GravityKnight Posted September 12, 2013 Report Share Posted September 12, 2013 What about high altitude power differences? I live at 6700ft elevation, I need all I can get. I did a lot of performance ecu tuning in the auto world. Good tuning makes a huge difference to efficiency and power. I know the carbs on the 912uls are altitude adjusting, but how good at this task are they? Has anyone ever ran a wideband a/f gauge in an airplace with these types of carbs I wonder? Even fuel injection requires tweaking to the tune to get it right when you make massive altitude swings. (If you are particular like me). Does anyone know if the injected 912 is speed density based? In theory, the injected engine should produce slightly more power at high altitude across a broad spectrum of outside temps and the like... but I wonder if it really does... just curious... Link to comment Share on other sites More sharing options...
Roger Lee Posted September 12, 2013 Report Share Posted September 12, 2013 To fine tune a little better you can do this, At that altitude I would set the carb needle to the #2 clip position instead of #3 clip position and make sure my prop could get at least 5600-5700 rpm WOT at your average altitude. Ed, I would do the same for your circumstances with a field elevation of 7100'. Keep in mind that if you go to sea level like that to keep an eye on temps and when the weather turns cold and dry it will lean even farther. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted September 12, 2013 Author Report Share Posted September 12, 2013 Thanks, I'll think about having Jeremy change my needle setting at my upcoming inspection. Kurt, you are liking even position #1? Roger, you are softening on moving the needles? Link to comment Share on other sites More sharing options...
Roger Lee Posted September 12, 2013 Report Share Posted September 12, 2013 Hi Paul, That isn't quite how it works and especially with CT since they wired them both to the ignition key switch instead of having two independent switches like Rotax wanted. Technically you are supposed to turn on both Lane A and Lane B switches ( Lane is just another name for computer A and . When it starts it starts just on the battery and on the one computer. It will stay on battery power until you increase the throttle past 2750 rpm then the generators come on line and the computer switches over. There are two generators. A 16 amp and a 30 amp. So once you start it you let it warm for a few moments then increase throttle above 2750 (i.e. 3000 rpm) and when the computer switches and the gens come on line you reduce back to your warm up rpm of 2100-2400 rpm. For me I would get away from the old school teachings of turn everything on before you start and just start the engine, get both gens on line then start switching lights, radios, ect.. on line. My engine with the soft start modules starts smoother than the 912is. So starts and stops are still a little rough compared to other engines because of the high compression. We had a 912is engine on a stand in Nassau and did a number of starts and stops while hooked up to a computer and we pulled lots of sensor plugs off to cause the engine to go into minor and major computer faults to see what happened. Minor faults you still fly no matter how many. Get two major faults like one on each Lane and your done. If FD had made two switches instead of one you could switch one lane off and try to reset or check one Lane over the other, but they ran them together. Link to comment Share on other sites More sharing options...
Roger Lee Posted September 12, 2013 Report Share Posted September 12, 2013 "Roger, you are softening on moving the needles?" .No just do it with good sound reasoning, like flying high all the time, like you. You and Gravity would be good candidates. It isn't for everyone, but you and gravity live and fly in circumstances that are suited for this type of change. Do it with the knowledge that things can change quickly and how it will affect your fuel burn and temps and what happens when you go from always flying at 11K' all the time to sea level on a cold day all of a sudden. Doing it at sea level isn't a good thing and can take it's toll over the life of the engine or if there is a change in something you have no buffer and cause damage before you can even act. If Rotax with more than 23+ years of experience and millions of flight hours thought #1 was better at sea level there would be some provision for this, but they are fairly adamant about not doing this. Too many figure that if it doesn't destroy my engine after 1-2 flights it must be okay and never look at the long term affects. There are pilots here that can tell us what happens when you fly too lean for too many hours in a Cont. or a Lycoming. It may be fine for a for quite a while, but longevity suffers. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted September 12, 2013 Report Share Posted September 12, 2013 Per the AOI, you start engine with GEN A, you then wait for min oil temp (122) to engage GEN B which requires you to go to 3,000 rpm for 10 seconds. It says it can take 2-5 mins to get to 122 depending on OAT. You then turn on avionics. If you turn on avionics before GEN B engaged, you are using batttery. "This can drain the battery very fast." I don't have any real world experience yet with the "i", so if anyone knows differently please correct me. That kind of sucks. How do you know if you are at minimum oil temp, or even if you have any oil pressure at all, if you can't start your fancy Skyview EMS for five minutes after you start the engine? How many 912iS engines are going to seize up due to this I wonder... Link to comment Share on other sites More sharing options...
