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millner(at)me.com
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 Posted: Sun Aug 18, 2019 7:11 pm Post subject: Lycoming POH |
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Art Zemon wrflyote:
Executive summary:
· 75% power or greater, run at peak EGT
· less than 75% power, run up to 150 degrees F lean of peak
I think that's kind of scrambled, Art... the engine won't run 150 F lean of peak. What the Lycoming POH refers to is 150 ROP as best power...
Beyond that, running at peak EGT above 65% is not going to have good results...
The wording of the POH is misleading, unfortunately. For instance, Lycoming wrote: Maximum Power Cruise (approximately 75% power) – Never lean beyond 150°F on rich side of peak EGT unless aircraft operator's manual shows otherwise.
So, which way is beyond, leaner or richer? What they mean is do not run leaner than 150 ROP at 75% power or greater. But they do their best to conceal that information.
If you refer to Lycoming SP700, "There are Experts Everywhere" Lycoming explains that their engines can run just fine lean of peak. It's just that Lycoming believes most pilots are too stupid to do so correctly, and so they'll damage their engines... at least , that's what it says in SP700.
So the guidance intended, if we can puzzle our way through the byzantine wording, is that 65% power or less, run anywhere you want, peak is a good place.
Above 65% power, run RICH enough or LEAN enough to keep CHTs below 380 F.
Paul, Talmudic service publication reader mode
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art(at)zemon.name
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| Posted: Mon Aug 19, 2019 4:05 am Post subject: Lycoming POH |
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Thanks for correcting my scrambled interpretation, Paul. Yet another reason why I am sticking to the simple method at 65% of leaning until I experience a loss of power and then enrichening until the engine runs smoothly again. I may not get the absolutely perfectly most optimal fuel flow but my engine seems healthy and I am happy with the gallons per hour (if not the $$$ per gallon).
-- Art Z.
On Sun, Aug 18, 2019 at 10:27 PM Paul Millner <millner(at)me.com (millner(at)me.com)> wrote:
| Quote: |
Art Zemon wrflyote:
Executive summary:
· 75% power or greater, run at peak EGT
· less than 75% power, run up to 150 degrees F lean of peak
I think that's kind of scrambled, Art... the engine won't run 150 F lean of peak. What the Lycoming POH refers to is 150 ROP as best power...
Beyond that, running at peak EGT above 65% is not going to have good results...
The wording of the POH is misleading, unfortunately. For instance, Lycoming wrote: Maximum Power Cruise (approximately 75% power) – Never lean beyond 150°F on rich side of peak EGT unless aircraft operator's manual shows otherwise.
So, which way is beyond, leaner or richer? What they mean is do not run leaner than 150 ROP at 75% power or greater. But they do their best to conceal that information.
If you refer to Lycoming SP700, "There are Experts Everywhere" Lycoming explains that their engines can run just fine lean of peak. It's just that Lycoming believes most pilots are too stupid to do so correctly, and so they'll damage their engines... at least , that's what it says in SP700.
So the guidance intended, if we can puzzle our way through the byzantine wording, is that 65% power or less, run anywhere you want, peak is a good place.
Above 65% power, run RICH enough or LEAN enough to keep CHTs below 380 F.
Paul, Talmudic service publication reader mode
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https://CheerfulCurmudgeon.com/Love the stranger for you yourselves were strangers in Egypt. Deut. 10:19
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Peter(at)sportingaero.com
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| Posted: Mon Aug 19, 2019 2:00 pm Post subject: Lycoming POH |
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I found the articles written by John Deakin in the “Pelican’s Perch” very informative, they used to be on AvWeb but I don’t know if they are still there. They are written for large Continentals, but the concepts are valid on other engines. As Paul has said, above 75% power lean with care as it is possible to get into detonation which can be very poor for the health of your engine and you/your wallet. But above 6000ft most normally aspirated engines won’t pull more than 75%.
Below 75% I lean aggressively to reduce fuel burn – as I live in a land where gas is expensive ($8.50 a gallon – I really wish I hadn’t done that sum…) if I can save a gallon an hour it is attractive. I have found a fuel flow /rpm number where I am happy to leave the engine. It does take some experience with your particular installation to get to know what the numbers are. CHTs are cooler than running ROP for the same airspeed. It does take some care to run LOP safely, start up high in a low workload cruise so it is possible to monitor temperatures closely. Once you have some experience it is possible to run LOP nearly all the time once the initial climbing is done.
Peter
From: owner-aeroelectric-list-server(at)matronics.com <owner-aeroelectric-list-server(at)matronics.com> On Behalf Of Art Zemon
Sent: 19 August 2019 13:03
To: aeroelectric-list(at)matronics.com
Subject: Re: Lycoming POH
Thanks for correcting my scrambled interpretation, Paul. Yet another reason why I am sticking to the simple method at 65% of leaning until I experience a loss of power and then enrichening until the engine runs smoothly again. I may not get the absolutely perfectly most optimal fuel flow but my engine seems healthy and I am happy with the gallons per hour (if not the $$$ per gallon).
-- Art Z.
