Turbo leaning via EGT

[Schllc]

16 hours ago, Danb said:

I’m in the same camp as Lance although my Bravo ran LOP find it wasn’t worth the loss of speed nor  run with the tit above 1600, I couldn’t keep the temp under 1600 so that limited the LOP on the Bravo. I do run LOP on the Acclaim since apparently the continental runs better and supposedly lasts longer running LOP. I still have difficulty getting the settings set up properly while staying under 1600 in th Acclaim. I’m obviously not setting it up fast enough to stay out of harm’s way. Not sure of the best way to get to my cruise settings either using lean find or the big pull to the fuel flow or just guessing. 

I used the lean page on each new plane just to see where my fuel flow would fall on all of my typical power settings settings. 
Once I knew this, after I finished the climb and stabilized at full rich, I set my prop, and MP, then I will just pull the red knob all the way back to my power setting, predicated on my known fuel flow. I don’t stay in the red box at all.

I prefer 29”MP, 2400rpm, and LOP this puts me at approximately 15.0-15.6 depending on load and conditions, using TIT. 
ROP at same settings should be between 18.5-20gph, depending on your particular engine.

all of the ones I have flown have been different, until either a good fuel setup, and/or gami’s are done, it’s not likely to perform in these ranges. 
My first acclaim took north of 23gph ROP, and didn’t tolerate LOP well.  After four rounds of gami’s, it ran buttery smooth LOP, and 18.5gph ROP, with the exact same speeds. 
after a few hundred hours you can really hear your engine talking to you. 
if you put the cost of these procedures is of putting look at how quickly 5gph will take to pay for it, not to mention the other effects of running all the additional fuel through 5e system. 

[jlunseth]

Some thoughts. First a caveat, I don’t fly a Bravo, I fly a 231 which has a different engine, albeit a turbo. The power settings I may refer to in this post are not Bravo power settings.

There seems to be some misunderstanding about leaning to peak EGT and leaning to peak TIT. The GAMI people teach - and it is true - that one should always lean to peak EGT. The reason is that in a multi-cylinder engine it is entirely possible that the fuel flows can be imbalanced between the cylinders, so one cylinder can be operating happily out of the red box while another is running in the box. That is why, in order to run LOP, it is always recommended to run lean tests on the engine first, to determine how balanced the fuel flows are, and if out of balance, to install GAMI’s to bring them within .5 GPH of each other.

Once you have done that, and experimented with your power settings until you know what settings work and will give you balanced fuel flows, it does not matter any longer how you get there. I have not run a leaning operation on my engine in years, to determine which cylinder peaks first or last, but I almost always run LOP at cruise. To make my favorite LOP power setting, which is 34”/2450/11.1-.3 in my engine, I just put in the power setting and then I monitor TIT to keep it at or under 1600, with a slight allowance to rise up to 1610 so long as the rise is stable and the temp does not just keep rising on its own. But I am able to do that because I did the experiments, years ago, so I know with confidence what is going on with the individual cylinders. I can’t speak for Mike Busch, but when people with substantial experience with their engine talk about using TIT or doing the “big pull” (which I do to get to the lean side), they know what their engine is doing internally, and whatever indicator is easiest to use in the cockpit is the one they will use to manage the engine, whether that is TIT, or EGT, or something else (i.e. MP + FF).

One recommendation I would make to the OP is that, unless you have an engine monitor that reads on each separate cylinder (sounds like you do not) you just should not experiment with LOP in that Bravo engine until you do (sounds like that is on the drawing boards). ROP will be as safer place to run the engine.

There is some misunderstanding about the 1750 number. That is the redline limit, not a peak TIT. Actual peak TIT will vary depending on the power setting at which you do your leaning to find peak. In my engine, if I find peak at 28”/2450, that peak is going to be completely different than if I find peak at 32”/2450. The TIT limits in the POH are not there for the sake of the cylinders. They are there because of the metallurgy of the turbine. If the temp exceeds redline, the turbine blades become slightly malleable and can stretch because of the centrifugal force of the turbine. If they do that, they wear against the side walls and you will be needing a new turbine. There will always be some difference between the TIT, and the average temp of the EGTs. TIT will generally be hotter because there are secondary combustion events going on after the exhaust gas leaves the exhaust port (where EGT is measured) and before it gets to the turbo (where TIT is measured). So to summarize, TIT protects the turbine, not the cylinders, and actual temp of the gas at the turbine (which is different from temp at or in the cylinders) is used for that purpose.

