Pre Lean with a JPI in a Bravo

[DaveMC]

Question for the group.  I am trying to refine my leaning process because I feel like I don't have it quite right yet

 

When Leaning ROP using a JPI 900 they tell you to Pre- lean.  I am curious about other Bravo owners..... What TIT do you pre lean to?  before starting your ROP leaning process?

[alextstone]

Upon reaching cruise altitude, I set my MP/RPM to 29/2400, cowl flaps either closed or half open (usually about 16k or above) and my FF to about 20 GPH.  I then wait a couple of minutes for the engine temps to stabilize.  Then, I go through the ROP or LOP leaning procedure.  

[gsxrpilot]

According to JPI, "pre-lean" is to basically move from full rich to a normal ROP mixture setting. In other words, don't start you Lean Find procedure from full rich, rather start from an acceptable ROP cruise, mixture setting.

[DaveMC]

Thank you.  Flying today and gonna really try and figure this out.  Will report back on my adventure.

[carusoam]

If you don’t pre-lean to get into the window...

You will be dialing the mixture slowly for a really long time...

Once you get a feel for where the window actually is... like Alex described above... the learning process is quite easy after that...

With a turbo, sensitivity to leaning increases... to protect the hot side’s vanes...

There is a technique used called the big pull...

to go LOP into the window without spending a lot of time in the hot peak zone...

 

Know where the peak occurs... get there, but don’t hang out...

PP thoughts only, not a mechanic or TC pilot...

Best regards,

-a-

[DaveMC]

12 hours ago, carusoam said:

If you don’t pre-lean to get into the window...

You will be dialing the mixture slowly for a really long time...

Once you get a feel for where the window actually is... like Alex described above... the learning process is quite easy after that...

With a turbo, sensitivity to leaning increases... to protect the hot side’s vanes...

There is a technique used called the big pull...

to go LOP into the window without spending a lot of time in the hot peak zone...

 

Know where the peak occurs... get there, but don’t hang out...

PP thoughts only, not a mechanic or TC pilot...

Best regards,

-a-

Thi

 

 

 

 

This is where I ended up. 

 

[kortopates]

Dan

Strongly suggest you learn all about leaning at greatly reduced power settings where there is no red box to stay out. You're using ~80% power with 29" 2400 rpm. That TIT of over 1617F is way too high if you want your exhaust components to last. You should be about 100F lower for a ROP power and under 1600F for a LOP power setting. But you want to start at less than 65% power so that you can't hurt the engine no matter where you leave the mixture and allow you to get to know how to use your EDM 900 to lean slowly as you go through peak. You still have a lot to learn and want to do it in safe sandbox without concern for damaging your engine as you do so. That means a lower power setting.  AT least use one of the lower 2 power settings out of your POH, but I'd recommend starting with the lowest of 24" 2200 rpm which 57% power. When you have the basic dialed in, then go up to 27" 2200 rpm which is 67% and learn how to set mixture relatively quickly without spending much time at peak. Power is still relatively low enough that the red box is very small. But wouldn't recommend going any higher till you fully understand the process and feel real comfortable. See Gami's AFMS for great recommendations on how far LOP and ROP you need to be based on % Power - its good safe conservative advice and FAA approved as well.

After you learn the basic at lower power settings, then you'll know enough to graduate to doing the big pull and using TIT as a proxy for leaning. But frankly you'll find the big pull doesn't work out so well in the Bravo and most Bravo's will do at most about 65-70% power LOP smoothly (if LOP is even of interest to you). 

Take your time and really learning with baby steps and you'll do great!

