Matronics Email Lists :: View topic - Lean of Peak and other heresies

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Lean of Peak and other heresies

Matronics Email Lists Forum Index -> RV10-List

View previous topic :: View next topic

Author Message

kearney

Joined: 20 Sep 2008
Posts: 563

Posted: Mon Aug 11, 2014 5:14 pm Post subject: Lean of Peak and other heresies

Hi



At KOSH I received some very conflicted info on lean of peak ops with an IO540. 



Continental (admittedly not a Lyc IO540), had a wonderful simulation / presentation about how to safely run LOP. Their position was to stay under 65% power to avoid the "red Box". 



Lycoming seemed to think that LOP was was a high risk venture that most mere mortals should avoid like the plague. They even has a 2000 monograph that had a few veiled references to Gami.



Mike Busch was very much in support of LOP ops in either brand C or L engines. His view was physics doesnt't change with the brand of engine.



So, given that we have now resolved how to properly prime lithium batteries, I would be interested in hearing about first hand LOP experiences. Has anyone experienced problems with LOP. Lycoming seems to think that LOP requires more attention to detail than the average pilot can muster when things busy. They also suggest that ROP at power settings that match LOP power yields similar albeit somewhat higher fuel flows. Does actual experience bear this out?



Any comments?



Cheers



Les

Inquiring minds need to know!

rv10flyer(at)live.com
Guest

Posted: Mon Aug 11, 2014 5:48 pm Post subject: Lean of Peak and other heresies

Plainly put the lycoming rep was uneducated on the Lycoming stance:

 http://www.avweb.com/news/maint/182849-1.html?redirected=1

 Lie #7:

 Aggressive leaning results in burned valves and detonation.

  

 Fear of the red knob is one of the most pernicious areas of misinformation  among general aviation pilots. Most pilots operate way too rich most of the  time, and do so because of the mistaken belief that leaning will harm their  engine. The result is usually trouble: fouled spark plugs, accelerated exhaust  valve guide wear, and stuck exhaust valves.

  

 Lycoming engine Lycoming has long authorized leaning to peak EGT at any  cruise setting up to 75% power. TCM authorizes leaning to peak EGT up to 65%,  and its latest recommendations even endorse lean-of-peak operation for many  big-bore engines, provided the engines will run smoothly when operated that  lean.

  

 Contrary to popular belief, aggressive leaning doesn't cause burned valves.  Most burned valves are the result of excessive valve guide wear or valve stem  contamination.

  

 Aggressive leaning doesn't cause detonation, either. Most of our engines  are incapable of detonation at cruise power settings, provided that we don't  exceed CHT red-line or try to burn contaminated fuel. Furthermore, recent tests  on Lycoming engines by ASTM revealed this fascinating result: detonation is most  likely to occur at a mixture setting 11% richer than stoichiometric (i.e.,  substantially richer than peak EGT).

  

 Lean as aggressively as the book allows. For Lycomings, that means peak EGT  at all cruise power settings to 75%. For Continentals, lean to peak EGT up to  65%, 50Â°F rich of peak at 75%. For turbocharged engines, also limit TIT to  1600Â°F.

  

 Lean during all ground operations except for engine start. It is  particularly important to lean for taxi and runup. Since EGT is usually  off-scale at idle power, the best method is to lean for peak RPM at idle. 

  

 Read through Lycomingâ€™s Key Operations- found on the lycoming site. Plenty  about leaning at 75% and lower and even a chart that says they do not recommend  LOP, but on the same page has: 

 pg38

 6. Leaning to best economy mixture.

 a. Set manifold pressure and RPM for the desired cruise power setting per  the aircraft POH/AFM.

 b. Lean slowly in small steps, while monitoring instrumentation, to peak  TIT or maximum allowable TIT, whichever occurs first

 [img]cid:3B93739FEA40497897A78D3550E4E0BE(at)pascalPC[/img]

  

 than on pg 39:

 Once cruise power has been set, leaning to best economy should be standard  procedure as damage to the engine will not occur from leaning at cruise power  settings.

  

  

 --

image[3].png

Description:

Filesize:

141.62 KB

Viewed:

10464 Time(s)

gengrumpy

Joined: 07 May 2013
Posts: 131
Location: Tullahoma, TN

Posted: Mon Aug 11, 2014 5:50 pm Post subject: Lean of Peak and other heresies

Les,



I've been using Mike Busch's techniques with my Lyc IO540 and they work just great.  My CHTs typically run 300 - 340 max or so at 65% and LOP, and are lower when I run less than 65% power.



I make the "big pull" to lean it out thus not spending any time in the "Red Box".



Fuel flows for me are typically 11 - 11.5gph at 65% power and that gives me (at)150KTAS in the 5 - 9k range.



Mike knows his stuff, and I just recently changed to a paid subscription on his website after hearing him talk about his new analysis capability for detecting early exhaust valve failures.  



His website for uploading your data is an outstanding diagnostic tool, and beats the propriety program I have been using for years.



grumpy



do not archive



On Aug 11, 2014, at 8:09 PM, LES KEARNEY <kearney(at)shaw.ca> wrote:



 	  Quote: 	
		   

 

 Hi

 

 At KOSH I received some very conflicted info on lean of peak ops with an IO540. 

 

 Continental (admittedly not a Lyc IO540), had a wonderful simulation / presentation about how to safely run LOP. Their position was to stay under 65% power to avoid the "red Box". 

 

 Lycoming seemed to think that LOP was was a high risk venture that most mere mortals should avoid like the plague. They even has a 2000 monograph that had a few veiled references to Gami.

 

 Mike Busch was very much in support of LOP ops in either brand C or L engines. His view was physics doesnt't change with the brand of engine.

 

 So, given that we have now resolved how to properly prime lithium batteries, I would be interested in hearing about first hand LOP experiences. Has anyone experienced problems with LOP. Lycoming seems to think that LOP requires more attention to detail than the average pilot can muster when things busy. They also suggest that ROP at power settings that match LOP power yields similar albeit somewhat higher fuel flows. Does actual experience bear this out?

 

 Any comments?

 

 Cheers

 

 Les

 Inquiring minds need to know!

kearney

Joined: 20 Sep 2008
Posts: 563

Posted: Mon Aug 11, 2014 6:19 pm Post subject: Lean of Peak and other heresies

Hi Pascal

Here is a link to the monograph I hot from Lycoming at KOSH. 

http://www.shamrockairservices.com/images/LEANING%20TECHNIQUES.pdf

Cheers

Les



Sent from my iPhone



On Aug 11, 2014, at 7:43 PM, "Pascal" <rv10flyer(at)live.com (rv10flyer(at)live.com)> wrote:

[quote]    Plainly put the lycoming rep was uneducated on the Lycoming stance:

 http://www.avweb.com/news/maint/182849-1.html?redirected=1

 Lie #7:

 Aggressive leaning results in burned valves and detonation.

  

 Fear of the red knob is one of the most pernicious areas of misinformation  among general aviation pilots. Most pilots operate way too rich most of the  time, and do so because of the mistaken belief that leaning will harm their  engine. The result is usually trouble: fouled spark plugs, accelerated exhaust  valve guide wear, and stuck exhaust valves.