Roger Lee Posted September 12, 2013 Report Share Posted September 12, 2013 If you don't have minimum oil pressure it will show a fault on the panel lights. You could turn on the EMS, just not everything on the panel like some do. Link to comment Share on other sites More sharing options...
Duane Jefts Posted September 12, 2013 Report Share Posted September 12, 2013 That kind of sucks. How do you know if you are at minimum oil temp, or even if you have any oil pressure at all, if you can't start your fancy Skyview EMS for five minutes after you start the engine? How many 912iS engines are going to seize up due to this I wonder... CTLSi start - aux fuel pump on, master switch on, Gen switch on, ACL on, fuel shut off open, fuel sel both, throttle idle, ecu backup switch off, clear, ignition key to start, after eng start lane A and B warn lights must illuminate and extinguish within 2-5seconds to confirm ECU self test good, oil press ck, fuel press ck, throttle 2000 rpm, warm up about 2 min - oil temp 122f or above, gen B -rpm 3000 for 10 sec, ck pos charging current, avionics switch on. Easy to do. On before t/o ck list just check lane A and B similar to mag check. Both lane lights out - good to go. Link to comment Share on other sites More sharing options...
chanik Posted September 12, 2013 Report Share Posted September 12, 2013 I have 26 months at #1 needles now. EGT stays below 1450 reliably and I'm at sea level. It can be problematic in Summer in Tuscon though, I would concur. I do a lot of very long range flying and 1/2 the time am also crossing the Sierras at 13K. The fuel burn climbs up a lot beyond 80% throttle for only 5 more kts. Like 4.6 to 5.3gph. CHT and oil hover around 190-210 in summer (which is just ~80deg ambient here). But I can see where ROTAX would still advocate #3. Presuming accidental filling of 87 octane and a hot summer day at mid throttle; you could detonate. They want all the margin for error they can get and don't rely on pilots to carefully monitor the engine. Link to comment Share on other sites More sharing options...
sandpiper Posted September 12, 2013 Report Share Posted September 12, 2013 The temp numbers are to be pretty close to ours, but because there are many LSA some of those don't have very good cooling and air flow characteristics. Pipistrel,Vans, FD, and 1-2 others (I can't remember) are using it at this time. FD is leading the way in numbers in service and on order. I'm sure others are right on there heals. I think I heard the 400 number of IS engines out there world wide and adding more every day. Roger - you state Vans is using this engine. If so, it's not being sold yet. What do you know? Is this what's gonna hang on my -12? Link to comment Share on other sites More sharing options...
Roger Lee Posted September 12, 2013 Report Share Posted September 12, 2013 Cold dry OAT's will lean even farther. CHT and Oil Temp will be the last to show any issues and aren't as affected by the EGT's as much as the cooling from the air flow through the radiators. My EGT's are down in the mid 1300's. Depending on out side conditions and air temp to the engine one needle position change is approximately 80-90F increase on the EGT's. Link to comment Share on other sites More sharing options...
paul m Posted September 12, 2013 Report Share Posted September 12, 2013 Thanks Roger. Just relaying what I've seen in the CTLSi AOI. Looking forward to being able to give you some actual user experience feedback at some point. Link to comment Share on other sites More sharing options...
Roger Lee Posted September 12, 2013 Report Share Posted September 12, 2013 I was told Vans by Eric. I was just regurgitating info. I haven't seen one. Maybe they are just starting and don't have one to market yet? Link to comment Share on other sites More sharing options...
sandpiper Posted September 12, 2013 Report Share Posted September 12, 2013 I was told Vans by Eric. I was just regurgitating info. I haven't seen one. Maybe they are just starting and don't have one to market yet? I don't have my fuel system in yet. Maybe I should slow down. The FI engine would probably increase my empty weight from 740 to 760. I could live with that. Link to comment Share on other sites More sharing options...
chanik Posted September 13, 2013 Report Share Posted September 13, 2013 Cold dry OAT's will lean even farther. CHT and Oil Temp will be the last to show any issues and aren't as affected by the EGT's as much as the cooling from the air flow through the radiators. My EGT's are down in the mid 1300's. Depending on out side conditions and air temp to the engine one needle position change is approximately 80-90F increase on the EGT's. That was true from #3 -> #2 but I only see another 40F rise going to #1 in EGT. Link to comment Share on other sites More sharing options...