[Jetpilot86]

12 hours ago, Shadrach said:

That is a big CHT spread. Was it running smoothly? I have a hard time believing that an 85° delta is accounted for by cooling  airflow variance alone. Seems to me those cylinders were at significantly different power settings (FF). 

I had to haul goodies back and forth to MIA last night so no flight tests today to figure that out. Hopefully, I’ll catch some decent weather when I can try again in 10 days. 

[Jetpilot86]

6 hours ago, jlunseth said:

One recommendation I would make to the OP is that, unless you have an engine monitor that reads on each separate cylinder (sounds like you do not) you just should not experiment with LOP in that Bravo engine until you do (sounds like that is on the drawing boards). ROP will be as safer place to run the engine.

I’ve got one that does capture each CHT/EGT, an Insight G2. It will capture more Types of data, but I need to hook up the other wire bundle (more AMU’s) to get at least TIT & FF for better analysis per Savvy. 

[Shadrach]

On 12/7/2023 at 7:36 PM, Rick Junkin said:

The words I used were a paraphrased quote of Mike Busch in a webinar saying he never looks at EGT and knows he’s LOP when he feels the slight decrease in power as he pulls the mixture, and then leans more as needed to get to the CHT and fuel remaining at destination numbers he wants to see.

Indeed that’s true. But it’s because he knows his airplane. I think it unlikely that he would get in another plane (even one of the same make and model) and set power that way without verifying that the engines were conforming to expectations. The truth is once you get really comfortable with a particular power plant and application you recognize other cues outside raw numbers. If my engine monitor failed a thousand nautical miles from home, I would be perfectly comfortable flying home. My power settings would likely be very close to what they would if I were using engine data. I know my plane. I know what to expect in terms of indicated airspeed. I know where the mixture is when speed seriously starts to drop off.
However, if I were ferrying someone else’s 67 M20F sans engine monitor, you better believe I would be more thorough and conservative.

[Schllc]

1 hour ago, Jetpilot86 said:

I’ve got one that does capture each CHT/EGT, an Insight G2. It will capture more Types of data, but I need to hook up the other wire bundle (more AMU’s) to get at least TIT & FF for better analysis per Savvy. 

I thought a TIT gauge was min equip for a turbo?

[Schllc]

1 hour ago, Shadrach said:

The truth is once you get really comfortable with a particular power plant and application you recognize other cues outside raw numbers.

Can agree with this enough!

My EIS lru failed recently and I lost most of my instruments but what was left was easy for me to dial in because my bird talks to me. 
If you pay attention to your plane she will always talk to you…

[LANCECASPER]

3 hours ago, Schllc said:

I thought a TIT gauge was min equip for a turbo?

He still has the factory TIT gauge installed.

[Schllc]

5 hours ago, Jetpilot86 said:

I’ve got one that does capture each CHT/EGT, an Insight G2. It will capture more Types of data, but I need to hook up the other wire bundle (more AMU’s) to get at least TIT & FF for better analysis per Savvy. 

This reads like he does not have TIT, but perhaps he meant he can’t collect the data on TIT from the G2?

[Shadrach]

32 minutes ago, Schllc said:

This reads like he does not have TIT, but perhaps he meant he can’t collect the data on TIT from the G2?

He has the factory TIT

edit- Lance beat me to it.

[Jetpilot86]

47 minutes ago, Schllc said:

This reads like he does not have TIT, but perhaps he meant he can’t collect the data on TIT from the G2?

Correct. Posting tired. 

[jlunseth]

On 12/7/2023 at 8:54 PM, Shadrach said:

That is a big CHT spread. Was it running smoothly? I have a hard time believing that an 85° delta is accounted for by cooling  airflow variance alone. Seems to me those cylinders were at significantly different power settings (FF). 

