Contentious ROP

[Txbyker]

I don't want to create a controversy but I have a question from one of the ROP-ers that has not ventured into the LOP-dom.

I have gotten many conflicting signals as to the best place to lean at ROP.

- Mooney purchase checkout by a reputable ex-factory test pilot - "run it 50 ROP"

- POH - 25 ROP for economy, 100 ROP for power.

- Bob Kromer - "I think you really have three choices of mixture settings with a normally aspirated engine. They are 1) 50 degrees rich of peak EGT (Exhaust Gas Temperature), 2) peak EGT, 3) 50 degrees lean of peak EGT. My choice? 50 degrees rich of peak EGT. All the time."

- John Deakin - #65 Pelican Perch - " If you want the most power you can get at the higher altitudes, then you must operate ROP, and 50 ROP is a pretty good place to be for that. As you climb higher and higher, you can experiment with the mixture control, and find out where peak EGT occurs, then just ballpark about 50 ROP."

- Mooneyspace veterans - run lower than 100 ROP.

Am getting a bit confused.  I have always run 50-100 ROP and now after reading all of the threads on LOP and other ROP questions I feel like I am messing up the engine.  

What say you?

[Parker_Woodruff]

Assuming you are wide open throttle, the amount you need to be LOP will vary with altitude. (this is because you have a NA IO-360)

At 6000', You'll have to be somewhere in the 40-50 dF LOP range, while at 12,000', just get the richest cylinder to about 10 dF LOP.  With such low power settings up at high altitude, all you're leaning past peak for is to keep the cylinders cool.

[jetdriven]

Depending on the exact modus operandii, anywhere from 250 ROP to 150 LOP is appropriate.  At 75% power and below, Lycoming authorizes peak EGT continuous. As of OSH last year they said they no longer object to LOP, just that you are too dumb to recognize a trend before it ruins a cylinder.  No comment was made on the idea that if it is LOP at a 330 CHT, how does that cylidner get hotter?  Leaner is cooler.

Do thr GAMi spread. Do the Hi-low induction leak test. Do a LOP inflight mag check.  Pass all 3, good.  OK, now lean until it changes tone and slows slightly, like going down thr highway and leting off the gas.  Thats around 20 LOP right there.  If it will not run smoothly, or any CHT exceeds 380, get out.  Go comfortably ROP and investigate later.

Of the 3, go with Deakin. You know he is a regular poster on Beechtalk, you can sign up and ask him your questions and he will answer.

  Climb at target.  Below 2K density altitude, prop to 2500, pull the red knob of death to 8.5-10.0.  Done. At low altitude, betweeen 2-4K DA, run a max FF of 10.0 GPH for cruise.  I like 2300-2500 RPM.   Low RPM is quieter and slower.  Lean beyond peak around 50 degrees, and if it above 10.0 GPH, lean to 10.0 GPH (the 75% limit). Cruise between 3 or 4K to 9K (density altitude), run 15-50 LOP, depending on need for speed and CHT.  Slow is the lower FF limit.  380 CHT is the upper FF limit.  I like to run 15 LOP and a 360 CHT.  At 10K or over, you are going to need 2700 RPM and 80 ROP to make max speed.  The M20J runs out of HP long before it runs out of wing.  You need that power up there.

[Immelman]

Have you read Deakin's articles on Avweb about the 'red box'? That really let all this stuff 'click' for me. Here's the relevant piece on cruise flight:

http://www.avweb.com/news/columns/182583-1.html

Sort of like my political preference, I am neither a ROP person or an LOP person. I pick my mixture setting appropriate the amount of engine power being produced (see the 'red box' article), and how fast I want to go vs. how much fuel I want to burn. I will fly 200 ROP, 100 ROP, 50 ROP, peak, lean of peak... it all depends! The basic premise is how far ROP or LOP you need to be (if at all) depends on how much power the engine is producing. If you're in an NA airplane down low, you need to think about this. As you get higher, the power your engine produces drops, and you can eventually put the mixture anywhere you like.

