LOP: A few questions.

[Parker_Woodruff]

Quote: JimR

Jim

[KSMooniac]

I concur with all of the recent advice above.  Jim, yes, you can pull to 8.5 GPH at any altitude and any RPM of your choosing, and then keep an eye on CHTs if it is hot outside.  There is a secondary effect on efficiency with the prop efficiency factor at various RPMs, so you might run some tests while you're in 8.5 GPH cruise mode some time in smooth air.  Try several different RPM settings while keeping 8.5 GPH constant (you'll have to move the red knob each time the blue knob moves) and wait a few minutes for speed to stabilize.  You might be able to notice a difference in speed.  After finding the best RPM setting at 8.5 GPH, I would find peak again and see where 8.5 GPH leaves you on the LOP side, just out of curiosity.

[GeorgePerry]

Quote: Bnicolette

Alright guys.....I'm a bit thick so help me out with this please.  I am playing around with LOP ops.  I have a JPI830 and am trying to use it to come up with LOP values.  According to the JPI's video they want you to continue leaning until you first see "leanest" and then "richest".  However, I am a bit confused by this.  During my leaning and after seeing the "leanest" message I start watching my EGT value that the JPI display has at the bottom.  If I am shooting for 30 LOP I stop when I see -30 or close to it.  However, that usually happens before I see "richest" come up on the JPI?   What am I doing right or wrong?  As I said, I am a bit thick and a leaning rookie, so be gentle.  Here is a video I did of the process today.  Sorry about the camera shaking all around and it also took me a while to focus on certain things.  So sorry for that.

http://www.youtube.com/watch?v=XZ8sqOAGPRA

[jetdriven]

George, the IO-360 is unusualy in the idea that most do not need GAMI injectors to run well LOP.  The engine has tuned induction. FWIW ours has a .2 GPH GAMI spread. 

[jetdriven]

Quote: KSMooniac

I concur with all of the recent advice above.  Jim, yes, you can pull to 8.5 GPH at any altitude and any RPM of your choosing, and then keep an eye on CHTs if it is hot outside.  There is a secondary effect on efficiency with the prop efficiency factor at various RPMs, so you might run some tests while you're in 8.5 GPH cruise mode some time in smooth air.  Try several different RPM settings while keeping 8.5 GPH constant (you'll have to move the red knob each time the blue knob moves) and wait a few minutes for speed to stabilize.  You might be able to notice a difference in speed.  After finding the best RPM setting at 8.5 GPH, I would find peak again and see where 8.5 GPH leaves you on the LOP side, just out of curiosity.

[jetdriven]

Quote: JimR

Nice Tip!

[GeorgePerry]

Quote: jetdriven

George, the IO-360 is unusualy in the idea that most do not need GAMI injectors to run well LOP.  The engine has tuned induction. FWIW ours has a .2 GPH GAMI spread. 

[bnicolette]

I think I did it correctly. 

[Immelman]

[Deleted.. his engine is broken in by now]

[John Pleisse]

No biggie......

[bnicolette]

Quote: N4352H

No biggie......

[Cruiser]

The most common cause of exhaust leak. Notice the width of the valve face in the upper right hand picture. To the left it is narrow and to the right it is wide. The valve is not centered to the guide so that the grinding stone used to grind the valve face ground more on the left than on the right. More stone pressure was on the left. When you install the valve the same thing happens--more seat pressure occurs on the right hand side than on the left. Leakage occurs on the left hand side where the valve seating pressure is less. This is an example of how poor machining is the most common reason exhaust valves leak --not leaning or pilot technique.

It is unfortunate to have this example of poor machining show up in a LOP discussion as it has absolutely nothing to do with LOP or operator technique. Hopefully most reputable shops have this figured out now and this type of shoddy workmanship is a thing of the past.

[John Pleisse]

Quote: Cruiser

The most common cause of exhaust leak. Notice the width of the valve face in the upper right hand picture. To the left it is narrow and to the right it is wide. The valve is not centered to the guide so that the grinding stone used to grind the valve face ground more on the left than on the right. More stone pressure was on the left. When you install the valve the same thing happens--more seat pressure occurs on the right hand side than on the left. Leakage occurs on the left hand side where the valve seating pressure is less. This is an example of how poor machining is the most common reason exhaust valves leak --not leaning or pilot technique.

It is unfortunate to have this example of poor machining show up in a LOP discussion as it has absolutely nothing to do with LOP or operator technique. Hopefully most reputable shops have this figured out now and this type of shoddy workmanship is a thing of the past.