You would be surprised. As I mentioned before, I have a new engine that I am just breaking in, so no LOP experiments for awhile. The old engine had a Delta of 85 degrees from hottest (#2) to coldest (#6) at cruise. I experimented quite a bit to find out if I had a fuel flow difference that could be causing that and could not see one. The real suspect was a wrinkle in the baffle above the #2 cylinder. Knowing the engine was going to be replaced I just put up with the Delta, as it turned out for more than 500 hours. The engine was retired at 2300 which is 500 over TBO for the old 231 engines. Guess which cylinder, predictably, was showing low compressions (the hot #2 of course). The Delta in the new engine is about 35 degrees. We replaced the baffling. One contributor to the large Delta was that #6 sits dead center in the “big hole” in front of the cowling in my 231. There are two holes of the same size of course, but the starboard hole is about 50% blocked by the induction air structure while the #6 is unblocked. Also, the new engine of course has a new fuel system (same old GAMIs) so there is no real way to know what caused the difference. But based on what I saw over the years, it appeared to be cooling and not fuel flow. Not suggesting your surmise is wrong, a fuel flow difference is where I would start looking also ( and did in my old engine) but a Delta that large due to cooling is possible I think.

[T. Peterson]

On 12/6/2023 at 1:46 AM, Jetpilot86 said:

Just installed an Insight G2 today, in my new to me Bravo, replacing my Insight 602, as a cheap, and quick to install bridge to feed some engine data on my new FOH TIO-540 to @kortopates for analysis.  Here’s an old thread on engine monitors

Since I used the old 602 harness to save install AMU’s for the JPI-930 upgrade next winter,I won’t have TIT, Fuel Flow, or OAT functions via the unit for now.  After frying my brain in the TLS Bravo Power Setting Blog, I’m curious about how the G2 can be integrated into the power management of my Bravo as she seems so tied to TIT for leaning in conjunction with the Analog TIT still remaining in the panel for the time being. For instance, any value added leaning with EGT on the Turbo?

Not looking to get into any LOP areas now as I lack the engine tweaks @DVA has done to even make it possible to run LOP, but use what I have now to run the engine as precisely and efficiently as I can while waiting for next upgrade season.  I just got my beauty and want to fly her instead of just admire her in pieces in the hangar. 
 

Cheers,

just got my beauty and want to fly her instead of just admire her in pieces in the hangar. 
 

Absolutely!!! Have a wonderful time!

[Jetpilot86]

47 minutes ago, jlunseth said:

You would be surprised. As I mentioned before, I have a new engine that I am just breaking in, so no LOP experiments for awhile. The old engine had a Delta of 85 degrees from hottest (#2) to coldest (#6) at cruise. I experimented quite a bit to find out if I had a fuel flow difference that could be causing that and could not see one. The real suspect was a wrinkle in the baffle above the #2 cylinder. Knowing the engine was going to be replaced I just put up with the Delta, as it turned out for more than 500 hours. The engine was retired at 2300 which is 500 over TBO for the old 231 engines. Guess which cylinder, predictably, was showing low compressions (the hot #2 of course). The Delta in the new engine is about 35 degrees. We replaced the baffling. One contributor to the large Delta was that #6 sits dead center in the “big hole” in front of the cowling in my 231. There are two holes of the same size of course, but the starboard hole is about 50% blocked by the induction air structure while the #6 is unblocked. Also, the new engine of course has a new fuel system (same old GAMIs) so there is no real way to know what caused the difference. But based on what I saw over the years, it appeared to be cooling and not fuel flow. Not suggesting your surmise is wrong, a fuel flow difference is where I would start looking also ( and did in my old engine) but a Delta that large due to cooling is possible I think.

Savvy is saying do the baffles first. I’m guessing the middle top is the main culprit. I’ve also got a new TIT on order as the old logs went with the old engine, I have no idea how old the current TIT is. 
 

Injectors (non GAMI), and Champion plugs are new with the engine, but as soon as I have the data recording dialed in, let the injector & plug debate begin!

