Rotax 912iS versus the 914 Turbo - Which One?

[Adam]

Happy New Year Everyone!

Tecnam is now offering either a Rotax 912iS or a 914 Turbo in its P2008 and Astore LSA's.   It got me thinking -  The 912iS is Fuel Injected, the 914 is turbocharged but is back to dual carbs.  Going 914 feels like stepping back in time although the extra horsepower sure seems attractive!   Toying with the idea of adding a second aircraft to my stable.  I have always been drawn to the fit and finish of Tecnam.  Having said that I chose FD 3 times in a row for some particular reason! 

[Duane Jefts]

Nice looking airplane.  I would stick with the 912i.  In a light sport it does all the work necessary at whatever altitude airport and density altitude operations plus it starts really easy, get's great fuel mileage for those long trips and has no instances of "rubber in the carbs".

[paul m]

Maybe the 915iS will be an option at some point unless its too heavy.  

[Ed Cesnalis]

I would prefer the 914 if I was you.  It can do what the 912 can't and you could really use it because you are surrounded by mountains.  

The 914's performance only gets better and better up high and the 912 falls off normally.  At altitudes needed for California cruising there's a 20kt difference.  Climbs to 12,000 will have a night and day difference as well.

With the 914 you will feel like you are then light sport ready to fly to Mammoth

With the 914 my CT would be 150+ kts top speed.  With the 912i my CT would be 127+ kts top speed.   Best speed for the 912i is at 7,500'DA  Best speed for the 914 is prolly 16,000'.

 

 

[Adam]

3 hours ago, paul m said:

Maybe the 915iS will be an option at some point unless its too heavy.  

That would be sweet!  Best of both worlds, fuel injected and turbo!

[FlyingMonkey]

912iS.  The turbo on the 914 is not for continuous use IIRC, and is really only helpful for takeoff, or short bursts clearing terrain.

[Ed Cesnalis]

20 minutes ago, FlyingMonkey said:

912iS.  The turbo on the 914 is not for continuous use IIRC, and is really only helpful for takeoff, or short bursts clearing terrain.

My best friend has one in his Europa.  We use continuously and can cruise near 200mph.

[ct9000]

37 minutes ago, FlyingMonkey said:

912iS.  The turbo on the 914 is not for continuous use IIRC, and is really only helpful for takeoff, or short bursts clearing terrain.

It is true that the 115 hp is available for five mins. but 100 hp continuous. When you get up a bit higher your 100 hp non turbo will be making probably about 60 hp but the turbo is still making sea level hp up to about 16000, after that it drops off a little. 

[Ed Cesnalis]

26 minutes ago, ct9000 said:

It is true that the 115 hp is available for five mins. but 100 hp continuous. When you get up a bit higher your 100 hp non turbo will be making probably about 60 hp but the turbo is still making sea level hp up to about 16000, after that it drops off a little. 

Think about it, it means a ~60% cruise power increase!  

[markmn]

Hi, Mark Gregor from Advanced Aircraft/Tecnam US here.

I hope you don't mind me responding but the post is referencing a Tecnam after all!

We end up discussing pros and cons of the Rotax engines regularly. All three Rotax engines are offered by Tecnam because we believe they are all good viable choices. It just depends on what you want. The 912ULS is a well proven engine at a low price. The 912is is the latest in technology, full fadec w automatic lean of peak operation below 97% power. Impressive but no more horsepower than the ULS and likely less in many conditions. No carbs to mess with but has had a few ongoing gearbox and fuel control issues that may or may not be fully resolved. Definitely much better than when it was first released though. 

The 914 is a mature design but the turbo can be additional maintenance if a few basic care rules are not followed. The last 914s we delivered had carb leaks at high manifold pressure settings. Was easily resolved by a good Tech but goes to show nothing is ever perfect. With that said and nearly 1500 hours divided between all three Rotax engines the 914 is nearly always my first choice to pull out of the hangar. I like the 914 because it is smoother, quieter and substantially more powerful! The first time I flew the P2008 with the 914 i was very surprised how much stronger it was. Really sets you back in the seat compared to the 912. Takeoff roll is substantially reduced. The 914 cruises at 35 inches manifold continuous. At this setting the 914 is making a lot more horsepower that a 912. 40 inches manifold or 115% power as Rotax calls it is limited to 5 minutes. When I hear negativity about the 914 it is nearly always from someone who has never flown behind one.

Disadvantages?  A $20,000 more than the ULS and $8,000 more than the 912is!

Mark Gregor

Gregorma@bevcomm.net

507-3279465

[Ed Cesnalis]

4 minutes ago, markmn said:

Hi, Mark Gregor from Advanced Aircraft/Tecnam US here.

I hope you don't mind me responding but the post is referencing a Tecnam after all!

