912ULS, or 912IS or?

I am probably going to order a Kitfox 7 SS I saw a video the person building said to get the ULS over the IS due to ease on maintenance, I considered the 915 but don't want to go that expensive. ALso considered the STi but going SS due to cost.

I would go ULS. Then down the road you can add Edge upgrades.

That is certainly one way to do it without the upfront cost of the iS.. Funny, I bought an iS because of what I believed the answer to the "less maint." position was, fuel injection. There are a number of people flying trouble free with the iS. Ross flew his across his continent of Australia. At least twice!. I know, if that ECU starts giving you problems, its gonna cost ya. Besides, be honest. If the after market fuel injection system is what you are contemplating, then you already agree its a wise way to start if you can afford it. IMHO.

It is true that the 912iS is a more complicated installation in some ways and requires the use of a computer interface to properly diagnose problems, and an electronic display to monitor engine sensors. I have 280 hrs. on my 912iS and about 4000 hrs, flying aircraft with the usual general aviation engines. If given a selection I would take the 912is every time. Some of the early 912iS engines had a gearbox vibration problem, including mine, but the issue was resolved with a modified lubrication system. Due to the computer control of the engine, cold weather starting is a non event. No carb, no primer, no mixture, no mags, two alternators, two fuel pumps, two injectors in each cyl, two identical computers with each one able to take over all function in the event of one computer failure, electronic audio and visual warning system of engine problems, and cabin heat available from engine head cooling system. Plus. uses standard automotive sparkplugs at about $2.50 each. Recommended fuel is mogas but can use 100LL. Weight is about 120 pounds. When I purchased mine the cost was about $2500 more than the carb version 912. So the up side is having a latest state of the art modern engine and the down side is costs more.

See if I can revive this discussion a bit with this question:

Totally acknowledge that the 912iS isn't much more expensive than a ULS. And my current truck does not have carb's. And that fuel injection can pay for itself in fuel given enough time. and that modern engine monitoring is awesome.

BUT a 912iS IS a lot more expensive than a 912 UL ---- and with a 912 UL I can send that thing off to Zipper and have them work magic, take that thing to 125 hp. I'm still not injected at that point --- but i have 125 hp cooking. and i have about the same amount of $ invested as a 912iS at that point. Personally I'm thinking I might rather have the extra 25 hp than injection at a 22k price tag? and THEN you sure could go to edge and throw EFI on there. and yep, now you're at 27k (i think? kind of tough to convert those KR to us dollars?). BUT you are at 125 hp, and you're injected, and you're well under the cost of a 914. and you're significantly lighter than a 914. and if you want the fuel savings? a hacman controller adds mixture control for under $300.

my point in drawing this out (yes i have a spreadsheet... yes i am trying to solve this myself right now) is that the reverse of all this is NOT true. you can NOT start with a 912iS and upgrade to 125 hp. there just isn't a way to get there. I think. Can someone check me on that? that's my sticky wicket with the 912iS -- it seems un-up-gradable. i don't see anyone selling larger jugs, i don't see any turbo kits out there for it ------ it seems like once you go 912iS then that's where you're at. you get a great engine, modern monitoring, great fuel, easy starts, ALL that .... but if you want more than 100 horses ... well ...

So right this second i am considering starting w/ a 912UL and never putting that on my plane, just sending it off to Zipper.

Where I am stuck in the complexity of the upgrade is how to do engine monitoring. I'm not sure how long it would take me to add EFI, and even if/when you do, now which product is going to do the engine monitoring for you? would that product also work in your "pre-efi" stage? You also have to accept that you will never have the turn key, fully integrated engine monitoring that the digital out of the box 912iS offers (and it's direct integration into so many modern electronics). So. if I can get my head around THAT ... well that's what I'll probably do.

Thoughts?

......and, of course, as soon as you add you Edge conversions, big pots or whatever you just waved goodbye to any Rotax warranties. Maybe not a consideration for some but if I've paid that much for a new engine I want to keep the new engine warranty.

Hawkertech,

Each of us ends up with a decision we figure serves us best.

I can't compare our choice of the ULS with the other 900 series Rotax engines; however, we came to understand the S7 was engineered around the engine and matched the aircraft very well - that proved to be true. The S7 with the ULS performs all around far better than any aircraft I have have flown before. We did pop for the induction airbox. The ULS is derated to 95 HP if the airbox is not used. My observations are that most LS and EAB aircraft with ULS engines do not use the airbox.

I feel that maintenance is pretty straight forward on the ULS; and, I am very comfortable with carburetors while I have concerns about getting repairs done on electronics out in the Boondocks. The periodic rubber replacement on any 900 series is going to be essentially the same. We did replace the old Ducati CDI modules last summer and I would like to think the current module versions correct the faults of the old. Other than that - no surprises.

My engineering pals tell me that simplicity is the price of reliability. While none of this stuff is stone butt simple, there is less complexity with the ULS version.

Another thought, if cost and convenience is a concern, is let someone else beta test the 1.0 versions (newest/latest/greatest) and wait till there is adequate history to best understand reliability/cost. The old early adopters vs late adopters theory. We are not all rich enough to take a chance.

It seems if something is going to take a dump - it's almost always stuff that has electrons and semiconductors.

No regrets here on the ULS. So far I haven't even received any software upgrade notices on the carburetors:rolleyes:

I am sure you will be happy with whatever engine version you decide on. I think it is hard to go wrong on the ULS.

Oh - almost forgot a quote I saw related to expeditions taken by people on assignment with National Geographic - the guidance was - get a vehicle for the expedition that was manufactured prior to 1985 so you have some hope of getting it fixed out in the boondocks.

Thanks all still considering a purchase, and maybe thinking tri gear since I am trigear trained and dont have tail wheel training, and since Texas doesn't have many back country options. Also thinking it may be easier for my DW to get into. just need to find someone near Dallas that has one to try and see if the DW can get in.

Hawkertech, any further along with the deliberations?

I'm still watching this with great interest, I like the idea of the 912ULS if only to get the EP912is upgrades at a pace I can afford.

I am pretty sure I am going 912ULS, for some simplicity in maintenance, and cost. The only thing that concerns me is the chance for carb Ice, but what I have been reading it is not very prevalent in these engines.

I talked with Hal Stockman because I am leaning towards the 912is and was thinking more hp someday and he said the zipper big bore kits will go right on the 912is . Nothing else has to be done cause the computer compensates the fuel need via the oxygen sensor . So no problem getting more hp according to him. This is just info, I do not push either engine to anyone but no way am I having carbs when I can have fuel injection. JmO

my point in drawing this out (yes i have a spreadsheet... yes i am trying to solve this myself right now) is that the reverse of all this is NOT true. you can NOT start with a 912iS and upgrade to 125 hp. there just isn't a way to get there. I think. Can someone check me on that? that's my sticky wicket with the 912iS -- it seems un-up-gradable. i don't see anyone selling larger jugs, i don't see any turbo kits out there for it ------ it seems like once you go 912iS then that's where you're at. you get a great engine, modern monitoring, great fuel, easy starts, ALL that .... but if you want more than 100 horses ... well ...


Thoughts?[/QUOTE]

I have a Flight Design CTLS with a 912ULS. Works just fine and no complaints.
However, I'm building an S7 SS and will be putting in a 915iS, Airmaster prop.
There is no substitute for power, the fuel injection is simplicity and it has the Rotax warranty.
Sure, there may be some teething pains but Rotax has been pretty darn good about backing up their product.(from my A&P who is the guy for Rotax in my area)
It is more money for the fuel injection and larger engine but I just know that if I didn't use that engine I would always regret it.