[Shadrach]

1 hour ago, jlunseth said:

You would be surprised. As I mentioned before, I have a new engine that I am just breaking in, so no LOP experiments for awhile. The old engine had a Delta of 85 degrees from hottest (#2) to coldest (#6) at cruise. I experimented quite a bit to find out if I had a fuel flow difference that could be causing that and could not see one. The real suspect was a wrinkle in the baffle above the #2 cylinder. Knowing the engine was going to be replaced I just put up with the Delta, as it turned out for more than 500 hours. The engine was retired at 2300 which is 500 over TBO for the old 231 engines. Guess which cylinder, predictably, was showing low compressions (the hot #2 of course). The Delta in the new engine is about 35 degrees. We replaced the baffling. One contributor to the large Delta was that #6 sits dead center in the “big hole” in front of the cowling in my 231. There are two holes of the same size of course, but the starboard hole is about 50% blocked by the induction air structure while the #6 is unblocked. Also, the new engine of course has a new fuel system (same old GAMIs) so there is no real way to know what caused the difference. But based on what I saw over the years, it appeared to be cooling and not fuel flow. Not suggesting your surmise is wrong, a fuel flow difference is where I would start looking also ( and did in my old engine) but a Delta that large due to cooling is possible I think.

I agree totally that a baffle seal issue could create such an issue. However, context is important here. I would expect such an issue to manifest in climb. I got the impression (perhaps incorrectly) that this was only happening in cruise with the engine leaned.  I am also taking for granted that this ~50hrs SFOH engine has new baffles and seals. 

[Jetpilot86]

2 hours ago, Shadrach said:

I agree totally that a baffle seal issue could create such an issue. However, context is important here. I would expect such an issue to manifest in climb. I got the impression (perhaps incorrectly) that this was only happening in cruise with the engine leaned.  I am also taking for granted that this ~50hrs SFOH engine has new baffles and seals. 

Those were cruise numbers, attached are closeups from takeoff/climb/cruise. 

I would have assumed it might have new baffles as well, and perhaps even a new TIT probe, now I’m assuming not as likely. I’ll find out how the TIT looks next week. 
 

At the rate I’m going, I’ll be ready for my A&P practical next week. 

[Fly Boomer]

3 hours ago, Jetpilot86 said:

Injectors (non GAMI), and Champion plugs are new with the engine, but as soon as I have the data recording dialed in, let the injector & plug debate begin!

Not every engine needs GAMIs, but if your GAMI spread is too big, they are usually a semi-quick fix.

[Shadrach]

16 minutes ago, Jetpilot86 said:

Those were cruise numbers, attached are closeups from takeoff/climb/cruise. 

I would have assumed it might have new baffles as well, and perhaps even a new TIT probe, now I’m assuming not as likely. I’ll find out how the TIT looks next week. 
 

At the rate I’m going, I’ll be ready for my A&P practical next week. 

On the warm side. What is take off FF?

[Jetpilot86]

41 minutes ago, Shadrach said:

On the warm side. What is take off FF?

Off hand at least 27gph, probably higher. 

[Shadrach]

16 hours ago, Jetpilot86 said:

Off hand at least 27gph, probably higher. 

You want 29.5

[Jetpilot86]

7 hours ago, Shadrach said:

You want 29.5

I’ll keep a closer eye out next takeoff. 

[Jetpilot86]

Reading through the OEM Lycoming Engine manual that was in the plane when I bought it and found an interesting note or two:

Max TIT: 1650°F, AFM lists 1750°F in a couple of places.

Max High Power Cruise CHT:  435°F, Econ Cruise:  400°F

Setting Best Econ cruise(looks like for any power setting):  Lean to 1650°F, observe CHT limits. 
Max Power Cruise:  Set the power, lean to the lower of 1650°F or peak TIT & then subtract 125°F. This becomes the new target TIT instead of 1650°

Next, Full rich Mixture, set power as desired, lean to the lower of 1525°F or 125°RO TIT peak. This will be a Best Power mixture. And different from anything I’ve seen posted here, but not far off of what @donkaye is using now. 
It fits in with some of the direct lean techniques here like @donkaye’s and others who have a lot of time with their engines. 
I’m curious how it fits in with the Red Box model. The pages from the Engine Manual are attached. 
 

I’ll be interested to see how this compares to my last power test in a week or so since the 125° offset would have had me in the 1450 range, assuming the TIT is not in bad shape.  Even so, the method would seem to apply for a deteriorating TIT. 