We end up discussing pros and cons of the Rotax engines regularly. All three Rotax engines are offered by Tecnam because we believe they are all good viable choices. It just depends on what you want. The 912ULS is a well proven engine at a low price. The 912is is the latest in technology, full fadec w automatic lean of peak operation below 97% power. Impressive but no more horsepower than the ULS and likely less in many conditions. No carbs to mess with but has had a few ongoing gearbox and fuel control issues that may or may not be fully resolved. Definitely much better than when it was first released though. 

The 914 is a mature design but the turbo can be additional maintenance if a few basic care rules are not followed. The last 914s we delivered had carb leaks at high manifold pressure settings. Was easily resolved by a good Tech but goes to show nothing is ever perfect. With that said and nearly 1500 hours divided between all three Rotax engines the 914 is nearly always my first choice to pull out of the hangar. I like the 914 because it is smoother, quieter and substantially more powerful! The first time I flew the P2008 with the 914 i was very surprised how much stronger it was. Really sets you back in the seat compared to the 912. Takeoff roll is substantially reduced. The 914 cruises at 35 inches manifold continuous. At this setting the 914 is making a lot more horsepower that a 912. 40 inches manifold or 115% power as Rotax calls it is limited to 5 minutes. When I hear negativity about the 914 it is nearly always from someone who has never flown behind one.

Disadvantages?  A $20,000 more than the ULS and $8,000 more than the 912is!

Mark Gregor

Gregorma@bevcomm.net

507-3279465

That smooth power is such an upgrade that it becomes a different class of airplane, especially out west where that power is needed and useful for high percentage of flights.  Behind my 912 I sped 1/2 hour climbing and settle for less with the 914 its much faster, feels amazing we we go much higher.

Have had carb issues for sure.

[markmn]

Yes there will likely be some carb maintenance on the 912ULS and the 914 but overall we have seen less issues than on the 912is.  The 912is is the first full fadec aviation engine with auto lean of peak and it has been a challenge. I have full confidence Rotax will get it 100% but as of today I'm still more comfortable behind the carb engines. 

Mark

[FlyingMonkey]

2 hours ago, ct9000 said:

It is true that the 115 hp is available for five mins. but 100 hp continuous. When you get up a bit higher your 100 hp non turbo will be making probably about 60 hp but the turbo is still making sea level hp up to about 16000, after that it drops off a little. 

Got it, thanks for clarifying.  Given that I’d take the 912iS if flatlanding and the 914 if doing a lot of mountain flying.

[ct9000]

4 minutes ago, FlyingMonkey said:

Got it, thanks for clarifying.  Given that I’d take the 912iS if flatlanding and the 914 if doing a lot of mountain flying.

Also as has been mentioned the 914 is quieter and very smooth. I believe this is because of the slightly lower compression ratio but I could be wrong on that.

[Adam]

So perhaps the right answer is to add 2 more planes to my stable?  An Astore with 912iS and a P2008 with the 914 :-)

[Adam]

1 hour ago, markmn said:

Yes there will likely be some carb maintenance on the 912ULS and the 914 but overall we have seen less issues than on the 912is.  The 912is is the first full fadec aviation engine with auto lean of peak and it has been a challenge. I have full confidence Rotax will get it 100% but as of today I'm still more comfortable behind the carb engines. 

Mark

Mark - while I have you on the horn...  Talk to me about the Astore v p2008.  Which is your favorite (and why)?

[markmn]

Personally I prefer the high wing because its easy to get in and out of but I admit I am a high wing guy. The Astore is not hard to get in and out of but just not as easy as the 2008. The 2008 is a bit longer and larger than the Astore and thus handles turbulence and cross wind landings a bit better. Overall both the Astore and P2008 are just physically larger than other LSAs so there is not a lot of difference.

Although we occasionally see a pilot switch from high to low wing or vise versa it doesn't happen often. Both the P2008 and the Astore are great planes just like the Flight Design and because I like one better doesn't mean others will. I recommend getting a test flight in every aircraft you can!

Mark

[ODowneyEng]

I prefer a supercharger over a turbocharger anyday . Turbo exhaust failure makes for a great blow torch. I have seen some scary holes burned through fancy tight cowls. In my opinion as an engineer the supercharger is safer and for that reason even with the parasitic power draw. We have been conned into the cheap bolt on turbo extra power. Just my 5cents worth.

 

Keep the greasy side down

[ct9000]

1 hour ago, Odowneyeng said:

I prefer a supercharger over a turbocharger anyday . Turbo exhaust failure makes for a great blow torch. I have seen some scary holes burned through fancy tight cowls. In my opinion as an engineer the supercharger is safer and for that reason even with the parasitic power draw. We have been conned into the cheap bolt on turbo extra power. Just my 5cents worth.

