrow, so I didn't mess with the mixture and the EGT temps too much, mostly just a test run, and breakfast of course. The next few hours should see the jetting optimized for the new larger displacement Big Bore Rotax/Hackman leaner/GRT EIS combo , in the meantime I'm flying about every day. Right about the time the dust settles on all these changes, my 78" Prince Prop will arrive, to stir things up some more.

Now that I have (for the first time) a digital representation of my EGT temps, I found that my Swiss Muffler seems to accidentally be acting as a tuned exhaust of sorts. Removing it anyway resulted in a immediate reduction of EGT's by 35 to 40 degrees. Having had it for 1300 hours, I have decided I have "been there, done that, scratched that itch, etc." and at 7 lbs including the mounting hardware, it is now regulated to the "good idea, fun while it lasted, but let's move on" wall. A little nosier, sure, but still damn quiet, I'm good at finding solutions to non existent problems. Plus, being on a weight reduction kick, losing 7 lbs for NO money is irresistible!

As expected, driving to Elko after flying there a few days before really sucked, especially hauling a wide and somewhat fragile load, this 10' wide by 20 long solar array. A good picture of Mr. Big Bore, Hal, right after we first took his 3 KW solar grid tie system for a test run

CG,

Sorry I missed you when you powered up Hal. Sounds like a great system you've got. Hal told me about the hookup. I had to laugh as that is so Hal!

Mike

48 hours TT now, and as it heats up outside the much lower CHT temps are very much appreciated. As is the faster climb to altitude, where it is of course cooler, so a win/win.

The next part of the upgrade is a new prop, Catto is shipping me a 78" x 46" TODAY I am stoked, as it is one particularly tweaked for the big tired Roberts Gear S-7S, or at least based on the current performance #'s as I reported to him in some detail a while back. He takes the numbers and somehow turns them into a prop, I don't really care how he does it, but does it he does! I mentioned that I do a fair bit of XC in addition to off airport, so hopefully I get something that has a good cruise, I don't want to be stuck in first gear in other words. If my cruise stays the same I'll be happy, I'm pretty sure it's a given, going from the 70" 3 blade Kiev (adjustable pitch so a compromise in efficiency along the entire blade length) to a fully optimized along the entire length 78" club that my take off performance, always more then adequate, will get even better. Christmas came early this year!

This past weekend Hal, my son Jake and I just installed a new High Performance Cam in the 1622, Now more testing.

Any updates?

I've got some cash burning a hole in my pocket. Can't decide if I want to take on the 1622 or do high hp 1484 for the ease of conversion.

courier guy wrote: RE CATTO: I'm pretty sure it's a given, going from the 70" 3 blade Kiev (adjustable pitch so a compromise in efficiency along the entire blade length) to a fully optimized along the entire length 78" club that my take off performance, always more then adequate, will get even better. Christmas came early this year!

This is important in a lot of ways. When taking my LSRM training we spent a number of hours on prop design. These adjustable props really aren't a very good idea for the reason CG hints at here. You can actually set up a warp drive (for instance) so that the mid blade area is pulling like mad but the tips are PUSHING BACK! The other issue of course is mass moment of inertia. The 100hp Rotax is well known to eat up sprag clutches in about 600 hours. They go a lot longer with a lighter weight prop. The difficulty and expense is in finding the right fixed pitch prop for your weight and speed and expectations. We'll be watching eagerly for your results on the Catto.

About 80 hrs on the 1622 and about 20 hrs with new Cam, I am still doing testing and fine tuning the carb / Jet settings, all is going very well and the New Cam is much smoother than a stock Rotax cam I am able to get it to idle down in the 800's smooth and no gearbox chatter. Not suggesting running it there but it lets you know just how well the cam is working. I will be doing some additional testing later this week and seeing if the Cam has any improvement in High Altitude.

I am patiently awaiting Tm's report on the new prop also.
On a side note, I pulled off two of my cylinders last night and the one's on the plane looked real bad. The buildup on the pistons was some of the worst I have seen. Some of the build up may be from the original builder using 100LL and then the oil blow by built up on top of that.
I am not sure if the pistons/cylinders were broken in or of it is a combinaation of the rings and valve stem seal. Either way, lots of carbon and sludge on the top of the piston and on the cylinder head.
I was hoping this Big Bore kit was was going to be an easy swap but now I will be ordering new Valve guide seals and may as well replace the hoses and other incidentals while I have it apart. Looks like my plane will be sitting for awhile until parts arrive.