[LANCECASPER]

12 hours ago, Jetpilot86 said:

Reading through the OEM Lycoming Engine manual that was in the plane when I bought it and found an interesting note or two:

Max TIT: 1650°F, AFM lists 1750°F in a couple of places.

Max High Power Cruise CHT:  435°F, Econ Cruise:  400°F

Setting Best Econ cruise(looks like for any power setting):  Lean to 1650°F, observe CHT limits. 
Max Power Cruise:  Set the power, lean to the lower of 1650°F or peak TIT & then subtract 125°F. This becomes the new target TIT instead of 1650°

Next, Full rich Mixture, set power as desired, lean to the lower of 1525°F or 125°RO TIT peak. This will be a Best Power mixture. And different from anything I’ve seen posted here, but not far off of what @donkaye is using now. 
It fits in with some of the direct lean techniques here like @donkaye’s and others who have a lot of time with their engines. 
I’m curious how it fits in with the Red Box model. The pages from the Engine Manual are attached. 
 

I’ll be interested to see how this compares to my last power test in a week or so since the 125° offset would have had me in the 1450 range, assuming the TIT is not in bad shape.  Even so, the method would seem to apply for a deteriorating TIT. 

That is an ancient 1979 Lycoming manual that was written 17 years before the TIO-540-AF1B engine (Bravo) ever existed and 10 years before the TIO-540-AF1A engine existed (TLS). That booklet was made for the much heavier duty 350hp TIO-540 engines years before this that were put into Piper Navajos, as an example, that share no parts with your engine.

The lighter weight engine used in the Bravo is pushed to the max at 270hp and is used in no other airframe. The closest engine related to it is rated at only 250hp and was used in the Socata TB21.

Lycoming came up with a booklet toward the late 90's that is a little closer to reality, where they used more conservative numbers, but just keep in mind that the people who wrote this and other "official" material are not owners who have the "privilege" of buying cylinders ($3000 each for the Bravo) and overhauling engines ($100,000). I would dispose of that version properly, along with the charts on the visors that came with early M20Ms. 

In GA, long term owners and owners groups cut through all the marketing nonsense that promoted unrealistic and unattainable numbers and come up with the way that it makes the most long term economic sense to fly the airplane in real world operations. 

One other thing: you keep quoting what the MAX numbers are in this and the POH. Hopefully you would never operate a $40,000 car pegged to the redline on the numbers, with the tach, the temperatures, etc, for good reason. Your Bravo engine is worth twice what the average car is today.

[Pinecone]

11 hours ago, Jetpilot86 said:

Reading through the OEM Lycoming Engine manual that was in the plane when I bought it and found an interesting note or two:

Max TIT: 1650°F, AFM lists 1750°F in a couple of places.

Max High Power Cruise CHT:  435°F, Econ Cruise:  400°F

Setting Best Econ cruise(looks like for any power setting):  Lean to 1650°F, observe CHT limits. 
Max Power Cruise:  Set the power, lean to the lower of 1650°F or peak TIT & then subtract 125°F. This becomes the new target TIT instead of 1650°

Next, Full rich Mixture, set power as desired, lean to the lower of 1525°F or 125°RO TIT peak. This will be a Best Power mixture. And different from anything I’ve seen posted here, but not far off of what @donkaye is using now. 
It fits in with some of the direct lean techniques here like @donkaye’s and others who have a lot of time with their engines. 
I’m curious how it fits in with the Red Box model. The pages from the Engine Manual are attached. 
 

I’ll be interested to see how this compares to my last power test in a week or so since the 125° offset would have had me in the 1450 range, assuming the TIT is not in bad shape.  Even so, the method would seem to apply for a deteriorating TIT. 

Interesting that the last page shows Best Economy as Lean of Peak EGT.

 

[Shadrach]

50 minutes ago, Pinecone said:

Interesting that the last page shows Best Economy as Lean of Peak EGT.

 

That’s the same conceptual graph that Lycoming uses for all of its engines. Likely because it’s “close enough” for any fixed timing Lycoming flat engine.

It also appears in the O360 manual as well as Service Instruction 1094D, which is an interesting read. Their best power leaning procedure sounds like a lot of fun for someone flying a turbocharged twin, single pilot, hard IFR, in busy airspace.