912is / carb

[Flybyjim]

I have always flow behind a carb engine and I am almost ready to order my engine and firewall forward. For those of you who have gone this road before me and forget the difference in the cost why choose the 912is?

[jrevens]

I know that there is a lot of extra "stuff" needed for the 912is, Jim. It all takes up space in the engine compartment as well as behind the panel, probably. It is definitely a more complicated engine & install, and is a newer total design that will probably undergo more changes as field experience is accumulated. I would ask the question about how much of an installed weight difference there is between the two. We know the additional installed cost of the fuel injected engine, which will be mitigated somewhat by increased fuel economy. However, I believe that it would take many, many hours/years of operation to reach a break-even point with that additional cost. There are benefits in using fuel injection, of course. No carburetor ice (which is generally a non-issue with a Kitfox installation, but it can happen), perhaps smoother operation and no carburetor balancing needed. Those are just a few points that come to mind.

[DesertFox4]

I chose the 912 ULS 100 hp again for some of the reasons John mentioned. Weight, complexity, ease of install, familiarity with tuning and maintenance and a proven track record. Fuel economy was considered however I was more comfortable with the simplicity of the whole package.

Also I liked the option to be able to take it to Hal someday and have a big bore kit installed.;)

That being said, I've heard good comments from those that are flying behind the fuelie Rotax. Fuel economy is really good compared to the 912 ULS versions. They are amazing power plants.:)

[efwd]

I bought a 912is. Read back at all the issues balancing carbs and float issues etc etc. I dont want to deal with that. Damn, I hope this install isnt that complicated. Fuel efficiency is a plus too and I will own this thing long enough to recoup the cost difference. That is if I fly it as much as I hope too.
Eddie

[jrevens]

We just looked at a 912is installed by Eric Joern on his Kitfox project in Colorado Springs. It's a beautiful engine Eddie (his airplane is beautiful too!) ... I didn't mean to denigrate the engine at all... just trying to think of some pros & cons. I did get a good look at all the extra boxes and things that make it work and do it's magic. Eric commented that he was surprised at how involved the installation was. It's probably pretty straight forward though, and I'm sure it'll go good for you.

[colospace]

I was dead sure that I would get the 912iS..... until I started looking at numbers. I made some assumptions about fuel cost and projected fuel burn. It appeared to me that it would take me 1000hrs/10years to recoup the extra cost. Having owned a couple of British sports cars with SU and Stromberg carbs, I decided carb balancing would not be a major pain. For these reasons, as well as the thought of being near the bleeding edge of installation experience of a potentially more complex installation, as John mentioned, I decided to go with the 912ULS.

[jiott]

Regarding carb balancing, after once getting them really well balanced I have gone thru three 100 hour inspections without having to touch the balance. I hook up the gauges each time to check, but they seem to always be in good balance.

[jrevens]

I've heard similar stories from others, Jim. I think I'll be real happy with my 912ULS.

[Flybyjim]

Thank you all for your thoughts on this option. The fuel injection does bring with it more $$ and time for the installation and more glass on the panel. As much as I like the idea of glass I keep coming back to my past experiences with round gauges and the reference scan I am use to. I really like the Garmin G3X and I may go with this with the thought at re-sale time the next guy/gal may want some glass. I do not like my eyes inside the cockpit, I want to see the world and any objects coming my way asap. This is not to say those with glass don't look outside but my recent experiences with a couple fellow pilots who have installed glass spend way to much time looking inside and worrying about a few degree temp changes on the cylinder heads, their engines have been running just fine before they had all this info to look at. As with all choices in life what works for one may or may not be best for the next. I think I will go with what I know and stay with the Carbs, the extra savings can help pay for some instruments.
I hope to meet many of you this year at Oshkosh.

[neville]

I installed a 912iS on my SS7 in 2013. It weighs 20 lb more than the carb engine. The installation was straight forward as McB,s provided a complete set of instructions for the FWF kit including the engine. It does require an electronic engine monitoring system (EMU) . A stand alone unit runs +/- $5000. while a glass panel including EMU functions plus other features such as synthetic vision , angle of attack , and charts is also about $5500. Now that I have operated the A/C for 200 hr. I can see that the safety issue is much improved with angle of attack and syn vision. Remember the smoke problem at the 2015 flyin? With syn vision all those rocks high in the sky were no issue. And short field landings are a non event with AOA. Many fuel injected engines can be very difficult to restart a hot engine but with the computers starting the 912iS the aviator has to really do something bad to not start the engine. All the pilot has to do is perform the Rotax startup procedure including setting percent of throttle for outside air temp and the computers decide how much injection is required . It is true that the fuel system is a little more complicated in that more filtering is required. I agree that many pilots are spending to much time operating the glass panel instead of looking outside. My panel has features that I have not used yet because I don't have time.

[jeffbock]

Have the 912ULS and been flying it for 3 years and love the airplane. Engine runs good but at idle I do have roughness on right carb that is noticeable. Above the 3200RPM level it is quite smooth. Just balanced using the CarbMate device and it's right on the money. Any thoughts on where to start on the right carb vibration. it's been doing this ever since new so I have thought it may be a Rotax moment. JeffB

[Esser]

I'm late to the party but I have an aftermarket injection setup for my 914. More power, less fuel, smoother engine, no balancing of carbs, better cold weather starts, and the fact I can run over boost now if i wanted to is the reason I went that way.

[WWhunter]

Esser,
I think we may have discussed it before, but what aftermarket Fi setup do you have? Was it difficult to install and setup?

[AirFox]

Jeff have you checked to see if you have a heavy float. I had one of the 2 dot floats sink. It ran rough until past 3200 RPM then quite smooth like yours. Just fill your float bowl with fuel and see if the floats sink.

Good luck. Give me a call if you have a question.

Scott



Have the 912ULS and been flying it for 3 years and love the airplane. Engine runs good but at idle I do have roughness on right carb that is noticeable. Above the 3200RPM level it is quite smooth. Just balanced using the CarbMate device and it's right on the money. Any thoughts on where to start on the right carb vibration. it's been doing this ever since new so I have thought it may be a Rotax moment. JeffB