[201er]

I really don't understand where 50ROP comes from. It just seems like people took a guess that if Peak is economy and 100ROP is power, then split the difference and use that. I have not seen a manufacturer recommendation or intelligent reason for 50 ROP below 8k ever.

[Bolter]

Quote: txbyker

I don't want to create a controversy but I have a question from one of the ROP-ers that has not ventured into the LOP-dom.

I have gotten many conflicting signals as to the best place to lean at ROP.

- Mooney purchase checkout by a reputable ex-factory test pilot - "run it 50 ROP"

- POH - 25 ROP for economy, 100 ROP for power.

- Bob Kromer - "I think you really have three choices of mixture settings with a normally aspirated engine. They are 1) 50 degrees rich of peak EGT (Exhaust Gas Temperature), 2) peak EGT, 3) 50 degrees lean of peak EGT. My choice? 50 degrees rich of peak EGT. All the time."

- John Deakin - #65 Pelican Perch - " If you want the most power you can get at the higher altitudes, then you must operate ROP, and 50 ROP is a pretty good place to be for that. As you climb higher and higher, you can experiment with the mixture control, and find out where peak EGT occurs, then just ballpark about 50 ROP."

- Mooneyspace veterans - run lower than 100 ROP.

Am getting a bit confused.  I have always run 50-100 ROP and now after reading all of the threads on LOP and other ROP questions I feel like I am messing up the engine.  

What say you?

[Txbyker]

Quote: tomcullen

Whether you intended to or not, the debate has started.   Good luck to all competitors and may the odds be ever in your favor.

I want to clarify what is intended in the Deakin quote, however.  The reference to higher altitude, I take to mean when "steady state" at a given altitude, as opposed to suggesting leaning this way during the actual climb.   I would not want someone to read this, and ignore high CHT's in a climb because they heard that you don't need richer than 50° ROP.  

I think a critical message in all the ROP-LOP battles is to keep CHT's at a safe level, regardless of your method.  If you do that, you are avoiding a primary risk.  

-dan

 

Yes Dan, I agree.  I read all of Deakins power setting articles on on climb he suggest more leaning toward a continuous sea level EGT for peak fuel flow.  So 50 ROP at any other time than cruise is not what I meant.

Thanks

[PTK]

Quote: Immelman

I will fly 200 ROP, 100 ROP, 50 ROP, leak, leak of peak... it all depends! The basic premise is how far ROP or LOP you need to be (if at all) depends on how much power the engine is producing. If you're in an NA airplane down low, you need to think about this. As you get higher, the power your engine produces drops, and you can eventually put the mixture anywhere you like.

[John Pleisse]

I am going to patent a mixture knob......to throttle, aileron, rudder, stabilizer, EDM 830 innerconnect. Just turn the red knob and watch the plane fly.

In four-banger Lyc's, there's nothing wrong with 50 ROP. A long service history proves this.

[jlunseth]

When I was at the APS seminar they said 125 ROP for a turbo, I don't remember the number for an NA, probably have it written down at home.  Then flew with a long time Mooney instructor, he said 75 ROP.  What I do know, which would be sacrilege to the APS guys, is set the degrees ROP depending on CHT.  I want my CHT's around 380, so that is how I set degrees ROP.  It is typically around 75, sometimes less sometime more depending on OAT's and what exact % power I am running at.  That is for a turbo 360-LB

[Immelman]

Quote: allsmiles

Just when I decided to become a LOP'er you throw this leak and leak of peak into the mix!! What is this curve ball now!!

[jetdriven]

Quote: N4352H

I am going to patent a mixture knob......to throttle, aileron, rudder, stabilizer, EDM 830 innerconnect. Just turn the red knob and watch the plane fly.

In four-banger Lyc's, there's nothing wrong with 50 ROP. A long service history proves this.

[Hank]

I fly my O-360 at ~50 ROP most of the time, with factory single EGT, OAT and no fuel flow. My long-term average is hovering around 9 gph. I've found two methods to determine peak:  watch the for EGT needle to stop moving [flying solo], or wait for my wife to speak up [otherwise]. She just won't go LOP for nothing! [Neither the engine nor my wife.    The engine stumbles, the wife mumbles.]

