Any thoughts on using peak TIT as the reference point for leaning a TSIO 550-E? This is SOP in a Cirrus with a TSIO 550-K. Well, I should clarify: the actual SOP is to use the computer generated cyan target for leaning; but leaning "manually" to lean of peak TIT is an alternate procedure. Likewise, their POH lists 30.5" MP as maximum for any LOP operations; while 29.0" - 29.5" MP is max for LOP ops in a turbo-normalized Cirrus.
Generally I prefer to see my TITs no higher than 1550ish. That seems pretty easy to maintain on the lean side of peak EGT. Anything over 1600 gets my attention and the thought of *slowy* leaning to and through whatever peak TIT might be (1700+??) makes me feel queasy. So, I try to lean through peak (EGT or otherwise) "briskly", moving the mixture control back over a period of about 3 to 6 seconds --which, incidentally, is again exactly what's recommended in a turbo normalized Cirrus (TSIO 550-N with Tornado Alley TN). Because of that, I can't say for sure that I know what peak TIT on my 550-E would actually be ...guess I'm not brave enough to try to find out!!
I'm still a Lancair neophyte with a mere 70 hours or so in the plane. I have plenty of TSIO 550 time with other planes but often consider such experience a liability. What are y'all's thoughts on adapting this Cirrus procedure for a 550-K for use on a 550-E? And should we also limit the MP to 30.5 when operating LOP? Again, I realize that my Cirrus experience could be misleading me here, but it's hard to ignore the fact that their POH's are standardized, updated, and honed over many years of operational experience with a vast fleet of planes. Thoughts?
Thanks,
Ken
PS. I find the left TIT consistently runs about 20 to 50 degrees warmer than the right at just about any power setting. Is this common?
Leaning to Peak TIT -50 / -75
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George Wehrung
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I haven’t heard of that but I will let some of usual IV-P operators answer that. Bob Pastusek????
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J.C. Peterson
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Hi Ken.
There’s a lot to cover here.
A general rule of thumb is no more than 1650° in cruise, but I have always preferred under 1600° if the engine will run happily there. The one big caveat to all this is TIT indications will vary depending on the location of the TIT probe in the exhaust system and the condition of the probes themselves. The probe in the photos is the worst I’ve ever seen, and it started reading noticeably higher than the other for about 20 hours before it finally gave up. It was from a Tornado Alley Cirrus.
As an aside, using that method on some 550Es when at 31”+ MP can cause a momentary backfire. It’s loud enough to get your attention in a hurry. I’ve had a few engines do that within seconds of going LOP and others wait several minutes. One in particular would backfire about every 5 minutes. Reducing power slightly to around 28” before going LOP always resolved this. I’ve spoken with a number of people over the years and none could explain why some do it, but nothing is wrong with the engine necessarily. It’s basically a lean backfire when the engine momentarily stops running and then unburned fuel lights off in the turbos. Your engine may or may not do this, but if it does that’s the fix.
Let me know if there is anything else you’d like more information on. I’ve been flying TSIO-550s for about 15 years on Lancairs and the occasional Cirrus and worked on them as a mechanic for about 10 years as well.
J.C. Peterson
Elite Pilot Services
There’s a lot to cover here.
Limitations for one type (or subtype, if you prefer) engine, especially turbonormalized, are not going to carry over to another type of engine. Just as an example, the TN Tornado Alley kit on the Cirrus are rated at 85% power continuously. Do NOT try that on your 550E. It is limited to 75% continuous ROP, and depending on how you interpret Continental’s operations recommendations to 65% power LOP. Continental historically hasn’t exactly endorsed LOP ops, but they also haven’t put restrictions on it either for what it’s worth.Ken Hand wrote: ↑Sun Nov 26, 2023 6:07 am Any thoughts on using peak TIT as the reference point for leaning a TSIO 550-E? This is SOP in a Cirrus with a TSIO 550-K. Well, I should clarify: the actual SOP is to use the computer generated cyan target for leaning; but leaning "manually" to lean of peak TIT is an alternate procedure. Likewise, their POH lists 30.5" MP as maximum for any LOP operations; while 29.0" - 29.5" MP is max for LOP ops in a turbo-normalized Cirrus.