My first Catto prop arrived and I flew with it for a couple hours, and took it off. Sounds bad but I was told to expect it to be a protoype and that might happen. It climbed a bit better, cruised slower and went over redline at WOT. Sounded great though and taxied (uphill) on much less throttle. After I gave Craig the inflight performance numbers, he told me to hang it on the wall and he'll send another more fine tuned one out when he gets back from Oshkosh. He seems to enjoy the challenge of fine tuning a prop/engine/airframe combo, telling me he now knew exactly what changes to make in the design, and seem eager to get back on it The man loves his work! It's all black magic to me.

So back on with the Kiev it was for the last 20 some hours, until yesterday, when my new Prince 78" prop arrived. Off with the Kiev and I ran up the P-tipped monster (it's kind of sinister looking, a real bad ass looking black carbon blade, looks like something Batman would fly with) last night but no flight yet due to WX. It also sound great, and different from the Catto, idle down to 1200 (where my throttle stops are) was smooth, that's pretty huge for a Rotax, so good engine AND prop.

The Kiev is still the light weight champ: 7 lbs. 15 oz Catto 8 lbs. 2 oz. Prince 9 lb 12 oz. But, remember the Catto and Prince are sweeping about 25% more area, so in effect they are very close to the Kiev depending on how you work the numbers.

I have 82.2 hrs on the Zipper conversion now, and other then a brief moment of excitement due to my maintenance tech failing to replace the radiator cap after a fluid check (air cooled guys can laugh now) it continues to perform great. The good thing now is that like the airline pilot landing at the wrong airport, I am probably the most unlikely to ever have the cap go missing again, ain't going to happen, ever, lesson learned.

I'm burning regular mo-gas BTW, much of it E10 when not at home. I continue to moniter my fuel burn real close, still having fun with my new fuel flow system. I back it up by very accurate at home re-fills, and several times i have noticed something interesting. For instance, this last weekend I flew up to and around Kalispell Mt., jumped a bunch of ranges, flew down some, ground skimmed some, got up to 9K+, the usual mix. 4.32 gph in 5.8 hrs. The return flight I backed off just a hair on the throttle, and got a bit more attentive with the HackMan mixture control, and upon a carefully measured re-fill once home came in at 3.2 gph. Either I am making a pretty large error in my computing, or else there are some large benefits to backing off that throttle a bit and really using that mixture control, or maybe a little of all three? MORE flying will determine this

Either I am making a pretty large error in my computing, or else there are some large benefits to backing off that throttle a bit and really using that mixture control, or maybe a little of all three? MORE flying will determine this

Or, the ethanol with it's built in oxygen is making your petroleum based hydrogen and carbon molecules burn more efficiently.

I flew with the Prince for 2.8 hrs today, and wow, it is nice! The sound......, it's very different, much lower pitched and overall quieter then even the quiet Kiev. This was verified by another S-7 pilot I flew over at various throttle settings, and by taking my headset off. I guess this is in part due to the P tips, whatever it is I really like it.

I did my usual, fired it up in front of the hangar, put the parking brake lightly on to hold it back while idling,then put the headset on and the other numerous things we do to get ready. Then I gave it a little throttle to taxi uphill to my turnaround and do a final pre flight check. Like the Catto it took little throttle to ascend this grade. Then I noticed the parking brake was still on That told me that at full throttle it would probably have enough thrust to get me airborne, to say the least.

My WOT top speed was 107, real good for a fat tired Roberts gear mod equipped S-7, with the Kiev it was 102. ROC at 9'000' was 700' fpm, solid and sustained. Lower down, 5 to 6, it was 900 to 1100. Again, better then the Kiev or the Warp, or the first Catto. Smooth too. 65 mph was 2.2 gph fuel burn and a bit over 4K rpm, and super quiet, a great sightseeing mode.

BUT, I was only able to get 5000 static runup, and even at 107 mph it was only 5620. I need an additional 200 rpm on both ends to be within the best operating range of the 912, and I confirmed this with Hal and others. So close, very close, and though I was loath to let it slip through my fingers, I took it off and sent it back to Lonnie so he can shave a bit off the tips (or however he does it) to let it rev up that last 200 rpm. It should be a monster prop then I put a note in the box, a followup to my earlier email, stating the request for more rpm, along with a demand that he not change the sound it makes, that is perfect

Right at 90hrs on the 1622 BigBore and 30hrs on the new Cam. The engine is improved with the new cam, performance is improved ever so slightly but an improvement, Cam allows for better performance of the Carbs, final settings came it at 180 Main Jets with the needle clip settings second from the bottom, This at or near sea level of cruise EGT's in mid 1400's and Hard climb temps at low 1400's. Above 3500' leaning is noticeable with great improvement above 6-7000'. Have only taken it to 13,500 with the new Cam with Rpm still able to reach 5600 using leaning and climb rate still at or slightly better than 500' min.