My question, though, is this:  what is a safe altitude/MP/power level to run at or near peak? Last week at 9000' msl, OAT varied from 60-65ºF, and I had just over 20" MP available. After a fairly slow climb, I pulled back to 20" to angle the throttle body and improve mixing in the carb. Was I high enough to run at peak? Is that safe at any power setting that nets 65% or less? 60%? Or should I just keep it at 50 ROP and not worry about the little fuel savings? And yes, I do try target EGT climbs but don't always remember [forgetting means climbing full rich all the way].

My vintage Owner's Manual does have fairly comprehensive Performance Tables, but they are keyed to altitude every 2500' from sea level to 12,500' so at 9000 I get to interpolate in my head, not forgetting the +/- 10ºF from standard creates -/+ 1% power in the table. And of course, today I left the memory stick at home--that's what happens when you get dressed in the dark.

[KSMooniac]

The power setting whether ROP or LOP should change according to how much power you are producing.  There is no magic power setting like 50 ROP or 50 LOP that is good all the time, at all cruise settings and at all altitudes.  Learn about the Red Box as described by Deakin and the Advanced Pilot Seminars, and then you'll be able to decide for yourself and explain your decision to others.  Setting 50 ROP because Bob Kromer said that 20 years ago is not a good reason to do so.  He knows a ton about flying Mooneys, but his engine management ideas are antiquated to say the least.  (I believe he even has admitted that within the last few years when asked about those articles from way back)

[jetdriven]

Above 5K its 15-50 LOP for me. Prefer 15.  Down low and I mean, below 2K, I have been trying out 11.5 GPH, which is 87% power LOP.   The hottest CHT was still 330. It loved it.

[Hank]

Scott--

I've read many of Deakin's articles. But I have one giant fuel "injector" that mixes fuel with air before dividing it semi-equally between all four cylinders; this makes it difficult to balance the fuel flow. Also, with no fuel flow instrumentation, there is no magic number I can multiply by to find power produced, and if I did have fuel flow it would be a different number than your J.

There is, however, a nice, safe power level where it is acceptable to run at peak. My question was simple:  I can't remember what it is, can someone please remind me? With knowledge of the correct % power, I can look it up in my Performance Tables and make sure I am there, or I can skip it and just stay 50 ROP. Or I can work my way through the articles again, taking a month or two at lunch until I find it again.

[jetdriven]

Hank, anything below 24" of MP, there is no mixture setting that can harm your bulletproof (moreso than the IO-360) engine.   You will be limited to 65% power by air density..  So, around 5k feet or higher, density altitude.  Cocking the throttle plate is a good tactic.  Some Beech guys use a touch of carb heat as well.

[Hank]

Meanwhile, I notice that nobody has attempted to answer Russ's question, besides Scott's anwer above of "it depends." Everyone else's answer of where to run ROP is different amounts of LOP, sidestepping the question.

Russ, I run at 50 ROP but I make less power than you do. My book says the same thing, 25 ROP for Best Economy, 100 ROP for Best Power. Bob Kromer, my instructor and the previous owner all recommend 50 ROP for most purposes.

I descend power-on, walking the throttle out and the mixture in, to maintain cruise settings for MP & EGT. Approaching the pattern I will adjust as necessary to reach flap speed of 125 mph, sometimes pushing prop forward as an airbrake; if I do that, I push the red lever forward, too.

Thanks, Byron. 24" is my new magic power number. Sometimes I use my Perf. Charts, sometimes the MAPA formula of MP + RPM = 47 or less, so 24"/2300. I typically use 23/2300 for 3000' food runs; 24/22 or 24/23 for 5000-ish approaches; and whatever the book says or WOT - a tad for higher and 2500 when possible. It's surprising how far I have to move the throttle lever to make the needle move at 10,000 msl.

