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LOP for a dummy?

74657

By 74657
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74657 Proficient

74657

Posted
Posted

Does anyone have a good article for me to reference on running LOP?  I'm ready to give it a try.  My plane is equipped with an EDM-830 and I have read enough to understand the basics but am foggy on a few issues:


1.  When leaning I go X degrees (40?) leaner than the LAST cylinder to peak?  How many degrees LOP is optimal/best? 


2.  Transitioning from Cruise to Descent - how do you guys go about this?


The Youtube videos I searched for the operation of the 830 isn't crystal clear.  Perhaps I am over thinking this, I just don't want to mess up a perfectly running freshly overhauled engine.


My current operation of ROP involves keeping the EGT's under/at 1400 and the CHT's under 400 on my EDM (My engine has tanis heaters in the cylinder head bungs so I have to use spark plug probes which read ~ 40 degrees hotter than "normal" sensors). 


On my recent flights to and back from FL I ran ~ 20-21" 8K/9K ft, 2350 RPM, 15.3 gph/ 175-180 kts TAS running ROP.  I still had more power left in the engine but wanted to keep the fuel flows at/under 15 gph.  I also read an article (Mike Busch maybe) that explained the benefits of running lower rpm's in cruise, thats my reason for 2350.  The plane is actually quieter at 2500 though.


Thanks guys.


 


Brandon


 

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Cruiser Grand Master

Cruiser

Posted
Posted

Quote: 74657

Does anyone have a good article for me to reference on running LOP?  I'm ready to give it a try.  My plane is equipped with an EDM-830 and I have read enough to understand the basics but am foggy on a few issues:

1.  When leaning I go X degrees (40?) leaner than the LAST cylinder to peak?  How many degrees LOP is optimal/best? 

This depends on your altitude and power settings. The BSFC curve shows LOP operations are optimal at around 20°-40°F LOP. Any leaner and the efficiency of LOP operations start to decline. HOWEVER, the excess ICP envolope peaks around 7000'. Below that altitude you must go further LOP to stay away from high cylinder pressures. Down low you may be as much as 80°F LOP or more. Search on "red box" to see a graphic of this. For turbo operations, keep your power below 65%.

2.  Transitioning from Cruise to Descent - how do you guys go about this?

Nothing, leave the mixture alone. In a normal descent you do not have to richen the fuel. Just remember to reset it in your landing check list.

The Youtube videos I searched for the operation of the 830 isn't crystal clear.  Perhaps I am over thinking this, I just don't want to mess up a perfectly running freshly overhauled engine.

My current operation of ROP involves keeping the EGT's under/at 1400 and the CHT's under 400 on my EDM (My engine has tanis heaters in the cylinder head bungs so I have to use spark plug probes which read ~ 40 degrees hotter than "normal" sensors). 

On my recent flights to and back from FL I ran ~ 20-21" 8K/9K ft, 2350 RPM, 15.3 gph/ 175-180 kts TAS running ROP.  I still had more power left in the engine but wanted to keep the fuel flows at/under 15 gph.  I also read an article (Mike Busch maybe) that explained the benefits of running lower rpm's in cruise, thats my reason for 2350.  The plane is actually quieter at 2500 though.

Thanks guys.

 

Brandon

 

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carusoam Grand Master

carusoam

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Posted

Somebody recently posted the red box graph.  APS is the source of the graph. Search for the graph and the discussion that follows it.


The io550 in the O1 has POH numbers that are 50 deg LOP.  As per the above discussion,  you can avoid the red box and use peak in place of LOP.


You will probably see numbers closer to 12 gph at the same conditions you indicate above.


Best regards,


 


-a-

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testwest Experienced

testwest

Posted
Posted

There is a pretty good summary of Deakin's work on the Vans Air Force web site:


Understanding LOP Operations - A Summary of John Deakin's Knowledge


http://www.vansairforce.com/community/showthread.php?t=75132


But you may want to read through all of the articles in depth as CLRB suggested too.


You're flying an Ovation, right?

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Shadrach Grand Master

Shadrach

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Quote: Cruiser

 I have yet to encounter conditions that require more than about 45dfLOP with my IO360A1A (25BTDC) even at 1000ftMSL the CHTs are <350df.

Oddly, yesterday, I was at 3500ftmsl (DA was probably closer to 2700). CHTs were cooler at 35LOP than full rich. Go figure...

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jetdriven Grand Master

jetdriven

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Your goal is ~15-50 LOP on the last cylinder to peak, a smooth running engine, and a CHT under 380, preferrably in the 360 range.   CHT is your long term trend as to whether the mixture is a good setting.  Every engine has a thredshold where it goes from smooth to uneven, then rough.  On our IO-360-A3B6D, its around 100 LOP. 

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jetdriven Grand Master

jetdriven

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To learn more than you can digest in a week search "LOP" here, at BeechTalk, and over at VAF forums.  After you read all the threads, you will be qualified to teach a 400 level college class on the material.   FWIW Walter Atkinson and The old Pelican himself, John Deakin, post on Beechtalk.  The members there  are a lot like us but they pay double for fuel to get somewhere and don't call each other Nazi's or liberals.  Check it out. 

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carusoam Grand Master

carusoam

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Posted

Eb,


Look up GAMI lean test.  This is a simple measurement to determine how similar you injectors are flowing.


With the io-550 and well matched injectors (tight GAMI spread) you might lean smoothly until the engine dies.  That's how mine works.


My o-360 would shake like crazy and would refuse lop ops in comparison.


Best regards,


-a-

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KSMooniac Grand Master

KSMooniac

Posted
Posted

There is a ton of material on the AOPA Forum too.  Walter A used to be an active poster there, but I guess he has moved on.  I first tuned in almost 5 years ago and I know there were a lot of discussions prior to then, and certainly after I joined.


If you want the best, most comprehensive and efficient learning experience, then consider taking the Advanced Pilot Seminars course.

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