  

 Lycoming engine Lycoming has long authorized leaning to peak EGT at any  cruise setting up to 75% power. TCM authorizes leaning to peak EGT up to 65%,  and its latest recommendations even endorse lean-of-peak operation for many  big-bore engines, provided the engines will run smoothly when operated that  lean.

  

 Contrary to popular belief, aggressive leaning doesn't cause burned valves.  Most burned valves are the result of excessive valve guide wear or valve stem  contamination.

  

 Aggressive leaning doesn't cause detonation, either. Most of our engines  are incapable of detonation at cruise power settings, provided that we don't  exceed CHT red-line or try to burn contaminated fuel. Furthermore, recent tests  on Lycoming engines by ASTM revealed this fascinating result: detonation is most  likely to occur at a mixture setting 11% richer than stoichiometric (i.e.,  substantially richer than peak EGT).

  

 Lean as aggressively as the book allows. For Lycomings, that means peak EGT  at all cruise power settings to 75%. For Continentals, lean to peak EGT up to  65%, 50Â°F rich of peak at 75%. For turbocharged engines, also limit TIT to  1600Â°F.

  

 Lean during all ground operations except for engine start. It is  particularly important to lean for taxi and runup. Since EGT is usually  off-scale at idle power, the best method is to lean for peak RPM at idle. 

  

 Read through Lycomingâ€™s Key Operations- found on the lycoming site. Plenty  about leaning at 75% and lower and even a chart that says they do not recommend  LOP, but on the same page has: 

 pg38

 6. Leaning to best economy mixture.

 a. Set manifold pressure and RPM for the desired cruise power setting per  the aircraft POH/AFM.

 b. Lean slowly in small steps, while monitoring instrumentation, to peak  TIT or maximum allowable TIT, whichever occurs first

 <image[3].png>

  

 than on pg 39:

 Once cruise power has been set, leaning to best economy should be standard  procedure as damage to the engine will not occur from leaning at cruise power  settings.

  

  

 --

Bob Turner

Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA

Posted: Mon Aug 11, 2014 6:31 pm Post subject: Re: Lean of Peak and other heresies

In no particular order:

1. I do not attempt to operate LOP at high power settings. I think my injectors aren't tuned well enough to get all the cylinders out of the red box at high powers.

2. I did have to tune the injectors. Stock setup was not great in that regard.

3. Typical cruise for me is at 11,000'; all cylinders 10 to 30 F LOP; wide open throttle; 2200-2300 RPM; 9.5 gal/hr fuel flow; 160 KTAS. CHT's are 325 F plus or minus 10F or so (I removed the front air dams). This is two people plus bags. Full gross and I lose a couple of knots.

_________________
Bob Turner
RV-10 QB

rv10flyer(at)live.com
Guest

Posted: Mon Aug 11, 2014 6:49 pm Post subject: Lean of Peak and other heresies

Funny thy tell folks to avoid when they have this to support just the  opposite.

  

 To answer you questions, I always fly LOP, I tuned the injectors and can  get the plane to fly smoothly at around the 9.8-10.2gph range. Every annual has  shown a very clean and good looking cylinder. The A&P that does the scope  says itâ€™s the cleanest cylinder he sees all year. He cant believe its because I  fly LOP, but knows the certs he sees are flying ROP because of carbs or POH  instructions to be 50-100F ROP, and is starting to believe that the 75F LOP I  usually see is the reason for the cleaner inspections.

 I have about 300hrs on the narrow deck / eci cylinders and LOP works very  well for my CHT temps. I do not fly ROP ever (except TO and initial climb),  pretty much from 1K up I have the aircraft leaned.

 Pascal

    

  From: Les Kearney (kearney(at)shaw.ca) 

 Sent: Monday, August 11, 2014 7:18 PM

 To: rv10-list(at)matronics.com (rv10-list(at)matronics.com) 

 Subject: Re: Lean of Peak and other  heresies

  



  Hi Pascal

  

 Here is a link to the monograph I hot from Lycoming at KOSH. 

  

 http://www.shamrockairservices.com/images/LEANING%20TECHNIQUES.pdf

  

 Cheers

  

 Les



Sent from my iPhone

 

On Aug 11, 2014, at 7:43 PM, "Pascal" <rv10flyer(at)live.com (rv10flyer(at)live.com)> wrote:

 [quote]            Plainly put the lycoming rep was uneducated on the Lycoming stance:

   http://www.avweb.com/news/maint/182849-1.html?redirected=1

   Lie #7:

   Aggressive leaning results in burned valves and detonation.

    

   Fear of the red knob is one of the most pernicious areas of    misinformation among general aviation pilots. Most pilots operate way too rich    most of the time, and do so because of the mistaken belief that leaning will    harm their engine. The result is usually trouble: fouled spark plugs,    accelerated exhaust valve guide wear, and stuck exhaust valves.

    

   Lycoming engine Lycoming has long authorized leaning to peak EGT at any    cruise setting up to 75% power. TCM authorizes leaning to peak EGT up to 65%,    and its latest recommendations even endorse lean-of-peak operation for many    big-bore engines, provided the engines will run smoothly when operated that    lean.

    

   Contrary to popular belief, aggressive leaning doesn't cause burned    valves. Most burned valves are the result of excessive valve guide wear or    valve stem contamination.

    

   Aggressive leaning doesn't cause detonation, either. Most of our engines    are incapable of detonation at cruise power settings, provided that we don't    exceed CHT red-line or try to burn contaminated fuel. Furthermore, recent    tests on Lycoming engines by ASTM revealed this fascinating result: detonation    is most likely to occur at a mixture setting 11% richer than stoichiometric    (i.e., substantially richer than peak EGT).

    

   Lean as aggressively as the book allows. For Lycomings, that means peak    EGT at all cruise power settings to 75%. For Continentals, lean to peak EGT up    to 65%, 50Â°F rich of peak at 75%. For turbocharged engines, also limit TIT to    1600Â°F.

    

   Lean during all ground operations except for engine start. It is    particularly important to lean for taxi and runup. Since EGT is usually    off-scale at idle power, the best method is to lean for peak RPM at idle.    

    

   Read through Lycomingâ€™s Key Operations- found on the lycoming site.    Plenty about leaning at 75% and lower and even a chart that says they do not    recommend LOP, but on the same page has: 

   pg38

   6. Leaning to best economy mixture.

   a. Set manifold pressure and RPM for the desired cruise power setting per    the aircraft POH/AFM.

   b. Lean slowly in small steps, while monitoring instrumentation, to peak    TIT or maximum allowable TIT, whichever occurs first

   <image[3].png>

    

   than on pg 39:

   Once cruise power has been set, leaning to best economy should be    standard procedure as damage to the engine will not occur from leaning at    cruise power settings.