Now we will continue to check for any wear as we continue testing but my opinion at this point is it will be as good or better than Stock.

Interesting John, 101 hrs here now, and I have to thank you again for bringing the HackMan Leaner to my attention, it puts (or leaves) money in my pocket every time I fly. However, the other day I launched off a 8600' ridge near my place, and then shut her down for the glide home (done this before) and at about 800 agl went to re-start and ....didn't. Not yet wanting to see if I can land my uphill strip dead stick (I'm sure I can actually, just don't NEED to) I started thinking, and realized I was all leaned out for the above 9K I was at earlier, so I cranked it in full rich and the re-start was normal. Actually, it probably would have started anyway, it just wasn't instant like usual, you have to be smarter then the Leaner.

Once my second Catto or my second Prince prop arrives (the second should be optimized, the first from both them was to establish a base line), one or maybe both (?) of these props should be the final ingredient to really getting the most out of my particular Big Bore conversion for my bird.

One thing different about the Big Bore, is the oil consumption. I was used to sometimes going 70 hrs between changes and adding NO oil, with the stock setup. I'd use some, but I would start off high, and by the time it got to the lower part of the usable zone of the dipstick, it was time to change it anyway.I got a little lackadaisical about checking the oil, as it didn't seem to use any. My Big Bore does, but I am comfortable with that, here's why: if I understood Hall correctly, the rings are "set up loose", until they reach the higher rpm's involved in racing, then they seal tighter, as designed. The benefit at the lower rpm's I am running at is LESS FRICTION, this may be part of why my CHT's are so much lower then before. Hal said that going to Oshkosh and back he really got on it, 5700 rpm there and back, and he noticed his oil reduction went down! I have kept careful track of my consumption, and also have noticed the same thing, if I'm puttting around local, in the mid 4500's, I may use more oil then cruising at 5200' or so.

My average overall oil use as of 100 hours seems to be 300 ml every 16 hrs. So roughly a qt. (or a liter I guess) every 50 hrs, (or incredibly low in Lycoming/Continental terms) which is when I change the oil anyway. Actually less use in practice, as that last time I almost need to add oil, I just drain it, so about 600 ml. every 50 hrs. I never used to take any oil with me on a XC, didn't need it so why pack it? Now I take a half bottle and check the level every 10 or 12 hours. I consider the top of the flat part of the dip stick FULL, and about 1/4" above the bottom of the flat part NEEDS OIL. No need to get all anal about it, somewhere in that range is close enough.
It has been very consistent and I very comfortable with this new development as compared to my stock 912. I gained more horsepower and torque, smoother running, quicker throttle response, much cooler CHT's, and lastly about 3 less lbs in weight. Oh yeah, in my case anyway, the ability to burn regular mo gas more then pays for the oil: 50 hrs =1qt., call it 9 bucks. 50 hrs. times 4 GPH (at most) = 200 gallons, and it is around a 30 cent per gallon difference in these parts, so I save 60 bucks in fuel costs versus 9 bucks in oil costs, fair enough

courierguy wrote:My first Catto prop arrived and I flew with it for a couple hours, and took it off. Sounds bad but I was told to expect it to be a protoype and that might happen. It climbed a bit better, cruised slower and went over redline at WOT. Sounded great though and taxied (uphill) on much less throttle. After I gave Craig the inflight performance numbers, he told me to hang it on the wall and he'll send another more fine tuned one out when he gets back from Oshkosh. He seems to enjoy the challenge of fine tuning a prop/engine/airframe combo, telling me he now knew exactly what changes to make in the design, and seem eager to get back on it The man loves his work! It's all black magic to me.

Courierguy,

Just curious as to the length and pitch of the Catto prop you tried. I have a big bore engine coming from Ronnie Smith for plane I'm currently building and went ahead and ordered a Catto prop for it because I was scared of lead times (was not a problem, got prop in a month). I was told by a couple of people that should know to get a 82" x 38 pitch. I didn't speak with Craig but with his daughter and she seemed to agree this would be the correct combination. The plane I'm building is a Just Aircraft SuperStol and I believe it is the same prop currently being used on Troy Woodlands plane but I do need to check.

Take Care,
John Cooley

John,
Different planes and different engines so not sure what good the info will do you but I am working with 78" x 46" props from both Prince and Catto. They both independently came up with this size after I supplied them the performance #'s I was getting with the KIEV prop. 78" is about as big as I want to go BTW as come winter the small tires and the wheel skis go on, and flat light, deep powder, drifts, getting stuck, and who knows what else can all conspire to make a larger then that prop become a snow blower!