simple mooney bravo pls power settings

[pkofman]

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

[alextstone]

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.

[LANCECASPER]

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.)

 

[pkofman]

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.  

[Danb]

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.

[donkaye]

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

[pkofman]

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

 

[donkaye]

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.

[pkofman]

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

[alextstone]

Just now, pkofman said:

Did they ever issue a formal amendment to the Poh to cover off that 1750 issue.

Admit fault?!?!?  Bahahahaha!

[donkaye]

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.

[Davidv]

I've been running my engine precisely to the specs outlined in the M20M POH, do I have a problem? Shirley, Mooney would pay for the new cylinders since they produced the POH?

</sarcasm>

[alextstone]

Just now, Davidv said:

I've been running my engine precisely to the specs outlined in the M20M POH, do I have a problem? Shirley, Mooney would pay for the new cylinders since they produced the POH?

</sarcasm>

Stop calling me Shirley!

[donkaye]

39 minutes ago, Mark Cline said:

What true airspeeds do you all typically see with 29/2400? 

As you probably already know, it depends on altitude.

[drstephensugiono]

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

[Dammit Bill]

On 12/17/2019 at 2:22 PM, donkaye said:

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 2.27 MB · 74 downloads

Hi Don.
 

I’ve owned my Bravo for about a year and a half and the guidance I have received from members of this group has been invaluable. 53 is the number works for me. I find that 2200 RPM and 31 inches is the sweet spot for my engine. I can get the fuel flow around 14 gallons per hour, TIT of 1600 to 1620 and cylinder head temperatures around 360°. Last week I was seeing true speed of 180 kn with this configuration.
 

I tried to run at 2400 RPM and 29 inches of manifold pressure, I just did not like the way everything was running.

 

I’ve downloaded and looked at the charts that you linked to. I understand what I’m looking at, but I cannot seem to find an adjustment factor for a live peak. They are all based upon maximum power. I come up with about 205 hp at 17,000 feet under conditions I was flying. 75% power. I’d like to know what that is on the side of peak, where my fuel flow is about 4 gallons per hour or less.
 

Would you have any guidance or charts for this adjustment?

 

Thanks

 

Bill

[Jetpilot86]

IIRC, Don does not run peak or LoP, only RoP. 
 

What is your RoP/LoP at your setting based on your engine monitor? At 14gph and running Peak/LoP FF, you should be about 67% power based on the Lean FF chart in the engine manual. Lycoming seems to define Lean FF as Peak TIT/EGT. A parallel Power (ROP) FF would be at least 15.1% higher. CHT’s look good. If you are running LoP, also refer to the Red Box teachings as how much LoP you need to run increases when you try to run higher %HP. 

[donkaye]

3 hours ago, Dammit Bill said:

Hi Don.
 

I’ve owned my Bravo for about a year and a half and the guidance I have received from members of this group has been invaluable. 53 is the number works for me. I find that 2200 RPM and 31 inches is the sweet spot for my engine. I can get the fuel flow around 14 gallons per hour, TIT of 1600 to 1620 and cylinder head temperatures around 360°. Last week I was seeing true speed of 180 kn with this configuration.
 

I tried to run at 2400 RPM and 29 inches of manifold pressure, I just did not like the way everything was running.

 

I’ve downloaded and looked at the charts that you linked to. I understand what I’m looking at, but I cannot seem to find an adjustment factor for a live peak. They are all based upon maximum power. I come up with about 205 hp at 17,000 feet under conditions I was flying. 75% power. I’d like to know what that is on the side of peak, where my fuel flow is about 4 gallons per hour or less.
 

Would you have any guidance or charts for this adjustment?

 

Thanks

 

Bill

For numerous reasons I don't run my engine LOP.  I tried for awhile many years ago, but after expensive exhaust repairs, the inability to get the TIT to behave in a reasonable manner, the lack of smoothness of the engine, and the fact that I didn't buy the airplane to go slow, I chose not to run it LOP.  I've attached a LOP chart for the Bravo, however. 