    

    

   --

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Mon Aug 11, 2014 6:54 pm Post subject: Lean of Peak and other heresies

Pascal has it right. Lycoming says you are too inattentive, too dumb and basically incapable of operating lean of peak because a. their engineers have never tried it

 

b. their engineers are too stupid to understand it



c. their lawyers perceive a little itty bitty risk that must be avoided



d. they wouldn't want to change from what they recommended 50 yrs ago.

 

I've operated my 200 hp Lycoming IO-360-A1A LOP for the past 12 yrs or 700 hours without a problem.  Prior to that it had some valve sticking that probably caused overload on the cam lobes that resulted in spalled cam lobes and lifters. It is stock 8.7:1 compression requiring 100 octane minimum...closer to detonation margin than an stock IO-540 260 hp at 8.5:1 compression.

 

The main thing is to understand that you have one reference point for ROP (when the first cylinder peaks) and LOP (when the LAST cylinder peaks). I normally run full throttle and 10-20 LOP anywhere above 6000 ft (~24" MAP). Fuel consumption will be about 0.5 gph per cylinder less than same power ROP.

 

75% for IO-540=195hp = ~13gph LOP.



65%=169hp=~11.3 gph



for normally aspirated engines between 8.5 and 8.7 to 1 compression when LOP power=FF*15  (14.9 if you want that much precision)



 



On Mon, Aug 11, 2014 at 7:18 PM, Les Kearney <kearney(at)shaw.ca (kearney(at)shaw.ca)> wrote:

[quote] Hi Pascal

Here is a link to the monograph I hot from Lycoming at KOSH. 

http://www.shamrockairservices.com/images/LEANING%20TECHNIQUES.pdf

 



Cheers

Les



Sent from my iPhone



On Aug 11, 2014, at 7:43 PM, "Pascal" <rv10flyer(at)live.com (rv10flyer(at)live.com)> wrote:

 

[quote]    Plainly put the lycoming rep was uneducated on the Lycoming stance:

 http://www.avweb.com/news/maint/182849-1.html?redirected=1

 Lie #7:

 Aggressive leaning results in burned valves and detonation.

  

 Fear of the red knob is one of the most pernicious areas of misinformation  among general aviation pilots. Most pilots operate way too rich most of the  time, and do so because of the mistaken belief that leaning will harm their  engine. The result is usually trouble: fouled spark plugs, accelerated exhaust  valve guide wear, and stuck exhaust valves.

  

 Lycoming engine Lycoming has long authorized leaning to peak EGT at any  cruise setting up to 75% power. TCM authorizes leaning to peak EGT up to 65%,  and its latest recommendations even endorse lean-of-peak operation for many  big-bore engines, provided the engines will run smoothly when operated that  lean.

  

 Contrary to popular belief, aggressive leaning doesn't cause burned valves.  Most burned valves are the result of excessive valve guide wear or valve stem  contamination.

  

 Aggressive leaning doesn't cause detonation, either. Most of our engines  are incapable of detonation at cruise power settings, provided that we don't  exceed CHT red-line or try to burn contaminated fuel. Furthermore, recent tests  on Lycoming engines by ASTM revealed this fascinating result: detonation is most  likely to occur at a mixture setting 11% richer than stoichiometric (i.e.,  substantially richer than peak EGT).

  

 Lean as aggressively as the book allows. For Lycomings, that means peak EGT  at all cruise power settings to 75%. For Continentals, lean to peak EGT up to  65%, 50°F rich of peak at 75%. For turbocharged engines, also limit TIT to  1600°F.

  

 Lean during all ground operations except for engine start. It is  particularly important to lean for taxi and runup. Since EGT is usually  off-scale at idle power, the best method is to lean for peak RPM at idle. 

  

 Read through Lycoming&rsquo;s Key Operations- found on the lycoming site. Plenty  about leaning at 75% and lower and even a chart that says they do not recommend  LOP, but on the same page has: 

 pg38

 6. Leaning to best economy mixture.

 a. Set manifold pressure and RPM for the desired cruise power setting per  the aircraft POH/AFM.

 b. Lean slowly in small steps, while monitoring instrumentation, to peak  TIT or maximum allowable TIT, whichever occurs first

 

<image[3].png>

  

 than on pg 39:

 Once cruise power has been set, leaning to best economy should be standard  procedure as damage to the engine will not occur from leaning at cruise power  settings.

  

  

 --

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Mon Aug 11, 2014 6:56 pm Post subject: Lean of Peak and other heresies

I'm assuming it is fuel economy that motivates your operating at 55% power LOP? Absolutely nothing wrong with it, and excellent speed for that power.



 On Mon, Aug 11, 2014 at 7:31 PM, Bob Turner <bobturner(at)alum.rpi.edu (bobturner(at)alum.rpi.edu)> wrote:

[quote] --> RV10-List message posted by: "Bob Turner" <bobturner(at)alum.rpi.edu (bobturner(at)alum.rpi.edu)>

 

 In no particular order:

 1. I do not attempt to operate LOP at high power settings. I think my injectors aren't tuned well enough to get all the cylinders out of the red box at high powers.

 2. I did have to tune the injectors. Stock setup was not great in that regard.

 3. Typical cruise for me is at 11,000'; all cylinders 10 to 30 F LOP; wide open throttle; 2200-2300 RPM; 9.5 gal/hr fuel flow; 160 KTAS. CHT's are 325 F plus or minus 10F or so (I removed the front air dams). This is two people plus bags. Full gross and I lose a couple of knots.

  

 --------

 Bob Turner

 RV-10 QB

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=428328#428328

 

 

 

 

 

 

 

 ===========

 arget="_blank">http://www.matronics.com/Navigator?RV10-List

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 [b]

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD

kearney

Joined: 20 Sep 2008
Posts: 563

Posted: Mon Aug 11, 2014 7:22 pm Post subject: Lean of Peak and other heresies

Hmmm

Has anyone run LOP with 9:1 compression cylinders?

For the IO540, is there a power setting analogous to the Brand C 65% power setting that eliminates the red box risk?

Cheers

Les



Sent from my iPhone



On Aug 11, 2014, at 8:53 PM, Kelly McMullen <apilot2(at)gmail.com (apilot2(at)gmail.com)> wrote:

[quote]Pascal has it right. Lycoming says you are too inattentive, too dumb and basically incapable of operating lean of peak because a. their engineers have never tried it

 

b. their engineers are too stupid to understand it



c. their lawyers perceive a little itty bitty risk that must be avoided



d. they wouldn't want to change from what they recommended 50 yrs ago.

 

I've operated my 200 hp Lycoming IO-360-A1A LOP for the past 12 yrs or 700 hours without a problem.  Prior to that it had some valve sticking that probably caused overload on the cam lobes that resulted in spalled cam lobes and lifters. It is stock 8.7:1 compression requiring 100 octane minimum...closer to detonation margin than an stock IO-540 260 hp at 8.5:1 compression.

 

The main thing is to understand that you have one reference point for ROP (when the first cylinder peaks) and LOP (when the LAST cylinder peaks). I normally run full throttle and 10-20 LOP anywhere above 6000 ft (~24" MAP). Fuel consumption will be about 0.5 gph per cylinder less than same power ROP.