This technique is often referred to as “the big pull.” I wholeheartedly recommend doing just that as it puts engine in its biggest danger zone for the least amount of time possible. I can almost guarantee your TIT would be well above 1700°. Continental states the limit for max continuous TIT as 1750° and a 30 second limit of 1850°. I would not recommend operating anywhere close to those limits, however. You can find the limits linked here: https://www.easa.europa.eu/en/downloads/7639/enKen Hand wrote: ↑Sun Nov 26, 2023 6:07 am Generally I prefer to see my TITs no higher than 1550ish. That seems pretty easy to maintain on the lean side of peak EGT. Anything over 1600 gets my attention and the thought of *slowy* leaning to and through whatever peak TIT might be (1700+??) makes me feel queasy. So, I try to lean through peak (EGT or otherwise) "briskly", moving the mixture control back over a period of about 3 to 6 seconds --which, incidentally, is again exactly what's recommended in a turbo normalized Cirrus (TSIO 550-N with Tornado Alley TN). Because of that, I can't say for sure that I know what peak TIT on my 550-E would actually be ...guess I'm not brave enough to try to find out!!
A general rule of thumb is no more than 1650° in cruise, but I have always preferred under 1600° if the engine will run happily there. The one big caveat to all this is TIT indications will vary depending on the location of the TIT probe in the exhaust system and the condition of the probes themselves. The probe in the photos is the worst I’ve ever seen, and it started reading noticeably higher than the other for about 20 hours before it finally gave up. It was from a Tornado Alley Cirrus.
As an aside, using that method on some 550Es when at 31”+ MP can cause a momentary backfire. It’s loud enough to get your attention in a hurry. I’ve had a few engines do that within seconds of going LOP and others wait several minutes. One in particular would backfire about every 5 minutes. Reducing power slightly to around 28” before going LOP always resolved this. I’ve spoken with a number of people over the years and none could explain why some do it, but nothing is wrong with the engine necessarily. It’s basically a lean backfire when the engine momentarily stops running and then unburned fuel lights off in the turbos. Your engine may or may not do this, but if it does that’s the fix.
The short answer is no. 31.5” at 2500 rpm ROP equates to 75% power, the maximum recommended by Continental. My personal comfort zone operating LOP is 28.5” at 2500 rpm (or 2400 rpm since it’s quieter). That equates to 60-65% power depending on how it’s calculated and theoretical loses running LOP. That is in agreement with Continental’s recommendation.
That is absolutely normal. The differences in probes alone could cause that much delta. Engines will almost never have equal airflow, fuel flow, compression, spark plug condition, exhaust restriction, etc. from one cylinder to the next. Multiply that times three cylinders per turbo and it’s pretty amazing they are within 20-50°.
Let me know if there is anything else you’d like more information on. I’ve been flying TSIO-550s for about 15 years on Lancairs and the occasional Cirrus and worked on them as a mechanic for about 10 years as well.
J.C. Peterson
Elite Pilot Services
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Ken, this is a great question. Also, welcome to Lancair ownership!
LOP is doable on most engines with tuned injectors and a decent induction system. I'm sure there will be IV owners that have specific LOP experience with your engine. I fly 90% of my IO-550 LOP and it is awesome. 20% reduction in fuel consumption for 5% loss in airspeed. I think that is a fair trade. Please do some Mike Busch reading as he breaks it down well and discusses the Red Box and how to stay out of it. My recommendation is to use the TCM engine data for your specific engine vs using Cirrus POH info. I found that aircraft manufacturers sometimes have power combos that make their planes hit claimed speeds, but are bad for engine longevity.