LOPFFvsHP Bravo.xls

[pkofman]

Hi bill just curious what altitude you are running asn op itline in your post

“I’ve owned my Bravo for about a year and a half and the guidance I have received from members of this group has been invaluable. 53 is the number works for me. I find that 2200 RPM and 31 inches is the sweet spot for my engine. I can get the fuel flow around 14 gallons per hour, TIT of 1600 to 1620 and cylinder head temperatures around 360°. Last week I was seeing true speed of 180 kn with this configuration.”

I genrally run rop 29/2400 (53) in the mid teens i burn around +/-18’s. I keep tit max less then or equal to 1600 and cht less than or max 400.  

I can't recall my exact true but iburn  more than 14 typically
 

If you recall what altitude or was it the 17k outlined in your note. 
 

Peter 

[Dammit Bill]

I generally run 16.5/17.5. 
last week I flew nonstop Ft Worth to Ft Lauderdale. 4:36 TT

2,250 RPM

31” MP

1,610° +/- 10° TIT

Avg CHT 360°

14 GPH

180 kts TAS

Burned 70.1 Gallons

GAMI Injectors

I tried ROP and found that at 18 GPH my CHTs were approaching 400°. Needed to go to 20-21 GPH to keep CHTs below 380° and maybe picked up 15 kts  

I’ve tried to run at 2,400/29" but it seemed rough and struggled to run LOP  

I’m usually looking for range so LOP works for me  

 

Edited January 9 by Dammit Bill
Add GAMIs

[pkofman]

1 hour ago, Dammit Bill said:

I generally run 16.5/17.5. 
last week I flew nonstop Ft Worth to Ft Lauderdale. 4:36 TT

2,250 RPM

31” MP

1,610° +/- 10° TIT

Avg CHT 360°

14 GPH

180 kts TAS

Burned 70.1 Gallons

GAMI Injectors

I tried ROP and found that at 18 GPH my CHTs were approaching 400°. Needed to go to 20-21 GPH to keep CHTs below 380° and maybe picked up 15 kts  

I’ve tried to run at 2,400/29" but it seemed rough and struggled to run LOP  

I’m usually looking for range so LOP works for me  

 

Thanks for the update. Firstly congrats on 4.5 hours. I'd run out of personal constitution before fuel. Thanks for the information.  I do fly my Mooney in a very different way in the mid-teens. It is interesting to me to read about how others use and manage the machine. Peter 

[philiplane]

One overlooked hazard of LOP operations is the wear on the exhaust system. People say EGT's don't matter, which is mostly true at the cylinder, but not in the exhaust system. ROP EGT's might be 1450, and LOP will be 100 degrees hotter. Which translates directly into more thermal stress on the exhaust system. An exhaust system that is expensive on any turbocharged airplane, but even more so on a limited production plane like the Bravo. 

[Fritz1]

concur, the Bravo engine also appears to like lower RPM, I am running 30 " 2300 and TIT is about 15 dF lower for the same TAS and fuel flow compared to 29" 2400, feels like more complete combustion in the cylinder, the Bravo exhaust and intake are not well tuned, the slower it runs, the better, minimum is 2200 RPM. 

[Rick Junkin]

I'm a fan of LOP ops and consistently run my 1989 TLS/Bravo at the same power settings every flight, unless I want to pull it back for sight seeing. I posted this in another thread, repeating it here to offer a different perspective.
 

On the LOP side at 11-12,000’ I see 165-170KTAS at 13.2gph (70%) and 30”/2200RPM. I also have TKS.

For reference, here’s a screen shot of my G3X at 6,000’. Adding 2 KTAS per thousand feet up to 12,000’ the math shows 170KTAS, which of course will vary with OAT/ISA offset.

[hazek]

On 1/9/2025 at 9:46 PM, donkaye said:

I've attached a LOP chart for the Bravo, however. 

Awesome file sir! Do you maybe know who came up with:
 

*Note Note, This formula is a best fit line calculation based on known values of:	
Comp Ratio	FF Multiplier
8.5	14.9
7.5	13.7
7.3	13.53

and how they came up with those?