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simple mooney bravo pls power settings


pkofman

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Ok, well I am great risk of over thinking things ,and given I am a sponge for always learning as much as possible about my machine m20m TLS  I have a simple and maybe irrelevant question

Below  is a power chart for the m20m

 I fly my plane at 29/2400 most of the time in cruise

Ive had the plane for 3 years and all is good, but then I just happened to read the chart again and my overthinking went into overdrive!

My power setting seems to give me pretty good numbers and  engine metrics

29/2400  is  not  a power setting I see very often in the mooney literature

Is that a weird combo? It seems to have worked well for me, but perhaps it is not appropriate,  and honestly I never thought about it much because somewhere I read that (53) was a pretty good number. 

Thoughts   

Peter

Screenshot 2019-12-17 08.12.42.png

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Peter, I'm doing the same.  I do not pretend to be an expert in such matters but I do set the MP, RPM and Mixture based on actual engine data and the expertise of other pilots over and above the POH.  I also fly at 29/2400 because as I recall, @donkaye and / or @mike_elliott blessed these numbers. Also, my cylinders stay at or below 380 degrees and TIT of 1550 degrees or below, vibration is minimal and the power output is 75% when ROP or 65% when LOP (roughly).  That chart bothers the heck out of me because it is predicated on peak TIT or 1750 degress F TIT (expect for the best power option).  That parameter alone is troubling enough to toss the whole thing out and start over with real world safety margins.  

Oh, and as an aside, I save 1AMU per month toward the upcoming engine overhaul...my wife insists on it so we will be ready.  I sort of hope that a turbo diesel option will be available when that time comes.

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If you stick to the settings on that chart you will be buying cylinders, turbo chargers and exhaust systems too often. That chart was silk screened on the Pilot's sun visor and was highly influenced by the Mooney marketing department who wanted to squeeze every knot out of the airplane while burning the least fuel possible. Time has shown and Lycoming has confirmed that 1750 TIT should not be used on the TIO-540 engines.

29/24 is the setting I use most often also.

(If you're wondering why you only see Continental engines on Mooney models introduced in the last 26 years, here's one reason . . .  Early TLS airplanes were going through cylinders in a few hundred hours before the Bravo conversion was developed and introduced in 1996. Lycoming, early on,  told Mooney to let owners know to run at a Max of 1650 TIT, not 1750, for better cylinder life. (Lycoming later came out with an engine management booklet for TLS and Piper Mirage owners stating 1650 TIT). 

This affected the 1000 nm range that Mooney was advertising. Then President/CEO Jacques Esculier made it clear to everyone that would listen that the TLS would be the last Mooney developed with a Lycoming engine. He was gone a few years later, but to date there have been no other new Mooneys with a Lycoming.)

 

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Excellent. 2 for 2 and honestly I’m sticking with advice from @donkaye and @mike_elliott two guys who I am aware of who have way more experience and knowledge about these machine than me.  So basically my 29/24 is conservative but I do run it at 1650 as long as CHT is at or below 400.  

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29/2350 is my go to setting with TIT around 1575, I get reasonable performance and fuel flow along with CHT's that are in the 360* range depending on altitude, when just putting around I go as low as 19/2300 getting J performance,  following  the recommended info within the POH will be a costly adventure. A few minutes extra on a trip tends to save enormous money over time.

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5 hours ago, pkofman said:

Excellent. 2 for 2 and honestly I’m sticking with advice from @donkaye and @mike_elliott two guys who I am aware of who have way more experience and knowledge about these machine than me.  So basically my 29/24 is conservative but I do run it at 1650 as long as CHT is at or below 400.  

When you bought your airplane, you should have been provided with the red Lycoming Engine Manual.  There is good information in it.  In case for some reason you don't have it, I've attached relevant engine charts.  In particular see Figures 72, 73, and 74 for Power Settings at various MP and RPM.  I don't believe I ever got an update for the Bravo engine, but it should be the same as the A, since oil injection was the only change.  I think 1650° on the TIT is too hot.  I run a maximum of 1600°-1625°.

Lycoming Charts of the TIO 540AF1A:B Eingine.pdf

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thank you @donkaye. I will review

It is interesting because would have thought that given the 1750 max that 1650 would be conservative

I will run 1625 and see where the temps are

BTW I dont burn much oil in this engine. It pretty good that way and as a matter of consistency I do not lean in the climb,

My typical climb is 34"

But now im going to use the other metric and only reduce power in the climb just to  the point that the boost pump stays on per your earlier comments ( I think I read that somewhere) .I am curious to see what that MP will be at that boost set point.

Peter

 

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16 minutes ago, pkofman said:

thank you @donkaye. I will review

It is interesting because would have thought that given the 1750 max that 1650 would be conservative

I will run 1625 and see where the temps are

BTW I dont burn much oil in this engine. It pretty good that way and as a matter of consistency I do not lean in the climb,

My typical climb is 34"

But now im going to use the other metric and only reduce power in the climb just to  the point that the boost pump stays on per your earlier comments ( I think I read that somewhere) .I am curious to see what that MP will be at that boost set point.

Peter

 

It is my understanding that several people lost their jobs as a result of the 1750° published setting.  It should never have been set that high.  Mooney wanted to get their range up and apparently convinced Lycoming to approve that number.  Maybe 1" of MP is lost when reducing power to turn off the boost pump.  The maximum MP will vary somewhat depending on outside temperature as the result of the density controller.

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Wow that’s interesting.  Did they ever issue a formal amendment to the Poh to cover off that 1750 issue. All of the documentation  I own still has that 1750. But most guys I know with these machines run them way more conservatively 

thanks for the assistance  Pete

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17 minutes ago, pkofman said:

Wow that’s interesting.  Did they ever issue a formal amendment to the Poh to cover off that 1750 issue. All of the documentation  I own still has that 1750. But most guys I know with these machines run them way more conservatively 

thanks for the assistance  Pete

No.

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  • 2 weeks later...

I’ve owned my M20M TLS for more than 25 years. Bought it with 600 hours. I’ve upgraded the cylinder head to the “Bravo” around 1200 hours when they had a special upgrade program. It now has 1700 since new. I’ve run my plane 34/2500 on climb at full rich. Cruise at 32/2400 all day long BUT my fuel setting is 19.7-20.0 gal/hour where I keep things cool. My compressions are excellent in mid 70’s. I don’t follow the leaning guidelines as it scares me to lean it that much. Hope that’s ok, I’d rather spend more on fuel than a rebuild!


Sent from my iPhone using Tapatalk

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