 

75% for IO-540=195hp = ~13gph LOP.



65%=169hp=~11.3 gph



for normally aspirated engines between 8.5 and 8.7 to 1 compression when LOP power=FF*15  (14.9 if you want that much precision)



 



On Mon, Aug 11, 2014 at 7:18 PM, Les Kearney <kearney(at)shaw.ca (kearney(at)shaw.ca)> wrote:

[quote] Hi Pascal

Here is a link to the monograph I hot from Lycoming at KOSH. 

http://www.shamrockairservices.com/images/LEANING%20TECHNIQUES.pdf

 



Cheers

Les



Sent from my iPhone



On Aug 11, 2014, at 7:43 PM, "Pascal" <rv10flyer(at)live.com (rv10flyer(at)live.com)> wrote:

 

[quote]    Plainly put the lycoming rep was uneducated on the Lycoming stance:

 http://www.avweb.com/news/maint/182849-1.html?redirected=1

 Lie #7:

 Aggressive leaning results in burned valves and detonation.

  

 Fear of the red knob is one of the most pernicious areas of misinformation  among general aviation pilots. Most pilots operate way too rich most of the  time, and do so because of the mistaken belief that leaning will harm their  engine. The result is usually trouble: fouled spark plugs, accelerated exhaust  valve guide wear, and stuck exhaust valves.

  

 Lycoming engine Lycoming has long authorized leaning to peak EGT at any  cruise setting up to 75% power. TCM authorizes leaning to peak EGT up to 65%,  and its latest recommendations even endorse lean-of-peak operation for many  big-bore engines, provided the engines will run smoothly when operated that  lean.

  

 Contrary to popular belief, aggressive leaning doesn't cause burned valves.  Most burned valves are the result of excessive valve guide wear or valve stem  contamination.

  

 Aggressive leaning doesn't cause detonation, either. Most of our engines  are incapable of detonation at cruise power settings, provided that we don't  exceed CHT red-line or try to burn contaminated fuel. Furthermore, recent tests  on Lycoming engines by ASTM revealed this fascinating result: detonation is most  likely to occur at a mixture setting 11% richer than stoichiometric (i.e.,  substantially richer than peak EGT).

  

 Lean as aggressively as the book allows. For Lycomings, that means peak EGT  at all cruise power settings to 75%. For Continentals, lean to peak EGT up to  65%, 50Â°F rich of peak at 75%. For turbocharged engines, also limit TIT to  1600Â°F.

  

 Lean during all ground operations except for engine start. It is  particularly important to lean for taxi and runup. Since EGT is usually  off-scale at idle power, the best method is to lean for peak RPM at idle. 

  

 Read through Lycomingâ€™s Key Operations- found on the lycoming site. Plenty  about leaning at 75% and lower and even a chart that says they do not recommend  LOP, but on the same page has: 

 pg38

 6. Leaning to best economy mixture.

 a. Set manifold pressure and RPM for the desired cruise power setting per  the aircraft POH/AFM.

 b. Lean slowly in small steps, while monitoring instrumentation, to peak  TIT or maximum allowable TIT, whichever occurs first

 

<image[3].png>

  

 than on pg 39:

 Once cruise power has been set, leaning to best economy should be standard  procedure as damage to the engine will not occur from leaning at cruise power  settings.

  

  

 --

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Mon Aug 11, 2014 7:48 pm Post subject: Lean of Peak and other heresies

Les,

Just curious why you would want 9:1 compression when the availability of

true 100 octane fuel into the future is questionable?

The gain in horsepower might help a little on really short or high

elevation airports, but it isn't going to do much for cruise speed.

I don't know anyone that thinks the acceleration and climb of the stock 260

is inadequate for most any normal operation.

The physics is the same. 8.7:1 has almost zero red box and 8.5 to 1 even

less. Higher compression just means the red box is bigger and needs more

attention, just like a turbo would.

On Mon, Aug 11, 2014 at 8:21 PM, Les Kearney <kearney(at)shaw.ca> wrote:



[quote] Hmmm



 Has anyone run LOP with 9:1 compression cylinders?



 For the IO540, is there a power setting analogous to the Brand C 65% power

 setting that eliminates the red box risk?



 Cheers



 Les



 Sent from my iPhone



 On Aug 11, 2014, at 8:53 PM, Kelly McMullen <apilot2(at)gmail.com> wrote:



 Pascal has it right. Lycoming says you are too inattentive, too dumb and

 basically incapable of operating lean of peak because a. their engineers

 have never tried it

 b. their engineers are too stupid to understand it

 c. their lawyers perceive a little itty bitty risk that must be avoided

 d. they wouldn't want to change from what they recommended 50 yrs ago.

 I've operated my 200 hp Lycoming IO-360-A1A LOP for the past 12 yrs or 700

 hours without a problem.  Prior to that it had some valve sticking that

 probably caused overload on the cam lobes that resulted in spalled cam

 lobes and lifters. It is stock 8.7:1 compression requiring 100 octane

 minimum...closer to detonation margin than an stock IO-540 260 hp at 8.5:1

 compression.

 The main thing is to understand that you have one reference point for ROP

 (when the first cylinder peaks) and LOP (when the LAST cylinder peaks). I

 normally run full throttle and 10-20 LOP anywhere above 6000 ft (~24" MAP).

 Fuel consumption will be about 0.5 gph per cylinder less than same power

 ROP.

 75% for IO-540=195hp = ~13gph LOP.

 65%=169hp=~11.3 gph

 for normally aspirated engines between 8.5 and 8.7 to 1 compression when

 LOP power=FF*15  (14.9 if you want that much precision)

 On Mon, Aug 11, 2014 at 7:18 PM, Les Kearney <kearney(at)shaw.ca> wrote:



> Hi Pascal

>

> Here is a link to the monograph I hot from Lycoming at KOSH.

>

> http://www.shamrockairservices.com/images/LEANING%20TECHNIQUES.pdf

>

> Cheers

>

> Les

>

> Sent from my iPhone

>

> On Aug 11, 2014, at 7:43 PM, "Pascal" <rv10flyer(at)live.com> wrote:

>

>  Plainly put the lycoming rep was uneducated on the Lycoming stance:

> http://www.avweb.com/news/maint/182849-1.html?redirected=1

> Lie #7:

> Aggressive leaning results in burned valves and detonation.

>

> Fear of the red knob is one of the most pernicious areas of

> misinformation among general aviation pilots. Most pilots operate way too

> rich most of the time, and do so because of the mistaken belief that

> leaning will harm their engine. The result is usually trouble: fouled spark

> plugs, accelerated exhaust valve guide wear, and stuck exhaust valves.

>

> Lycoming engine Lycoming has long authorized leaning to peak EGT at any

> cruise setting up to 75% power. TCM authorizes leaning to peak EGT up to

> 65%, and its latest recommendations even endorse lean-of-peak operation for

> many big-bore engines, provided the engines will run smoothly when operated

> that lean.

>

> Contrary to popular belief, aggressive leaning doesn't cause burned

> valves. Most burned valves are the result of excessive valve guide wear or

> valve stem contamination.