Edited March 7, 2020 by kortopates

[DaveMC]

2 hours ago, kortopates said:

Dan

Strongly suggest you learn all about leaning at greatly reduced power settings where there is no red box to stay out. You're using ~80% power with 29" 2400 rpm. That TIT of over 1617F is way too high if you want your exhaust components to last. You should be about 100F lower for a ROP power and under 1600F for a LOP power setting. But you want to start at less than 65% power so that you can't hurt the engine no matter where you leave the mixture and allow you to get to know how to use your EDM 900 to lean slowly as you go through peak. You still have a lot to learn and want to do it in safe sandbox without concern for damaging your engine as you do so. That means a lower power setting.  AT least use one of the lower 2 power settings out of your POH, but I'd recommend starting with the lowest of 24" 2200 rpm which 57% power. When you have the basic dialed in, then go up to 27" 2200 rpm which is 67% and learn how to set mixture relatively quickly without spending much time at peak. Power is still relatively low enough that the red box is very small. But wouldn't recommend going any higher till you fully understand the process and feel real comfortable. See Gami's AFMS for great recommendations on how far LOP and ROP you need to be based on % Power - its good safe conservative advice and FAA approved as well.

After you learn the basic at lower power settings, then you'll know enough to graduate to doing the big pull and using TIT as a proxy for leaning. But frankly you'll find the big pull doesn't work out so well in the Bravo and most Bravo's will do at most about 65-70% power LOP smoothly (if LOP is even of interest to you). 

Take your time and really learning with baby steps and you'll do great!

Hummmm,  I am following the JPI instructions to the letter....   so I will video it tomorrow.  I was reading some where in one of these blogs that the TIT should be 1600-1625 Max....  I must have misread.  

[carusoam]

Dave use an extra bit of caution with generic instructions... and advice by normally aspirated pilots (like me)...

If learning the ropes of leaning and going LOP... a TC’d bird can do things that NA’d birds can’t...

Non-turbo’d engines run out of power above 8k’ and are self limiting to things that can cause pre-ignition...

Turbo’d engines can easily stay above 65%hp so... active knowledge of what and where the red box is and knowing how to avoid it are key.  Proper control of the TIT is important to turbo health...

Fortunately we have Mr. @kortopates with us on MS... He is an experienced M20K pilot and engine monitor expert, all in one person... among other skills!

If not familiar with the red box and what it is all about... just say so... we can probably reference some good reading such as Savvy.com...

NA PP thoughts only, not a mechanic or CFI...

Best regards,

-a-

 

[gsxrpilot]

I can concur with everything @kortopates is suggesting here. I was very careful to do all my learning about LOP/ROP/Mixture settings, etc. all at 65% or below. Most of my initial LOP flights were done at 62%. This keeps me out of the red box all together and let me learn how to run the engine without being able to hurt it. 

My TIT is never above 1550 and CHT's are typically below 350.

1600 hours later and I'm still on the original cylinders and original turbo. 

[kortopates]

4 hours ago, DaveMC said:

Hummmm,  I am following the JPI instructions to the letter....   so I will video it tomorrow.  I was reading some where in one of these blogs that the TIT should be 1600-1625 Max....  I must have misread.  

Dave (sorry I used Dan earlier) the max TIT you read and am using was in the context of LOP ops not ROP as you are operating above. The discussion wasn't meant to be focused on a max  TIT, but on needing to stay out of the Red Box; especially as you are learning to lean and experimenting. The size of the red box grows with the % power and is much larger on the ROP side than the LOP. On the ROP side where you are  above, we need to be much richer to be out of it. Using Gami's recommended mixture settings for power settings above 65% to 75% we want to be 100 to 150F ROP from your leanest cylinder and on the LOP side we need only be 15 to 50F LOP on the richest cylinder.  Operating at 29" 2400 rpm, which equates to 81% power per Lycoming Operators Guide, you want to be even a bit more richer and you'd find your TIT will be about 100F lower to be as rich as suggested to do so. Its only on the LOP side, where we are much closer to peak, that we get anywhere near the limits of TIT. At Savvy we recommend a max of 1600F, I personally use 1580F knowing my TIT will creep up periodically closer to 1600F, so 1580 gives me buffer. Whom ever suggested 1600 to a max of 1625F is just operating more aggressively than I do and what we recommend at Savvy but of course your engine won't self destruct at 1601F TIT any more than it will at 1626F - its all about how conservatively or aggressive you want to run it.    