[bnicolette]

Quote: N4352H

[John Pleisse]

Quote: Bnicolette

[jetdriven]

Quote: N4352H

No biggie......

[jetdriven]

Quote: Cruiser

The most common cause of exhaust leak. Notice the width of the valve face in the upper right hand picture. To the left it is narrow and to the right it is wide. The valve is not centered to the guide so that the grinding stone used to grind the valve face ground more on the left than on the right. More stone pressure was on the left. When you install the valve the same thing happens--more seat pressure occurs on the right hand side than on the left. Leakage occurs on the left hand side where the valve seating pressure is less. This is an example of how poor machining is the most common reason exhaust valves leak --not leaning or pilot technique.

It is unfortunate to have this example of poor machining show up in a LOP discussion as it has absolutely nothing to do with LOP or operator technique. Hopefully most reputable shops have this figured out now and this type of shoddy workmanship is a thing of the past.

[PTK]

If the earth is indeed round, as some rumors still persist to circulate, then why are our charts and runways flat?

The earth is flat folks! No more earth is round rumors, please! People were hanged for spreading such blasphemy!

[mooneygirl]

Oh my goodness boys....let's get out there and fly our Mooneys!  ROP or LOP. 

[bnicolette]

Quote: mooneygirl

Oh my goodness boys....let's get out there and fly our Mooneys!  ROP or LOP. 

[danb35]

Quote: jetdriven

8.5 GPH is going to be ROP at a density altitude above around 8K.  Careful with that.  Lean to 15 LOP, and use the fuel flow displayed to calculate HP.  Want more or less? change RPM.

[Parker_Woodruff]

Tomorrow I'm hoping for nonstop from Dallas to Richmond, VA at FL190-FL210 and landing with about 1.5 hours on board. Sure couldn't do that ROP.

Whether or not the scattered T-storms let me keep my routing and altitude preferences is another question...

[John Pleisse]

Quote: jetdriven

(picture of burned valve)

 

Perhas our dear friend John  (Hugs Byron.....)

can explain the fact that radial airliners operated LOP for about 40 years, and had TBOs of 3600 hours. In fact it won the War for us, as the ROP technique couldnt make a roundtrip to Germany.

WW2...large diplacement, low compression, radial engines...may super charged...using more oil than gas....we won the war.

Or that the Continental TSIO-520BE engine in the Piper Malibu was designed to run LOP and did so.

Continental........... (and what was the HP rating on that engine? Service history)?

Or the A-36 Bonanza with the IO-550-BB and LOP charts in the book.

Continental

How the Cirrus SR22 is authorized to cruise LOP and even has an LOP FF limit. NA or Turbo, and warrantied.

Continental

Or how 50 LOP is somehow hotter than 50 ROP.  Think about that one.

Well, it is...air will burn hotter than fuel.

Or how an IO-360 like ours runs a 330 CHT LOP while 380 ROP.

Yes..and you have also made mesmorizing claims of 280 LOP. Less ferver?

How the old "lean to rough, then enrich till smooth" technique is actually LOP on many engines.

Which ones?

The total lack of any credible literature correlating burned up valves with LOP opearation.

And nothing is proven to the conbtrary with small Lyc's....other than test data on Continentals

The fact Lycoming authorized operating AT PEAK at any power setting 75% or less. Go ahead. Its blessed.

Post it.... remember...we have 360 series engines.

The fact Lycoming actually says LOP is OK now (OSH 2011), but pilots arent adept enough at monitoring their engines to do it practically.

Yes...to you and a handful of others. I imagine you were quite assertive at OSH. You were quick to dissmentinate on the web. The margins are more narrow on the Lyc's, so as a manufacturer their position is reasonable.

But there is always "science by consensus" and "my mechanic told me in 1980 that too lean burns valves"

He was right...

At one time 100% of people thought the earth was flat.  Some still do.

I was hoping for something more profound...like............ the "metallurgy " of the cylinder..........

 

I buy it... I believe it...it's there. But $1.00 avgas would make this discussion irrelavent. Cylinders are worth more than avgas, because safety, reliablity, and liability never show up on the bottomline. The service history of the IO-360 series engine is exceptional and not by accident.

 

[PTK]

 

...The total lack of any credible literature correlating burned up valves with LOP opearation.

At one time 100% of people thought the earth was flat.  Some still do....

 

 

[Parker_Woodruff]

Quote: allsmiles

I'll bet you that if there is some long term study out there, say the past 30-40 years or so, that correlates "mixture" to exhaust valve heat loading, it will show exactly that! Undissipated exhaust heat damages valves and guides.