[jetdriven]

I thought this covered it.

Climb at target. 

Below 2K density altitude, prop to 2500, pull the red knob of death to 8.5-10.0.  Done.

At low altitude, betweeen 2-4K DA, run a max FF of 10.0 GPH for cruise.  I like 2300-2500 RPM.   Low RPM is quieter and slower.  Lean beyond peak around 50 degrees, and if it above 10.0 GPH, lean to 10.0 GPH (the 75% limit).

Cruise between 3 or 4K to 9K (density altitude), run 15-50 LOP, depending on need for speed and CHT.  Slow is the lower FF limit.  380 CHT is the upper FF limit.  I like to run 15 LOP and a 360 CHT. 

At 10K or over, you are going to need 2700 RPM and 80 ROP to make max speed.  The M20J runs out of HP long before it runs out of wing.  You need that power up there.

 

 

 

[Txbyker]

Thanks everyone!  Just ordered a set of GAMIs.  After reading everything figured I would try the other contentious leaning method.  $700 should get my money back in about 20-30 hours of flying.

[KSMooniac]

Quote: txbyker

Thanks everyone!  Just ordered a set of GAMIs.  After reading everything figured I would try the other contentious leaning method.  $700 should get my money back in about 20-30 hours of flying.

[KSMooniac]

Quote: Hank

Scott--

I've read many of Deakin's articles. But I have one giant fuel "injector" that mixes fuel with air before dividing it semi-equally between all four cylinders; this makes it difficult to balance the fuel flow. Also, with no fuel flow instrumentation, there is no magic number I can multiply by to find power produced, and if I did have fuel flow it would be a different number than your J.

There is, however, a nice, safe power level where it is acceptable to run at peak. My question was simple:  I can't remember what it is, can someone please remind me? With knowledge of the correct % power, I can look it up in my Performance Tables and make sure I am there, or I can skip it and just stay 50 ROP. Or I can work my way through the articles again, taking a month or two at lunch until I find it again.

[M016576]

Quote: txbyker

Thanks everyone!  Just ordered a set of GAMIs.  After reading everything figured I would try the other contentious leaning method.  $700 should get my money back in about 20-30 hours of flying.

[testwest]

Hi Russ

Byron (Jetdriven), Scott S (KSMooniac) and Parker know what they are talking about. There are others on this forum, who don't.

Having said that, if you have been running 50-100 degF ROP with cylinders below "about" 380 degF you probably haven't messed up anything. If there is a lot of flying at 50ROP and 430 degF cylinders, you "may" have caused more wear on the cylinders than would otherwise be possible. Not damage, just wear.

I am pretty sure (but don't know for certain) that diehard LOPers aren't having to top their engines every 600-1000 hours. We have 1100 hours on our old-skool chrome cylinders, and compressions are all above 70 still.

Byron mentioned, "climb at target" in other words the Target EGT method - see the attached pictures from KSMooniac's airplane. This is a Target EGT climb at WOT/2700 from KAAO, up to 8000'. Folks, this is how you do it. Russ, does "Target EGT" have meaning for you?

The other picture is what happens when you leave the mixture full rich. At top of climb at 8000' with Target EGT the fuel flow is 13.9 gph, at full rich the FF is 15.6 gph.

You are much more efficient climbing at WOT/2700/Target at 115 KIAS in an M20J (and using 500 fpm climb when the performance drops to that level, around 6000-7000 feet or so) than you are at Vy and WOT/2700/Full Rich, or the dreaded 25 square. The flights whose data are shown below were flown back to back by KSMooniac, with me in the right seat. The first climb (called Vz, by the way) leveled off 19 miles down path. The second Vy climb leveled off at 12 miles, then Scott cruised at his absolute best 65%LOP capability to the 19 mile point. Fuel used to 19 miles - exactly the same. Average speed to 19 miles (actually, velocity made good), 20 knots faster for the Vz climb.

This is the kind of performance improvement you can get when you STC Your Brain.

Any other questions? We are glad to help!

[jetdriven]

Fascinating!