On Sun, Aug 18, 2019 at 10:27 PM Paul Millner <millner(at)me.com (millner(at)me.com)> wrote:
| Quote: |
Art Zemon wrflyote:
Executive summary:
· 75% power or greater, run at peak EGT
· less than 75% power, run up to 150 degrees F lean of peak
I think that's kind of scrambled, Art... the engine won't run 150 F lean of peak. What the Lycoming POH refers to is 150 ROP as best power...
Beyond that, running at peak EGT above 65% is not going to have good results...
The wording of the POH is misleading, unfortunately. For instance, Lycoming wrote: Maximum Power Cruise (approximately 75% power) – Never lean beyond 150°F on rich side of peak EGT unless aircraft operator's manual shows otherwise.
So, which way is beyond, leaner or richer? What they mean is do not run leaner than 150 ROP at 75% power or greater. But they do their best to conceal that information.
If you refer to Lycoming SP700, "There are Experts Everywhere" Lycoming explains that their engines can run just fine lean of peak. It's just that Lycoming believes most pilots are too stupid to do so correctly, and so they'll damage their engines... at least , that's what it says in SP700.
So the guidance intended, if we can puzzle our way through the byzantine wording, is that 65% power or less, run anywhere you want, peak is a good place.
Above 65% power, run RICH enough or LEAN enough to keep CHTs below 380 F.
Paul, Talmudic service publication reader mode
|
--
https://CheerfulCurmudgeon.com/
Love the stranger for you yourselves were strangers in Egypt. Deut. 10:19
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Kellym
Joined: 10 Jan 2006
Posts: 1700
Location: Sun Lakes AZ
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| Posted: Mon Aug 19, 2019 4:00 pm Post subject: Lycoming POH |
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The articles have been moved a time or two. I believe this is still a
good link:
https://web.archive.org/web/20120119070724/http://www.avweb.com/news/pelican/list.html
On 8/19/2019 2:58 PM, Peter Pengilly wrote:
| Quote: | I found the articles written by John Deakin in the “Pelican’s Perch”
very informative, they used to be on AvWeb but I don’t know if they are
still there. They are written for large Continentals, but the concepts
are valid on other engines. As Paul has said, above 75% power lean with
care as it is possible to get into detonation which can be very poor for
the health of your engine and you/your wallet. But above 6000ft most
normally aspirated engines won’t pull more than 75%.
Below 75% I lean aggressively to reduce fuel burn – as I live in a land
where gas is expensive ($8.50 a gallon – I really wish I hadn’t done
that sum…) if I can save a gallon an hour it is attractive. I have found
a fuel flow /rpm number where I am happy to leave the engine. It does
take some experience with your particular installation to get to know
what the numbers are. CHTs are cooler than running ROP for the same
airspeed. It does take some care to run LOP safely, start up high in a
low workload cruise so it is possible to monitor temperatures closely.
Once you have some experience it is possible to run LOP nearly all the
time once the initial climbing is done.
Peter
*From:*owner-aeroelectric-list-server(at)matronics.com
<owner-aeroelectric-list-server(at)matronics.com> *On Behalf Of *Art Zemon
*Sent:* 19 August 2019 13:03
*To:* aeroelectric-list(at)matronics.com
*Subject:* Re: Lycoming POH
Thanks for correcting my scrambled interpretation, Paul. Yet another
reason why I am sticking to the simple method at 65% of leaning until I
experience a loss of power and then enrichening until the engine runs
smoothly again. I may not get the absolutely perfectly most optimal fuel
flow but my engine seems healthy and I am happy with the gallons per
hour (if not the $$$ per gallon).
-- Art Z.
On Sun, Aug 18, 2019 at 10:27 PM Paul Millner <millner(at)me.com
<mailto:millner(at)me.com>> wrote:
Art Zemon wrflyote:
Executive summary:
· 75% power or greater, run at peak EGT
· less than 75% power, run up to 150 degrees F lean of peak
I think that's kind of scrambled, Art... the engine won't run 150 F
lean of peak. What the Lycoming POH refers to is 150 ROP as best
power...
Beyond that, running at peak EGT above 65% is not going to have good
results...
The wording of the POH is misleading, unfortunately. For instance,
Lycoming wrote: Maximum Power Cruise (approximately 75% power) –
Never lean beyond 150°F on rich side of peak EGT unless aircraft
operator's manual shows otherwise.
So, which way is beyond, leaner or richer? What they mean is do not
run leaner than 150 ROP at 75% power or greater. But they do their
best to conceal that information.
If you refer to Lycoming SP700, "There are Experts Everywhere"
Lycoming explains that their engines can run just fine lean of peak.
It's just that Lycoming believes most pilots are too stupid to do so
correctly, and so they'll damage their engines... at least , that's
what it says in SP700.
So the guidance intended, if we can puzzle our way through the
byzantine wording, is that 65% power or less, run anywhere you want,
peak is a good place.
Above 65% power, run RICH enough or LEAN enough to keep CHTs below
380 F.
Paul, Talmudic service publication reader mode
--
https://CheerfulCurmudgeon.com/
/Love the stranger for you yourselves were strangers in Egypt. /Deut. 10:19
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
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