Jim Meade Posted September 13, 2013 Report Share Posted September 13, 2013 There are pilots here that can tell us what happens when you fly too lean for too many hours in a Cont. or a Lycoming. It may be fine for a for quite a while, but longevity suffers.[/font][/color] Bring them forward and tell me their names. All the information I have is you are utterly and completely wrong to state that running LOP will cause long term damage to TCM and Lycoming. It is an old wives tale told by old A&P's. What will cause the damage? I'm talking about balanced injectors. The engine is running with less fuel and thus less power and the flame front burns over a longer time. What is causing damage? Link to comment Share on other sites More sharing options...
coppercity Posted September 13, 2013 Report Share Posted September 13, 2013 We run our Cirrus SR22 lean of peak 90% of the time, it has a great set of balanced Injectors and a lean assist program. The engine runs on average 60 deg cooler on CHT vs running at best power ROP. Almost 850hrs on this IO550 with no issues. Link to comment Share on other sites More sharing options...
Roger Lee Posted September 13, 2013 Report Share Posted September 13, 2013 I'm not talking about normal lean or peak, it's the ones that try to save a gallon or a buck or milk an ounce of power. That's why 2 strokes and the 912's aren't setup that way. It is setup for engine protection not an owners who want to take it past the norm. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted September 13, 2013 Author Report Share Posted September 13, 2013 Roger, High altitude calls for leaning, period. It isn't provided for, that isn't protection, it is a lacking feature, leaning at altitude would be preferable. Link to comment Share on other sites More sharing options...
Roger Lee Posted September 13, 2013 Report Share Posted September 13, 2013 I'm just a user like you and don't Mfg them and yes it would be preferable. It is a simple engine that originally was not going to be used at the higher altitudes we use today. Things have changed since 1989 for us light aircraft users so you're going to have to lodge that complaint with Rotax. When I manufactured my dive compressors I tried to make things more or less idiot proof, but they are still out there and Rotax has them too. Link to comment Share on other sites More sharing options...
Jim Meade Posted September 13, 2013 Report Share Posted September 13, 2013 I'm not talking about normal lean or peak, it's the ones that try to save a gallon or a buck or milk an ounce of power. That's why 2 strokes and the 912's aren't setup that way. It is setup for engine protection not an owners who want to take it past the norm. Lean of peak is the modern norm for engines that are sufficiently balanced. It sounds to me like you're saying the Rotax is not sufficiently calibrated to make sure that the cylinders have about the same amount of fuel. When that happens, the one that is leanest will have insufficient fuel when the one that is richest is properly lean of peak. Thus, the engine will run rough. Enriching it so the leanest cylinder has the right amount of fuel may mean the richest cylinder is in the danger zone of between peak and 50° ROP where there is too much heat and too much pressure. When one is at high altitude in a NA engine one can't get enough air in there to make more than about 65% power and it is very difficult to damage an engine at that setting or below. Having the capability to lean at that altitude would not hurt the engine. It might run rough if set too lean, but wouldn't make enough power at any setting to do any damage. Link to comment Share on other sites More sharing options...
Scrapman1959 Posted September 16, 2013 Report Share Posted September 16, 2013 I flew nonstop yesterday from 52F to KIOW (582nm) nonstop at 5500 ft. Took 5.6 hours with winds and ran about 5.3 gph most of the trip. Started out full tanks and landed with very little in site tubes. Computer said I could go another 85nm, little voice inside of my head saying, land now, land now. Just wondering if the iS would have made any difference. DA was 7500 ft for the majority of the trip. Link to comment Share on other sites More sharing options...
opticsguy Posted September 16, 2013 Report Share Posted September 16, 2013 Northwest Regional? I used to fly there to eat at the Blue Hangar. I never saw another CT there before. Link to comment Share on other sites More sharing options...
CT4ME Posted September 16, 2013 Report Share Posted September 16, 2013 Based on all specs presented so far, in a CTLSi you would have landed with 6-7 gallons more fuel. And with the collection tank, less worries about low fuel and "wing slosh" tim Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted September 16, 2013 Author Report Share Posted September 16, 2013 Based on specs, sure but the point of this thread is to look at real world results, like when flying out west where you need altitude you might be flying without being in econo-mode. The other real world report had to question the prop pitch. Link to comment Share on other sites More sharing options...
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