>

> Aggressive leaning doesn't cause detonation, either. Most of our engines

> are incapable of detonation at cruise power settings, provided that we

> don't exceed CHT red-line or try to burn contaminated fuel. Furthermore,

> recent tests on Lycoming engines by ASTM revealed this fascinating result:

> detonation is most likely to occur at a mixture setting 11% richer than

> stoichiometric (i.e., substantially richer than peak EGT).

>

> Lean as aggressively as the book allows. For Lycomings, that means peak

> EGT at all cruise power settings to 75%. For Continentals, lean to peak EGT

> up to 65%, 50°F rich of peak at 75%. For turbocharged engines, also limit

> TIT to 1600°F.

>

> Lean during all ground operations except for engine start. It is

> particularly important to lean for taxi and runup. Since EGT is usually

> off-scale at idle power, the best method is to lean for peak RPM at idle

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD

jesse(at)saintaviation.co
Guest

Posted: Mon Aug 11, 2014 7:48 pm Post subject: Lean of Peak and other heresies

This is right on based on my experience as well. Our -10 has over 1,300 hrs on ECI narrow deck cylinders running LOP exactly as Pascal describes. Tuned injectors help. Some engines can't even get LOP smoothly without them. Some do, but it helps in all cases. That is why I started stocking the AFP restrictors. I recommend it to everybody I can. It's nice to be able to avoid the Gami prices with our experimentals. 



Jesse Saint

Saint Aviation, Inc.

352-427-0285

jesse(at)saintaviation.com (jesse(at)saintaviation.com)

Sent from my iPad



On Aug 11, 2014, at 10:53 PM, Kelly McMullen <apilot2(at)gmail.com (apilot2(at)gmail.com)> wrote:

[quote]Pascal has it right. Lycoming says you are too inattentive, too dumb and basically incapable of operating lean of peak because a. their engineers have never tried it

 

b. their engineers are too stupid to understand it



c. their lawyers perceive a little itty bitty risk that must be avoided



d. they wouldn't want to change from what they recommended 50 yrs ago.

 

I've operated my 200 hp Lycoming IO-360-A1A LOP for the past 12 yrs or 700 hours without a problem.  Prior to that it had some valve sticking that probably caused overload on the cam lobes that resulted in spalled cam lobes and lifters. It is stock 8.7:1 compression requiring 100 octane minimum...closer to detonation margin than an stock IO-540 260 hp at 8.5:1 compression.

 

The main thing is to understand that you have one reference point for ROP (when the first cylinder peaks) and LOP (when the LAST cylinder peaks). I normally run full throttle and 10-20 LOP anywhere above 6000 ft (~24" MAP). Fuel consumption will be about 0.5 gph per cylinder less than same power ROP.

 

75% for IO-540=195hp = ~13gph LOP.



65%=169hp=~11.3 gph



for normally aspirated engines between 8.5 and 8.7 to 1 compression when LOP power=FF*15  (14.9 if you want that much precision)



 



On Mon, Aug 11, 2014 at 7:18 PM, Les Kearney <kearney(at)shaw.ca (kearney(at)shaw.ca)> wrote:

[quote] Hi Pascal

Here is a link to the monograph I hot from Lycoming at KOSH. 

http://www.shamrockairservices.com/images/LEANING%20TECHNIQUES.pdf

 



Cheers

Les



Sent from my iPhone



On Aug 11, 2014, at 7:43 PM, "Pascal" <rv10flyer(at)live.com (rv10flyer(at)live.com)> wrote:

 

[quote]    Plainly put the lycoming rep was uneducated on the Lycoming stance:

 http://www.avweb.com/news/maint/182849-1.html?redirected=1

 Lie #7:

 Aggressive leaning results in burned valves and detonation.

  

 Fear of the red knob is one of the most pernicious areas of misinformation  among general aviation pilots. Most pilots operate way too rich most of the  time, and do so because of the mistaken belief that leaning will harm their  engine. The result is usually trouble: fouled spark plugs, accelerated exhaust  valve guide wear, and stuck exhaust valves.

  

 Lycoming engine Lycoming has long authorized leaning to peak EGT at any  cruise setting up to 75% power. TCM authorizes leaning to peak EGT up to 65%,  and its latest recommendations even endorse lean-of-peak operation for many  big-bore engines, provided the engines will run smoothly when operated that  lean.

  

 Contrary to popular belief, aggressive leaning doesn't cause burned valves.  Most burned valves are the result of excessive valve guide wear or valve stem  contamination.

  

 Aggressive leaning doesn't cause detonation, either. Most of our engines  are incapable of detonation at cruise power settings, provided that we don't  exceed CHT red-line or try to burn contaminated fuel. Furthermore, recent tests  on Lycoming engines by ASTM revealed this fascinating result: detonation is most  likely to occur at a mixture setting 11% richer than stoichiometric (i.e.,  substantially richer than peak EGT).

  

 Lean as aggressively as the book allows. For Lycomings, that means peak EGT  at all cruise power settings to 75%. For Continentals, lean to peak EGT up to  65%, 50Â°F rich of peak at 75%. For turbocharged engines, also limit TIT to  1600Â°F.

  

 Lean during all ground operations except for engine start. It is  particularly important to lean for taxi and runup. Since EGT is usually  off-scale at idle power, the best method is to lean for peak RPM at idle. 

  

 Read through Lycomingâ€™s Key Operations- found on the lycoming site. Plenty  about leaning at 75% and lower and even a chart that says they do not recommend  LOP, but on the same page has: 

 pg38

 6. Leaning to best economy mixture.

 a. Set manifold pressure and RPM for the desired cruise power setting per  the aircraft POH/AFM.

 b. Lean slowly in small steps, while monitoring instrumentation, to peak  TIT or maximum allowable TIT, whichever occurs first

 

<image[3].png>

  

 than on pg 39:

 Once cruise power has been set, leaning to best economy should be standard  procedure as damage to the engine will not occur from leaning at cruise power  settings.

  

  

 --

partner14

Joined: 12 Jan 2008
Posts: 540
Location: Granbury Texas

Posted: Mon Aug 11, 2014 7:57 pm Post subject: Lean of Peak and other heresies

How about 9:5 compression?  That's what I have, and I fly LOP everywhere.  Lot's of hp, 3 blade prop... cruise at 1/2 throttle (at 10,500', instead of WOT providing 21.3 inches, I'm around 18.5") and between 2,000 and 2,100 rpm. I'm sure Kelley will tell us what % power that setting is.  Before some of you say "he can't get 21.3" at 10,500, I only get 20.3".... you can if you have a 4" forward facing servo with cold air induction and an F1 Rocket scoop.

With these settings we cruise fast enough (156kts), have a low fuel burn, and the engine temps and my wallet are  very happy.

Don Mc



        From: Les Kearney <kearney(at)shaw.ca>

 To: "rv10-list(at)matronics.com" <rv10-list(at)matronics.com> 

 Sent: Monday, August 11, 2014 10:21 PM

 Subject: Re: Lean of Peak and other heresies

   

 

Hmmm

Has anyone run LOP with 9:1 compression cylinders?