For a more thorough explanation on the Red Box there is a ton of literature by Mike Busch and Deakin on Avweb including a great series. But this article by Mike B https://www.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2012-12_red-box-red-fin.pdf explains the concept really well and really makes the point that using your lean Find mode is not the right way to lean your engine at high power settings like that because you need to go through peak slowly to find it. But you definitely want to learn all about peak and using your engine monitor is very instructive - just don't do it above 65% power since its not good for the engine.  Keep in mind when Mike B says he doesn't necessarily keep track of always care how LOP or ROP his EGTs are its because his cruise is typically no higher than 65% power. He really babies his engines to go 2-3x past TBO. But again his point there is not to rely on using your monitor to slowly find peak and set mixture. 

Additionally, you'll want to learn the specifics of your engine with respect to mixture distribution and probably the health of your ignition system. To do this, I recommend our Savvy Test profile, at http://content.savvyanalysis.com/static/pdf/SavvyAnalysisFlightTestProfiles.pdf  By going through that, you'll not only learn you gami spread but also your leanest and richest cylinders and ranking in between. You want to know your leanest for setting up or verifying ROP mixtures and your richest for LOP ops since you really don't want to have to always use your engine monitor Lean find and go through peak slowly.  

There is a great red box simulator app on the APS site that shows how it size grows with power here https://www.advancedpilot.com/redbox.html

Lastly here is the mixture guidance from GAMI/APS on where to place your mixture for both LOP and ROP that was referenced before: https://gami.com/gamijectors/AFMS - GAMIjectors Rev IR.pdf It doesn't matter whether you have gami's installed or not, its great conservative guidance. 

BTW, hope you're not relying on the % power displayed on your EDM since its indicating 77% power with a power setting rated at ~81% per Lycoming. If that's of value to you, see the calibration procedure in the EDM Pilot Guide. 

Again, since my first post wasn't understood, let me summarize: 

None of this discussion is about how to set mixture or how EDM LF works etc. Its to say that i) using your EDM to set mixture at high power settings is not good for your engine and that ii)at 80% power ROP you want to be much richer because of the red box. But to learn all about these concepts dealing with the Red box, LOP & ROP, using your Engine monitor is excellent way to do it! Just do it at lower safer power settings as you learn - such as the 65% max recommended in our Savvy Test profile. Move up to higher power settings after you learn more about your engine specifics and advanced leaning techniques which get you there faster. Going slowly through peak at what most of us consider the max recommended cruise power setting is not good for the long term health of your engine.

Rather than shoot video's, open a free account on SavvyAnalysis.com, upload your data there and you can share with us on MS by clicking on the share options bottom right (one flight at a time or even all flights). 

[gsxrpilot]

That post needs to be pinned... or in the mythical FAQ section. Great info.

[tmo]

I am so looking forward to @kortopates's presentation at the Summit...

[NicoN]

@kortopates: Thank you for your information. Extremely interesting.

We have a M20K-231 equipped with an EDM830.

The recommended procedure for lean finding needs to pre-lean the engine to a certain ROP position, then wait and after minutes do the lean-finding.

I tried this procedure pretty often. but always start the leaning pretty soon. as the temperatures are quickly rising! So, now I lean more or less down to 11.5gph, wait only few seconds and then to the lean find procedure. The EDM830 never failed to detect the LOP point. I always further lean to stay between 30 to 70° LOP and end up at 8,2 to 9.5 gph and temperatures max of 365 CHT for #2 and TIT ~1520 (TSIO-360GB).

But, during the Lean-find, the Power decreases from 67% down to ~58%. Is it legal to advance the throttle then to come back near 65%?

Doing this, I see sometimes the EGTs even more decreasing, then increasing again.