Figure out what your power combo is for 65% and you'll be pretty safe on working out the LOP technique. My recommendation is to do the Big Power Pull and establish well LOP. Pull until you feel a slight loss of power. Typically, you will both hear and feel the slight loss in power. Let the gauges stabilize and then enrichen to peak. Note FF, TIT, CHT, etc. You can explore how well your engine runs at 50 and 25 LOP, and at Peak.
I previously owned a turbo Mooney Bravo and I also used 1550 TIT for engine longevity. Turbo engines have the potential to boost past 65% at cruise altitude, so you may not like the speed penalty if you routinely fly at 75% during cruise. Also, you may find that you can fly peak at lower altitudes, but not at the mid FLs.
Here is some good Busch reading. https://resources.savvyaviation.com/wp- ... ed-fin.pdf
LOP is doable on most engines with tuned injectors and a decent induction system. I'm sure there will be IV owners that have specific LOP experience with your engine. I fly 90% of my IO-550 LOP and it is awesome. 20% reduction in fuel consumption for 5% loss in airspeed. I think that is a fair trade. Please do some Mike Busch reading as he breaks it down well and discusses the Red Box and how to stay out of it. My recommendation is to use the TCM engine data for your specific engine vs using Cirrus POH info. I found that aircraft manufacturers sometimes have power combos that make their planes hit claimed speeds, but are bad for engine longevity.
Figure out what your power combo is for 65% and you'll be pretty safe on working out the LOP technique. My recommendation is to do the Big Power Pull and establish well LOP. Pull until you feel a slight loss of power. Typically, you will both hear and feel the slight loss in power. Let the gauges stabilize and then enrichen to peak. Note FF, TIT, CHT, etc. You can explore how well your engine runs at 50 and 25 LOP, and at Peak.
I previously owned a turbo Mooney Bravo and I also used 1550 TIT for engine longevity. Turbo engines have the potential to boost past 65% at cruise altitude, so you may not like the speed penalty if you routinely fly at 75% during cruise. Also, you may find that you can fly peak at lower altitudes, but not at the mid FLs.
Here is some good Busch reading. https://resources.savvyaviation.com/wp- ... ed-fin.pdf
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Robert Pastusek
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I agree with what JC and Ryan posted. Two additional points.
The Continental engine Mx training folks recommend using EGTs rather than TITs. The concern is that you don’t want to operate any cylinder continuously at or near peak EGT (specifically exhaust valve temperature). TIT is an average of the three cylinders on each side; EGT is a better measurement of the individual cylinders. And BTW, a cylinder EGT that peaks early is a good indication of a partially clogged injector.
The occasional loud “pop” when operating well lean of peak is technically called an “after fire”. Basically the fuel/air charge is too lean to be ignited by the sparkplugs. The charge passes unburned into the exhaust system until it gets near the face of the turbo, where the combined flow of three cylinders is hot enough light off the charge—basically an explosion inside the exhaust system. The Continental gurus say this won’t hurt the engine, but my principal passenger finds it totally unacceptable—right up there with engine “roll-backs” when switching fuel tanks w/o turning on the electric boost pump… In any case, enriching the mixture a bit solves the problem.
Bob
The Continental engine Mx training folks recommend using EGTs rather than TITs. The concern is that you don’t want to operate any cylinder continuously at or near peak EGT (specifically exhaust valve temperature). TIT is an average of the three cylinders on each side; EGT is a better measurement of the individual cylinders. And BTW, a cylinder EGT that peaks early is a good indication of a partially clogged injector.
The occasional loud “pop” when operating well lean of peak is technically called an “after fire”. Basically the fuel/air charge is too lean to be ignited by the sparkplugs. The charge passes unburned into the exhaust system until it gets near the face of the turbo, where the combined flow of three cylinders is hot enough light off the charge—basically an explosion inside the exhaust system. The Continental gurus say this won’t hurt the engine, but my principal passenger finds it totally unacceptable—right up there with engine “roll-backs” when switching fuel tanks w/o turning on the electric boost pump… In any case, enriching the mixture a bit solves the problem.
Bob