 

Keep the greasy side down

Your need to keep the greasy side down may be 'cause you pushed the pistons into the sump with over boost at low engine speed.

 

[912iS Fanatic]

I’ve been flying a P2008 with the 912iS  for over 3 1/2 years out of CA, in the mountains.  The engine is by far the most reliable Rotax ever made.  Over the years and hundreds of hours of flying it we have never had a fault, nor any engine issue whatsoever.  The 912iS with the sport upgrade sips fuel (<3.5 gph), and maintains at least 110 KIAS through 12,000 MSL.  In our family we have also had two 912ULS powered planes, and one 914.  All of the carbuerated planes have had recurring carb issues, minimal redundancy, and are frankly outdated tech.  

When single lever constant speed (CS) props become available, hopefully late this year, only the iS engines will be eligible since they are full fadec engines, that means only the 912iS or 915iS.  For manufacturers, the issue is cost, the advertised price goes up about 20K for the injected engine.  The injected engines have/require among other things metal fuel lines, high pressure filters, and provide substantially more electrical power along with over 27 engine sensors and dual redundant Engine Control Units (ECU).  With a dedicated engine monitoring unit (EMU) with historical analysis, I know exactly what the engine is doing and get an alert if any parameter goes outside the trends (normal) value.  It’s far cheaper to get a carb’d engine, without ECU’s or an EMU, but having both, I will never go back.  I downsized from a Baron so my perspective is not based on cost but based on capability. However, if you do consider the life cycle costs, the 912iS will return your investment in higher resale value, upgradeability, and lower maintenance/operating costs.  

In terms of power, our 912iSc sport engined P2008 climbs out of Mammoth Lakes on a 90 degree day, with full tanks, two on board, one bag, at 1000fpm at 80KIAS.  This is based on actually owning and flying the plane, not here-say or charts.  There has been much made of “early issues” with the 912iS.  In all cases it has been the install, not the engine.  Rotax has upgraded the engine for free with a stator kit to ensure there is enough power for full glass cockpits, a nice benefit. The 912iS requires a more robust installation, as mentioned, things like metal fuel lines which require exact fits, unlike rubber hose, but it also requires the sensor tiedown kit, which is a few hundred dollar kit, with sensor specific tie downs to eliminate false alarms due to sensor vibration.  Many of the early installs didnt have this, mine didn’t so we immediately added it and this is likely why we have had zero faults.  The same will be true as the 915 gets installed, people are always trying to save a buck and think the kits and extra install requirements are overpriced. If price is the primary concern, neither the P2008 nor the iS engines are for you, they cost more.

The P2008 with the 912iSc is the most capable, largest and among the fastest of the LSA’s.  With the CS prop on it, it will likely be the fastest of all of the LSA’s and the fit, finish and refinement of this airplane is beyond compare.  It’s expensive but in this case you get what you pay for and given the comfort, performance and reliability, it’s well worth it for us.  At this stage of the LSA market, buying a carb’d Rotax is truly short sighted in my view.  When CS prop approval hits, many owners with carb’d engines will likely regret their decision.

2 cents worth from an owner, I’d say buy the 912iS or wait until the 915 is available, avoid the old tech dual carb’d engines regardless of cost.

[sandpiper]

11 minutes ago, 912iS Fanatic said:

I’ve been flying a P2008 with the 912iS  for over 3 1/2 years out of CA, in the mountains.  The engine is by far the most reliable Rotax ever made.  Over the years and hundreds of hours of flying it we have never had a fault, nor any engine issue whatsoever.  The 912iS with the sport upgrade sips fuel (<3.5 gph), and maintains at least 110 KIAS through 12,000 MSL.  In our family we have also had two 912ULS powered planes, and one 914.  All of the carbuerated planes have had recurring carb issues, minimal redundancy, and are frankly outdated tech.  

When single lever constant speed (CS) props become available, hopefully late this year, only the iS engines will be eligible since they are full fadec engines, that means only the 912iS or 915iS.  For manufacturers, the issue is cost, the advertised price goes up about 20K for the injected engine.  The injected engines have/require among other things metal fuel lines, high pressure filters, and provide substantially more electrical power along with over 27 engine sensors and dual redundant Engine Control Units (ECU).  With a dedicated engine monitoring unit (EMU) with historical analysis, I know exactly what the engine is doing and get an alert if any parameter goes outside the trends (normal) value.  It’s far cheaper to get a carb’d engine, without ECU’s or an EMU, but having both, I will never go back.  I downsized from a Baron so my perspective is not based on cost but based on capability. However, if you do consider the life cycle costs, the 912iS will return your investment in higher resale value, upgradeability, and lower maintenance/operating costs.  