I never ever go higher than 65% LOP

 

[Bravoman]

 The focus on these engines is CHTS and TITs. Keeping CHT below 400 at all times, and TIT below 1600. A properly adjusted and baffled bravo engine should run 29/24 in cruise which is about 77% power at 18-18.5 gph with CHTs in the 380 range and a TIT of 1550 or so. That won’t ever hurt this engine IMO.

[dzeleski]

3 hours ago, NicoN said:

@kortopates: Thank you for your information. Extremely interesting.

We have a M20K-231 equipped with an EDM830.

The recommended procedure for lean finding needs to pre-lean the engine to a certain ROP position, then wait and after minutes do the lean-finding.

I tried this procedure pretty often. but always start the leaning pretty soon. as the temperatures are quickly rising! So, now I lean more or less down to 11.5gph, wait only few seconds and then to the lean find procedure. The EDM830 never failed to detect the LOP point. I always further lean to stay between 30 to 70° LOP and end up at 8,2 to 9.5 gph and temperatures max of 365 CHT for #2 and TIT ~1520 (TSIO-360GB).

But, during the Lean-find, the Power decreases from 67% down to ~58%. Is it legal to advance the throttle then to come back near 65%?

Doing this, I see sometimes the EGTs even more decreasing, then increasing again.

I never ever go higher than 65% LOP

 

Check this out: https://www.advancedpilot.com/articles.php?action=article&articleid=1838

Specifically the "Leaner is cooler and cleaner" section. In short yes.

50 degrees ROP is the most dangerous operating condition for any engine, either run at least 80 degrees ROP or run LOP.

At less then 65% power it is impossible to hurt the engine by leaning, higher then 65% power and you need to start paying more attention to what you are doing as you can actually damage things at this power level. I personally wouldnt cruise at anything higher then 75% power. Your engine monitor needs to be calibrated in order for that % power figure to be anywhere near correct however.

The red fin is my favorite representation of how this looks, I stole this from Mike Busch (already linked above) but it does a great job of explaining how you properly use the red knob.

[kortopates]

5 hours ago, NicoN said:

@kortopates: Thank you for your information. Extremely interesting.

We have a M20K-231 equipped with an EDM830.

The recommended procedure for lean finding needs to pre-lean the engine to a certain ROP position, then wait and after minutes do the lean-finding.

I tried this procedure pretty often. but always start the leaning pretty soon. as the temperatures are quickly rising! So, now I lean more or less down to 11.5gph, wait only few seconds and then to the lean find procedure. The EDM830 never failed to detect the LOP point. I always further lean to stay between 30 to 70° LOP and end up at 8,2 to 9.5 gph and temperatures max of 365 CHT for #2 and TIT ~1520 (TSIO-360GB).

But, during the Lean-find, the Power decreases from 67% down to ~58%. Is it legal to advance the throttle then to come back near 65%?

Doing this, I see sometimes the EGTs even more decreasing, then increasing again.

I never ever go higher than 65% LOP

 

Keep in mind that the EDM will never fail to report a peak - but that doesn't mean its accurate. Mixture has to manipulated slowly to get accurate data.

Although I highly recommend using the engine monitor's LF method to learn all about peak, your engines mixture distribution as in your leanest and richest and how your TIT peaks relative to your leanest and richest cylinder peaks. You should understand all this for your engine before moving onto advanced methods of leaning a turbo charged engine.

But doing it slowly at higher power settings is not good for the engine and we really have it easy with a TC engine. We can simply add AIR!

For TC aircraft, rather than the big pull which is my favorite for NA engines, instead I prefer the the big push for TC.

1) At the top of my full power climb, I'll reduce MAP to get a reasonable ROP power setting leaned close to the GPH I need for my target % power setting LOP.   So for example we'll use 68.5% power with 10.5 GPH. I'll reduce MAP and prop to a ROP setting at my target 10.5 GPH for 68.5% LOP. 