For the IO540, is there a power setting analogous to the Brand C 65% power setting that eliminates the red box risk?

Cheers

Les



Sent from my iPhone



On Aug 11, 2014, at 8:53 PM, Kelly McMullen <apilot2(at)gmail.com (apilot2(at)gmail.com)> wrote:

[quote]Pascal has it right. Lycoming says you are too inattentive, too dumb and basically incapable of operating lean of peak because a. their engineers have never tried it

 

b. their engineers are too stupid to understand it



c. their lawyers perceive a little itty bitty risk that must be avoided



d. they wouldn't want to change from what they recommended 50 yrs ago.

 

I've operated my 200 hp Lycoming IO-360-A1A LOP for the past 12 yrs or 700 hours without a problem.  Prior to that it had some valve sticking that probably caused overload on the cam lobes that resulted in spalled cam lobes and lifters. It is stock 8.7:1 compression requiring 100 octane minimum...closer to detonation margin than an stock IO-540 260 hp at 8.5:1 compression.

 

The main thing is to understand that you have one reference point for ROP (when the first cylinder peaks) and LOP (when the LAST cylinder peaks). I normally run full throttle and 10-20 LOP anywhere above 6000 ft (~24" MAP). Fuel consumption will be about 0.5 gph per cylinder less than same power ROP.

 

75% for IO-540=195hp = ~13gph LOP.



65%=169hp=~11.3 gph



for normally aspirated engines between 8.5 and 8.7 to 1 compression when LOP power=FF*15  (14.9 if you want that much precision)



 



On Mon, Aug 11, 2014 at 7:18 PM, Les Kearney <kearney(at)shaw.ca (kearney(at)shaw.ca)> wrote:

[quote] Hi Pascal

Here is a link to the monograph I hot from Lycoming at KOSH. 

http://www.shamrockairservices.com/images/LEANING%20TECHNIQUES.pdf

 



Cheers

Les



Sent from my iPhone



On Aug 11, 2014, at 7:43 PM, "Pascal" <rv10flyer(at)live.com (rv10flyer(at)live.com)> wrote:

 

[quote]    Plainly put the lycoming rep was uneducated on the Lycoming stance:

 http://www.avweb.com/news/maint/182849-1.html?redirected=1

 Lie #7:

 Aggressive leaning results in burned valves and detonation.

  

 Fear of the red knob is one of the most pernicious areas of misinformation  among general aviation pilots. Most pilots operate way too rich most of the  time, and do so because of the mistaken belief that leaning will harm their  engine. The result is usually trouble: fouled spark plugs, accelerated exhaust  valve guide wear, and stuck exhaust valves.

  

 Lycoming engine Lycoming has long authorized leaning to peak EGT at any  cruise setting up to 75% power. TCM authorizes leaning to peak EGT up to 65%,  and its latest recommendations even endorse lean-of-peak operation for many  big-bore engines, provided the engines will run smoothly when operated that  lean.

  

 Contrary to popular belief, aggressive leaning doesn't cause burned valves.  Most burned valves are the result of excessive valve guide wear or valve stem  contamination.

  

 Aggressive leaning doesn't cause detonation, either. Most of our engines  are incapable of detonation at cruise power settings, provided that we don't  exceed CHT red-line or try to burn contaminated fuel. Furthermore, recent tests  on Lycoming engines by ASTM revealed this fascinating result: detonation is most  likely to occur at a mixture setting 11% richer than stoichiometric (i.e.,  substantially richer than peak EGT).

  

 Lean as aggressively as the book allows. For Lycomings, that means peak EGT  at all cruise power settings to 75%. For Continentals, lean to peak EGT up to  65%, 50Â°F rich of peak at 75%. For turbocharged engines, also limit TIT to  1600Â°F.

  

 Lean during all ground operations except for engine start. It is  particularly important to lean for taxi and runup. Since EGT is usually  off-scale at idle power, the best method is to lean for peak RPM at idle. 

  

 Read through Lycomingâ€™s Key Operations- found on the lycoming site. Plenty  about leaning at 75% and lower and even a chart that says they do not recommend  LOP, but on the same page has: 

 pg38

 6. Leaning to best economy mixture.

 a. Set manifold pressure and RPM for the desired cruise power setting per  the aircraft POH/AFM.

 b. Lean slowly in small steps, while monitoring instrumentation, to peak  TIT or maximum allowable TIT, whichever occurs first

 

<image[3].png>

  

 than on pg 39:

 Once cruise power has been set, leaning to best economy should be standard  procedure as damage to the engine will not occur from leaning at cruise power  settings.

  

  

 --

_________________
Don A. McDonald
40636

kearney

Joined: 20 Sep 2008
Posts: 563

Posted: Mon Aug 11, 2014 8:06 pm Post subject: Lean of Peak and other heresies

Hi Kelly

I am not too fussed about 100ll. As well, I plan to fly over the rocks to the west. 

Cheers

Les



Sent from my iPhone



On Aug 11, 2014, at 9:47 PM, Kelly McMullen <apilot2(at)gmail.com (apilot2(at)gmail.com)> wrote:

[quote]Les,



Just curious why you would want 9:1 compression when the availability of true 100 octane fuel into the future is questionable?



The gain in horsepower might help a little on really short or high elevation airports, but it isn't going to do much for cruise speed.

 

I don't know anyone that thinks the acceleration and climb of the stock 260 is inadequate for most any normal operation.



The physics is the same. 8.7:1 has almost zero red box and 8.5 to 1 even less. Higher compression just means the red box is bigger and needs more attention, just like a turbo would.

 

On Mon, Aug 11, 2014 at 8:21 PM, Les Kearney <kearney(at)shaw.ca (kearney(at)shaw.ca)> wrote:

[quote] Hmmm

Has anyone run LOP with 9:1 compression cylinders?

For the IO540, is there a power setting analogous to the Brand C 65% power setting that eliminates the red box risk?

 



Cheers

Les



Sent from my iPhone

On Aug 11, 2014, at 8:53 PM, Kelly McMullen <apilot2(at)gmail.com (apilot2(at)gmail.com)> wrote:

 



[quote]Pascal has it right. Lycoming says you are too inattentive, too dumb and basically incapable of operating lean of peak because a. their engineers have never tried it

  

b. their engineers are too stupid to understand it



c. their lawyers perceive a little itty bitty risk that must be avoided



d. they wouldn't want to change from what they recommended 50 yrs ago.

  

I've operated my 200 hp Lycoming IO-360-A1A LOP for the past 12 yrs or 700 hours without a problem.  Prior to that it had some valve sticking that probably caused overload on the cam lobes that resulted in spalled cam lobes and lifters. It is stock 8.7:1 compression requiring 100 octane minimum...closer to detonation margin than an stock IO-540 260 hp at 8.5:1 compression.

  

The main thing is to understand that you have one reference point for ROP (when the first cylinder peaks) and LOP (when the LAST cylinder peaks). I normally run full throttle and 10-20 LOP anywhere above 6000 ft (~24" MAP). Fuel consumption will be about 0.5 gph per cylinder less than same power ROP.