In terms of power, our 912iSc sport engined P2008 climbs out of Mammoth Lakes on a 90 degree day, with full tanks, two on board, one bag, at 1000fpm at 80KIAS.  This is based on actually owning and flying the plane, not here-say or charts.  There has been much made of “early issues” with the 912iS.  In all cases it has been the install, not the engine.  Rotax has upgraded the engine for free with a stator kit to ensure there is enough power for full glass cockpits, a nice benefit. The 912iS requires a more robust installation, as mentioned, things like metal fuel lines which require exact fits, unlike rubber hose, but it also requires the sensor tiedown kit, which is a few hundred dollar kit, with sensor specific tie downs to eliminate false alarms due to sensor vibration.  Many of the early installs didnt have this, mine didn’t so we immediately added it and this is likely why we have had zero faults.  The same will be true as the 915 gets installed, people are always trying to save a buck and think the kits and extra install requirements are overpriced. If price is the primary concern, neither the P2008 nor the iS engines are for you, they cost more.

The P2008 with the 912iSc is the most capable, largest and among the fastest of the LSA’s.  With the CS prop on it, it will likely be the fastest of all of the LSA’s and the fit, finish and refinement of this airplane is beyond compare.  It’s expensive but in this case you get what you pay for and given the comfort, performance and reliability, it’s well worth it for us.  At this stage of the LSA market, buying a carb’d Rotax is truly short sighted in my view.  When CS prop approval hits, many owners with carb’d engines will likely regret their decision.

2 cents worth from an owner, I’d say buy the 912iS or wait until the 915 is available, avoid the old tech dual carb’d engines regardless of cost.

Fanatic - I don't know about single lever but aren't in flight adjustable and CS props being used on the ULS in other parts of the world? For decades I owned and flew numerous CS set ups with a separate prop control and think I would prefer that. But, then, I have never flown nor been a passenger in a single lever set up so ............

By the way, the P2008 is a beautiful plane, as you know.

[Warmi]

I kind of regret getting 912 ULS but it came with a slightly used plane and it was a reasonable deal so not much choice there ... but my next plane wil definitely have one  of the fuel injected engines.

One thing I noticed though is that about every Rotax mechanic I spoke to ( and even some plane dealers ) were advising against buying 912Is equipped planes ... I wonder if this is the same defensive mechanism among maintenance personnel that used to be common back in the 70s and 80s when fuel injected cars were becoming the norm... or do they know something about 912is we don’t..

[solarguy54]

2 hours ago, Warmi said:

I kind of regret getting 912 ULS but it came with a slightly used plane and it was a reasonable deal so not much choice there ... but my next plane wil definitely have one  of the fuel injected engines.

One thing I noticed though is that about every Rotax mechanic I spoke to ( and even some plane dealers ) were advising against buying 912Is equipped planes ... I wonder if this is the same defensive mechanism among maintenance personnel that used to be common back in the 70s and 80s when fuel injected cars were becoming the norm... or do they know something about 912is we don’t..

I'm an LSRM with a small LSA service/flight center in AZ. I've been reluctant to recommend or invest in the 912 iS due to two things. 1. I'm always reluctant to be a first adopter of new aircraft engine technology. And, there were a lot of SBs on the 912 iS early on.  2. Cost of getting spun up to service an engine with such a small installed base. The price for the diagnostic software/interface is close to $1000. That being said, my next personal aircraft WILL have a 912 iS engine and I will buy the BUDS Level 2 service kit. Why? I believe that the iS line of engines is the future of aviation and that Rotax will give Lycoming and Continental a run for their money. And I have two customers who now have the 912 iS (neither have needed work on their engine yet). I heard a rumor at OSH that Rotax has a 6 cylinder development project with 200+ hp. Looking forward to the fewer pneumatic synchronizations!

[912iS Fanatic]

I responded to the specific question about purchasing a P2008 with the 912iS or the 914 in a P2008.  For that question I’m a firm advocate of the injected engine.  Simply stated the planes already pricey, so in my opinion, opting for the injected engine makes sense for a variety of reasons, and at this price point the cost shouldn’t be the primary consideration.

In terms of the CS prop, as I understand it, there is only one solution for US-LSA’s being evaluated, and that is for a single lever control, and only the iS engines are able to interface with this system.  The single lever requirement is what caused the altitude compensated carbs to be implemented versus a mixture control so it is likely the FAA will remain steadfast on this requirement.  This is beyond my experience base so will leave that debate to the forum.  Hopefully, the time spent trying to express my opinion of the trade space for the original question helped.  

I’ll leave this forum to the CT crowd who know that very capable airframe.

[Tom Baker]

The addition of a controllable pitch propeller may require a single lever control, at present a single lever control is not required. You can have separate throttle and mixture controls.