2) Next, I'll just add air via MAP. As I do add MAP it will change my mixture (even much more so on the 231) so I'll adjust mixture to maintain my target as I add more add more. We'll see TIT and EGTs go up to peak and then back down onto the lean side.  With a bit of practice I'll have a target MAP value that will be close very quickly, then I'll fine tune for an expected TIT I know should be real close. With enough practice  I am done.

 3) But Verify. Occasionally I'll want to verify; not always but especially if I am trying a different power setting. But to verify with the least risk to the engine, i'll enrich watching for what I already know is my richest cylinder to peak and then without hanging out here,  add mixture back in till my richest EGT is at the target # degrees LOP based on my percent power and the Gami chart I referenced from their AFMS. So per that chart, I need to be 15F LOP when 65-69% power, so I'll set my richest EGT accordingly. Then verify this is my target TIT which I monitor in flight for any changes (its common for it to creep a bit in flight and to keep it always at least 15F LOP, I'll make it a bit leaner (an extra 10F) to give me some buffer). The more recent practice and knowledge I have of my engine numbers the quicker I can set up and have less need to verify regularly.

Its by no means the only or best way but I find it very easy and when in doubt verify. 

[carusoam]

Note the specific red fin representation Posted above is for a NA engine...  similar for TC’d engine with one difference...

the multiple mixture adjustments in the climb will not be required for TC’d engine...

+1 For APS...

+1 For Mr. Bush

+1for @kortopates who is always hanging out on MS, with great detailed support!

Best regards,

-a-

 

[drstephensugiono]

I’m reading all these power settings and I feel very inadequate and uninformed because for 26 years of ownership of the plane I’ve always used power settings of 32/24 @ 19.7 gal/hr with 380-390 CHT, 1550-1580 TIT on my Insight GEM. I fly at that setting 90% of the time thinking it’s about 75-78% power. I thought I flew richer than what my power settings placard says and I was very conservative. What Am I doing incorrectly?


Sent from my iPhone using Tapatalk

[daytonabch04]

I normally fly MAP 28-29, RPM 2300, TIT 1550-1580 and CHT 325-350.  Gets me around 17-18 GPH...No clue what power setting % this is.  I set the JPI 700 on Lean Find ROP and then go -75 from peak.  I need to figure out how to do a GAMI spread check...

[gsxrpilot]

20 minutes ago, daytonabch04 said:

I need to figure out how to do a GAMI spread check...

http://content.savvyanalysis.com/static/pdf/SavvyAnalysisFlightTestProfiles.pdf

[DaveMC]

On ‎03‎/‎07‎/‎2020 at 9:06 PM, kortopates said:

Dave (sorry I used Dan earlier) the max TIT you read and am using was in the context of LOP ops not ROP as you are operating above. The discussion wasn't meant to be focused on a max  TIT, but on needing to stay out of the Red Box; especially as you are learning to lean and experimenting. The size of the red box grows with the % power and is much larger on the ROP side than the LOP. On the ROP side where you are  above, we need to be much richer to be out of it. Using Gami's recommended mixture settings for power settings above 65% to 75% we want to be 100 to 150F ROP from your leanest cylinder and on the LOP side we need only be 15 to 50F LOP on the richest cylinder.  Operating at 29" 2400 rpm, which equates to 81% power per Lycoming Operators Guide, you want to be even a bit more richer and you'd find your TIT will be about 100F lower to be as rich as suggested to do so. Its only on the LOP side, where we are much closer to peak, that we get anywhere near the limits of TIT. At Savvy we recommend a max of 1600F, I personally use 1580F knowing my TIT will creep up periodically closer to 1600F, so 1580 gives me buffer. Whom ever suggested 1600 to a max of 1625F is just operating more aggressively than I do and what we recommend at Savvy but of course your engine won't self destruct at 1601F TIT any more than it will at 1626F - its all about how conservatively or aggressive you want to run it.    