  

75% for IO-540=195hp = ~13gph LOP.



65%=169hp=~11.3 gph



for normally aspirated engines between 8.5 and 8.7 to 1 compression when LOP power=FF*15  (14.9 if you want that much precision)

 

 



On Mon, Aug 11, 2014 at 7:18 PM, Les Kearney <kearney(at)shaw.ca (kearney(at)shaw.ca)> wrote:

 [quote] Hi Pascal

Here is a link to the monograph I hot from Lycoming at KOSH. 

http://www.shamrockairservices.com/images/LEANING%20TECHNIQUES.pdf

  



Cheers

Les



Sent from my iPhone



On Aug 11, 2014, at 7:43 PM, "Pascal" <rv10flyer(at)live.com (rv10flyer(at)live.com)> wrote:

  

[quote]    Plainly put the lycoming rep was uneducated on the Lycoming stance:

 http://www.avweb.com/news/maint/182849-1.html?redirected=1

 Lie #7:

 Aggressive leaning results in burned valves and detonation.

  

 Fear of the red knob is one of the most pernicious areas of misinformation  among general aviation pilots. Most pilots operate way too rich most of the  time, and do so because of the mistaken belief that leaning will harm their  engine. The result is usually trouble: fouled spark plugs, accelerated exhaust  valve guide wear, and stuck exhaust valves.

  

 Lycoming engine Lycoming has long authorized leaning to peak EGT at any  cruise setting up to 75% power. TCM authorizes leaning to peak EGT up to 65%,  and its latest recommendations even endorse lean-of-peak operation for many  big-bore engines, provided the engines will run smoothly when operated that  lean.

  

 Contrary to popular belief, aggressive leaning doesn't cause burned valves.  Most burned valves are the result of excessive valve guide wear or valve stem  contamination.

  

 Aggressive leaning doesn't cause detonation, either. Most of our engines  are incapable of detonation at cruise power settings, provided that we don't  exceed CHT red-line or try to burn contaminated fuel. Furthermore, recent tests  on Lycoming engines by ASTM revealed this fascinating result: detonation is most  likely to occur at a mixture setting 11% richer than stoichiometric (i.e.,  substantially richer than peak EGT).

  

 Lean as aggressively as the book allows. For Lycomings, that means peak EGT  at all cruise power settings to 75%. For Continentals, lean to peak EGT up to  65%, 50Â°F rich of peak at 75%. For turbocharged engines, also limit TIT to  1600Â°F.

  

 Lean during all ground operations except for engine start. It is  particularly important to lean for taxi and runup. Since EGT is usually  off-scale at idle power, the best method is to lean for peak RPM at idle. 

  

 Read through Lycomingâ€™s Key Operations- found on the lycoming site. Plenty  about leaning at 75% and lower and even a chart that says they do not recommend  LOP, but on the same page has: 

 pg38

 6. Leaning to best economy mixture.

 a. Set manifold pressure and RPM for the desired cruise power setting per  the aircraft POH/AFM.

 b. Lean slowly in small steps, while monitoring instrumentation, to peak  TIT or maximum allowable TIT, whichever occurs first

 

<image[3].png>

  

 than on pg 39:

 Once cruise power has been set, leaning to best economy should be standard  procedure as damage to the engine will not occur from leaning at cruise power  settings.

  

  

 --

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Mon Aug 11, 2014 8:07 pm Post subject: Lean of Peak and other heresies

The only way to determine power LOP is by the fuel flow calculation     I provided earlier.Â  While higher compression does provide somewhat     better efficiency, it is offset by lower detonation margins. I don't     know whether WOT with stock compression would be less or equally     efficient than partial throttle with higher compression. I do know     that partial throttle does disrupt the airflow into the manifold.     Whether that offsets some of the efficiency gain would probably have     to be determined on a dyno or other instrumented setup.

     I just prefer the keep it simple way of doing things, so that if     something fails, I can get replacement stock parts, and I don't have     to worry if I find myself somewhere that only 91 octane mogas is     available.

     All choices that we get to make as amateur builders. Only those that     make sense for our individual needs are the right ones.

     Kelly

     On 8/11/2014 8:56 PM, Don McDonald       wrote:

     

     [quote]                How about 9:5 compression?Â  That's what I have, and I             fly LOP everywhere.Â  Lot's of hp, 3 blade prop... cruise at             1/2 throttle (at 10,500', instead of WOT providing 21.3             inches, I'm around 18.5") and between 2,000 and 2,100 rpm.             I'm sure Kelley will tell us what % power that setting is.Â              Before some of you say "he can't get 21.3" at 10,500, I only             get 20.3".... you can if you have a 4" forward facing servo             with cold air induction and an F1 Rocket scoop.

         With             these settings we cruise fast enough (156kts), have a low             fuel burn, and the engine temps and my wallet are very             happy.

         Don             Mc

           

         

         

                                                  From: Les                 Kearney <kearney(at)shaw.ca> (kearney(at)shaw.ca)

                 To:                 "rv10-list(at)matronics.com" (rv10-list(at)matronics.com)                 <rv10-list(at)matronics.com> (rv10-list(at)matronics.com) 

                 Sent:                 Monday, August 11, 2014 10:21 PM

                 Subject:                 Re: Lean of Peak and other heresies

                

             

                                                   Hmmm

                   

                   

                   Has anyone run LOP with 9:1 compression                     cylinders?

                   

                   

                   For the IO540, is there a power setting analogous                     to the Brand C 65% power setting that eliminates the                     red box risk?

                   

                   

                   Cheers

                   

                   

                   Les

                   

                     Sent from my iPhone

                   

                     On Aug 11, 2014, at 8:53 PM, Kelly McMullen <apilot2(at)gmail.com (apilot2(at)gmail.com)>                     wrote:

                     

                   

                   [quote]                                                                                                                                                                                                                                                                                                            Pascal has it right. Lycoming                                         says you are too inattentive,                                         too dumb and basically incapable                                         of operating lean of peak                                         because a. their engineers have                                         never tried it

                                       

                                       b. their engineers are too stupid                                       to understand it

                                     

                                     c. their lawyers perceive a little                                     itty bitty risk that must be avoided

                                   

                                   d. they wouldn't want to change from                                   what they recommended 50 yrs ago.

                                 

                                 I've operated my 200 hp Lycoming                                 IO-360-A1A LOP for the past 12 yrs or                                 700 hours without a problem.Â  Prior to                                 that it had some valve sticking that                                 probably caused overload on the cam                                 lobes that resulted in spalled cam lobes                                 and lifters. It is stock 8.7:1                                 compression requiring 100 octane                                 minimum...closer to detonation margin                                 than an stock IO-540 260 hp at 8.5:1                                 compression.

                               

                               The main thing is to understand that you                               have one reference point for ROP (when the                               first cylinder peaks) and LOP (when the                               LAST cylinder peaks). I normally run full                               throttle and 10-20 LOP anywhere above 6000                               ft (~24" MAP). Fuel consumption will be                               about 0.5 gph per cylinder less than same                               power ROP.