For a more thorough explanation on the Red Box there is a ton of literature by Mike Busch and Deakin on Avweb including a great series. But this article by Mike B https://www.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2012-12_red-box-red-fin.pdf explains the concept really well and really makes the point that using your lean Find mode is not the right way to lean your engine at high power settings like that because you need to go through peak slowly to find it. But you definitely want to learn all about peak and using your engine monitor is very instructive - just don't do it above 65% power since its not good for the engine.  Keep in mind when Mike B says he doesn't necessarily keep track of always care how LOP or ROP his EGTs are its because his cruise is typically no higher than 65% power. He really babies his engines to go 2-3x past TBO. But again his point there is not to rely on using your monitor to slowly find peak and set mixture. 

Additionally, you'll want to learn the specifics of your engine with respect to mixture distribution and probably the health of your ignition system. To do this, I recommend our Savvy Test profile, at http://content.savvyanalysis.com/static/pdf/SavvyAnalysisFlightTestProfiles.pdf  By going through that, you'll not only learn you gami spread but also your leanest and richest cylinders and ranking in between. You want to know your leanest for setting up or verifying ROP mixtures and your richest for LOP ops since you really don't want to have to always use your engine monitor Lean find and go through peak slowly.  

There is a great red box simulator app on the APS site that shows how it size grows with power here https://www.advancedpilot.com/redbox.html

Lastly here is the mixture guidance from GAMI/APS on where to place your mixture for both LOP and ROP that was referenced before: https://gami.com/gamijectors/AFMS - GAMIjectors Rev IR.pdf It doesn't matter whether you have gami's installed or not, its great conservative guidance. 

BTW, hope you're not relying on the % power displayed on your EDM since its indicating 77% power with a power setting rated at ~81% per Lycoming. If that's of value to you, see the calibration procedure in the EDM Pilot Guide. 

Again, since my first post wasn't understood, let me summarize: 

None of this discussion is about how to set mixture or how EDM LF works etc. Its to say that i) using your EDM to set mixture at high power settings is not good for your engine and that ii)at 80% power ROP you want to be much richer because of the red box. But to learn all about these concepts dealing with the Red box, LOP & ROP, using your Engine monitor is excellent way to do it! Just do it at lower safer power settings as you learn - such as the 65% max recommended in our Savvy Test profile. Move up to higher power settings after you learn more about your engine specifics and advanced leaning techniques which get you there faster. Going slowly through peak at what most of us consider the max recommended cruise power setting is not good for the long term health of your engine.

Rather than shoot video's, open a free account on SavvyAnalysis.com, upload your data there and you can share with us on MS by clicking on the share options bottom right (one flight at a time or even all flights). 

so quick question.  if I run LOP for example 25 deg LOP and my TIT is over say 1650 if I lean further to say 50 LOP the TIT should come down? 

[gsxrpilot]

12 minutes ago, DaveMC said:

so quick question.  if I run LOP for example 25 deg LOP and my TIT is over say 1650 if I lean further to say 50 LOP the TIT should come down? 

Yes.

[kortopates]

1 hour ago, DaveMC said:

so quick question.  if I run LOP for example 25 deg LOP and my TIT is over say 1650 if I lean further to say 50 LOP the TIT should come down? 

absolutely, since TIT is merely all 6 EGTs coming together. But it would also be time to reconsider your %power LOP since it might be more beneficial to run at bit lower power and closer to peak than run very deeply LOP (unless we're at a very high power setting) because power drops off very quickly on the LOP. This is something that will take some experimentation on your part and another reason why its helpful to start with no more than 65% power.

[Dsal1]

I run my Bravo at 2200 RPM it is much better on the engine lowers frictional loss and gives more time for gasses to move in and out of cylinder. The prop is also more efficient at the lower RPM. LOP ops work just fine here and allows a higher MP for a given HP rating. Mike Busch also recommends low RPM.