                             

                             75% for IO-540=195hp = ~13gph LOP.

                           

                           65%=169hp=~11.3 gph

                         

                         for normally aspirated engines between 8.5 and                         8.7 to 1 compression when LOP power=FF*15Â  (14.9                         if you want that much precision)

                       

                                                

                         

                         On Mon,                           Aug 11, 2014 at 7:18 PM, Les Kearney <kearney(at)shaw.ca (kearney(at)shaw.ca)>                           wrote:

                           [quote]                                                            Hi Pascal

                               

                               

                               Here is a link to the monograph I hot                                 from Lycoming at KOSH.Â 

                               

                               

                               http://www.shamrockairservices.com/images/LEANING%20TECHNIQUES.pdf

                               

                               

                               Cheers

                               

                               

                               Les

                                 

                                 Sent from my iPhone

                                                                

                                   On Aug 11, 2014, at 7:43 PM, "Pascal"                                   <rv10flyer(at)live.com (rv10flyer(at)live.com)>                                   wrote:

                                   

                                 

                               

                               [quote]                                                                                                                                                                                         Plainly put the lycoming                                           rep was uneducated on the                                           Lycoming stance:

                                         http://www.avweb.com/news/maint/182849-1.html?redirected=1

                                         Lie #7:

                                         Aggressive leaning results                                           in burned valves and                                           detonation.

                                         Â 

                                         Fear of the red knob is one                                           of the most pernicious areas                                           of misinformation among                                           general aviation pilots. Most                                           pilots operate way too rich                                           most of the time, and do so                                           because of the mistaken belief                                           that leaning will harm their                                           engine. The result is usually                                           trouble: fouled spark plugs,                                           accelerated exhaust valve                                           guide wear, and stuck exhaust                                           valves.

                                         Â 

                                         Lycoming engine Lycoming                                           has long authorized leaning to                                           peak EGT at any cruise setting                                           up to 75% power. TCM                                           authorizes leaning to peak EGT                                           up to 65%, and its latest                                           recommendations even endorse                                           lean-of-peak operation for                                           many big-bore engines,                                           provided the engines will run                                           smoothly when operated that                                           lean.

                                         Â 

                                         Contrary to popular belief,                                           aggressive leaning doesn't                                           cause burned valves. Most                                           burned valves are the result                                           of excessive valve guide wear                                           or valve stem contamination.

                                         Â 

                                         Aggressive leaning doesn't                                           cause detonation, either. Most                                           of our engines are incapable                                           of detonation at cruise power                                           settings, provided that we                                           don't exceed CHT red-line or                                           try to burn contaminated fuel.                                           Furthermore, recent tests on                                           Lycoming engines by ASTM                                           revealed this fascinating                                           result: detonation is most                                           likely to occur at a mixture                                           setting 11% richer than                                           stoichiometric (i.e.,                                           substantially richer than peak                                           EGT).

                                         Â 

                                         Lean as aggressively as the                                           book allows. For Lycomings,                                           that means peak EGT at all                                           cruise power settings to 75%.                                           For Continentals, lean to peak                                           EGT up to 65%, 50Â°F rich of                                           peak at 75%. For turbocharged                                           engines, also limit TIT to                                           1600Â°F.

                                         Â 

                                         Lean during all ground                                           operations except for engine                                           start. It is particularly                                           important to lean for taxi and                                           runup. Since EGT is usually                                           off-scale at idle power, the                                           best method is to lean for                                           peak RPM at idle. 

                                         Â 

                                         Read through Lycomingâ€™s Key                                           Operations- found on the                                           lycoming site. Plenty about                                           leaning at 75% and lower and                                           even a chart that says they do                                           not recommend LOP, but on the                                           same page has: 

                                         pg38

                                         6. Leaning to best economy                                           mixture.

                                         a. Set manifold pressure                                           and RPM for the desired cruise                                           power setting per the aircraft                                           POH/AFM.

                                         b. Lean slowly in small                                           steps, while monitoring                                           instrumentation, to peak TIT                                           or maximum allowable TIT,                                           whichever occurs first

                                       

                                       <image[3].png>

                                                                                Â 

                                         than on pg 39:

                                         Once cruise power has been                                           set, leaning to best economy                                           should be standard procedure                                           as damage to the engine will                                           not occur from leaning at                                           cruise power settings.

                                         Â 

                                         Â 

                                         --

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Mon Aug 11, 2014 8:18 pm Post subject: Lean of Peak and other heresies

Hi Les,

Like I said, individual choices, individual opinions. Compression needs 

are probably related to which primer you used......................

IIRC the -10 will climb over any rock in North America with a stock 

engine. I know the service ceiling is higher than my 200 hp Mooney that 

will do 18,800 for service ceiling. IIRC there aren't too many rocks in 

Canada besides Mt. Logan that are in the upper teens.

Of course most of us ignore the advice that mods take time, money, more 

time and more money.



On 8/11/2014 9:06 PM, Les Kearney wrote:

 	  Quote: 	
		   Hi Kelly



 I am not too fussed about 100ll. As well, I plan to fly over the rocks 

 to the west.



 Cheers



 Les



 Sent from my iPhone

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

Jim Berry

Joined: 10 Jan 2006
Posts: 237
Location: Denver

Posted: Mon Aug 11, 2014 9:03 pm Post subject: Re: Lean of Peak and other heresies

 	  kearney wrote: 	
		  Hmmm

Has anyone run LOP with 9:1 compression cylinders?

For the IO540, is there a power setting analogous to the Brand C 65% power setting that eliminates the red box risk?

Cheers

Les



 -- 	




Since I primed everything, I figured I needed 9:1 pistons to get off the ground. My Barrett IO-540 also has roller cam, Bendix 1200 mags, and AFP injection with restrictors matched to 0.1 gal thanks to Don Rivera. My home field elevation is 5800 ft. I routinely run WOT, 23-2400 rpm and LOP (at) 10-10.5 gph. I do the big pull in less than 5 seconds, so don't worry much about the red box. After 4 years and approx. 400 hours, boroscope, plugs, oil analysis and compression all remain great.



Jim Berry

Mike Whisky

Joined: 05 Jun 2006
Posts: 336
Location: Switzerland

Posted: Tue Aug 12, 2014 4:31 am Post subject: Re: Lean of Peak and other heresies

I run my TMX-IO-540 always LOP. Usually at 8-9.5k WOT it generates 160 TAS using 38-40l/h which is about 10-10.5 USGAL .



You should take the advanced pilot seminar online course this will make you understand the physics behind engine management. I after break in I spent all my flights on injector balancing and I am now at a 2l difference which works for now. Clearly electronic engine monitoring and balanced fuel flow injection is a prerequisite for LOP ops. Given that I pay about 11.7$ per USgal LOP makes a lot of sense from an economical view as well. 



Mike

_________________
RV-10 builder (flying)
#511

Display posts from previous:

	Matronics Email Lists Forum Index -> RV10-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum