ROP vs LOP

[Brian Scranton]

I've tried--I really want to--but she won't let me. IO-360A1A with a RayJay. I'll run 25'' and 2400rpm (and I have a GEM610 which works nicely but no where near a JDI)--I'll lean by TIT and I'll see the TIT peak at 1520 or so by the time the first cylinder begins to come back down. By the time I get to the 3rd or 4th cylinder, she gets pretty rough. No GAMIs. No FF. 

[N6758N]

21 minutes ago, gsxrpilot said:

 

  Any gasoline piston engine will run LOP as long as all cylinders can be burning fuel at close to the same rate.

Not disagreeing with you Paul, but it is more difficult in a carb'd engine as you said. From a design standpoint, if you've seen the intake assembly on Lycoming you can understand why these engines are much more difficult to run LOP. I think you're a lot more likely to do damage in a carbureted engine running LOP than in a fuel injected engine. That being said, I can attest to the power of MS and how I continue to learn new things everyday. I'm not above trying LOP in my 'C myself after reading you and Hank's testimonies. 

[gsxrpilot]

1 minute ago, N6758N said:

Not disagreeing with you Paul, but it is more difficult in a carb'd engine as you said. From a design standpoint, if you've seen the intake assembly on Lycoming you can understand why these engines are much more difficult to run LOP. I think you're a lot more likely to do damage in a carbureted engine running LOP than in a fuel injected engine. That being said, I can attest to the power of MS and how I continue to learn new things everyday. I'm not above trying LOP in my 'C myself after reading you and Hank's testimonies. 

To be fair, I was a bit concerned about getting it right as well and not doing any damage. And it is more difficult in a carbureted engine. So while I tried and worked out the proper method to get LOP, I was always above about 8000' where the engine is making much lower power and therefore virtually impossible to do anything to hurt it.  Once I worked out the sequence, which for me involved pulling the throttle back as much as possible without reducing MP and therefore closing the enrichment circuit, I could run LOP easily at all altitudes.

[Cyril Gibb]

Here's the Lycoming leaning graph which shows 50 ROP to create the highest CHTs.  Way leaner (if possible) or way richer would be kinder to your cylinders.

 

[N6758N]

Just now, Cyril Gibb said:

Lycoming leaning chart shows 50 ROP the highest CHTs.

 

Not saying it is correct, but for a long long time Lycoming recommended 50 ROP as the optimal mixture setting...Maybe I am just old school, I'll be honest though, after readings today's postings, I will probably not be running mine 50 ROP anymore. I try not to be as stubborn as some of the other folks on MS and I know I am a relatively inexperienced when it comes to flying Mooneys, a lot of my knowledge comes from my days of wrenching and thus I tend to follow the manufacturer's instructions more closely. 

[201er]

4 minutes ago, N6758N said:

Not saying it is correct, but for a long long time Lycoming recommended 50 ROP as the optimal mixture setting...Maybe I am just old school, I'll be honest though, after readings today's postings, I will probably not be running mine 50 ROP anymore. I try not to be as stubborn as some of the other folks on MS and I know I am a relatively inexperienced when it comes to flying Mooneys, a lot of my knowledge comes from my days of wrenching and thus I tend to follow the manufacturer's instructions more closely. 

Actually I'm not sure it was every Lycoming that recommended 50ROP. I could be wrong, but I think Lycoming was recommending 100ROP for best power or 0/Peak for best economy. Then some  instructors or whatever, decided to average the two out and came up with 50ROP thinking it was a good compromise of the two (and in reality the absolute worst thing).

[gsxrpilot]

This chart is a little easier to read/understand and applies to both Lycoming and Continental engines.

[Garryowen]

 

17 hours ago, gsxrpilot said:

This chart is a little easier to read/understand and applies to both Lycoming and Continental engines.

 

That's a nice chart. Where would the "red box" fall on it that M Busch talks about? Is it between the 50 rich and 50 lean or does it change with % hp?

[gsxrpilot]

12 minutes ago, Garryowen said:

That's a nice chart. Where would the "red box" fall on it that M Busch talks about? Is it between the 50 rich and 50 lean or does it change with % hp?

Try this link and you can push the throttle and see the red box change. https://www.advancedpilot.com/redbox.html

 

[N6758N]

2 minutes ago, gsxrpilot said:

Try this link and you can push the throttle and see the red box change. https://www.advancedpilot.com/redbox.html

 

Okay Paul, I'll risk sounding like an idiot here. I am not a huge Mike Busch fan (not that I discredit what he does) but besides that point, what is the 'red box'? I'm assuming its the danger zone of engine operation parameters?

[gsxrpilot]

10 minutes ago, N6758N said:

Okay Paul, I'll risk sounding like an idiot here. I am not a huge Mike Busch fan (not that I discredit what he does) but besides that point, what is the 'red box'? I'm assuming its the danger zone of engine operation parameters?

No worries Terry. The "red box" or on some charts called the "red fin" is an area of extreme Internal Cylinder Pressure and corresponding high CHT's. It's not recommended to run your engine very long in this area. High ICP and CHT's are, according to John Deakin, George Braly, at GAMI, the leading cause of short engine life. Mike Busch, who has supposedly attended the APS class three times, tends to ignore the ICP issue and focus solely on CHT. 

If you have time, and are inclined to do some reading, on this page is a Download button for John Deakin's articles. It explains it all very nicely. https://www.advancedpilot.com/tech.html

One nice thing about flying a C or any normally aspirated engine up high, is that over about 8000 or certainly 10000 ft. you're not making enough power to create a red box. You can do anything you like and not worry about over stressing your engine.

[N6758N]

Just now, gsxrpilot said:

No worries Terry. The "red box" or on some charts called the "red fin" is an area of extreme Internal Cylinder Pressure and corresponding high CHT's. It's not recommended to run your engine very long in this area. High ICP and CHT's are, according to John Deakin, George Braly, at GAMI, the leading cause of short engine life. Mike Busch, who has supposedly attended the APS class three times, tends to ignore the ICP issue and focus solely on CHT. 

If you have time, and are inclined to do some reading, on this page is a Download button for John Deakin's articles. It explains it all very nicely. https://www.advancedpilot.com/tech.html

One nice thing about flying a C or any normally aspirated engine up high, is that over about 8000 or certainly 10000 ft. you're not making enough power to create a red box. You can do anything you like and not worry about over stressing your engine.

Thanks Paul! Despite my aviation maintenance background, I am clearly behind the times on this stuff! Most of my flying, especially XC trips is at 10000ft or above if I can get away with it, so the red box won't be an issue for me. I focus on CHTs pretty intently as my C gets hot quickly on takeoff without careful considerations to airspeed and mixture. I think I am going to dive into my doghouse again this upcoming annual and see if there are any areas that may be improved to aid in LOP operations.

[Garryowen]

1 hour ago, gsxrpilot said:

Try this link and you can push the throttle and see the red box change. https://www.advancedpilot.com/redbox.html

 

Thanks for the link. Not to sound cliche, but pictures are worth a thousand words. 

[Browncbr1]

1 hour ago, N6758N said:

Thanks Paul! Despite my aviation maintenance background, I am clearly behind the times on this stuff! Most of my flying, especially XC trips is at 10000ft or above if I can get away with it, so the red box won't be an issue for me. I focus on CHTs pretty intently as my C gets hot quickly on takeoff without careful considerations to airspeed and mixture. I think I am going to dive into my doghouse again this upcoming annual and see if there are any areas that may be improved to aid in LOP operations.

at 10k and above, your fine at 50 ROP...   there isn't enough atmospheric pressure up there to hurt the engine no matter what you do.  At that altitude, you are definitely making less than 60% power..  probably around 50% power actually..  Just be mindful of the red box below about 8000 DA for WOT/high RPM.

 

Also, that red box link from above really should be sort of yellow or pink at the left and right extremities of where the red box is drawn.  

[bonal]

On ‎5‎/‎1‎/‎2017 at 9:29 AM, N6758N said:

You never want to run the engine at peak because that means your cylinders are at their hottest, which is no good for longevity of engine parts. Hence why you should be either lean of peak or rich of peak. In a carbureted C model like you and I have, LOP is NOT an option. Because of the design of the air intake/fuel system on the O-360 the fuel can not be evenly distributed enough to run LOP. I run mine right around 50 ROP.

So to be clear and since I am not using a fancy monitor I use the lean to rough then rich to smooth and that results right at 20 to 30 degrees based on what the incraments on my factory gauge represent per my POH so I am LOP and was just wondering about running at peak which according to the tables shown in this thread am still better off than being ROP. My cylinder temp #3 in cruise is around 360 degrees. The reason I wondered about running at peak is it makes for a very simple process since I only have the factory EGT gauge (easy to tell) when I reach peak temp. But I would have to say that my carb engine is very smooth at just lean of peak. Different opinions here so I will just keep what makes the most sence a smooth running engine which just happens to be a tad LOP

[N6758N]

Just now, bonal said:

So to be clear and since I am not using a fancy monitor I use the lean to rough then rich to smooth and that results right at 20 to 30 degrees based on what the incraments on my factory gauge represent per my POH so I am LOP and was just wondering about running at peak which according to the tables shown in this thread am still better off than being ROP. My cylinder temp #3 in cruise is around 360 degrees. The reason I wondered about running at peak is it makes for a very simple process since I only have the factory EGT gauge (easy to tell) when I reach peak temp. But I would have to say that my carb engine is very smooth at just lean of peak. Different opinions here so I will just keep what makes the most sence a smooth running engine which just happens to be a tad LOP

You are running LOP if you are leaner than when you hit peak EGT, you are ROP if you are enrichening once you hit peak. Personally I think running at peak all the time will wind up hurting the exhaust system in the end. I would say you are better off at 20-30 ROP or 20-30 LOP.

[peevee]

I'm still trying to get LOP ops down. Tried it today at FL180. Tried 31" which is about 70% and tried 30" which is about 65% when running ROP. Could not get the TIT as low as I'd like (1600) before the engine woudl start to stumble. Didn't care to go lower power, had place to be. Frustrating. Gami spread was .2 IIRC. Will keep experimenting I guess but I would have thought at least 65% power would work if not 70.

[bonal]

Just now, N6758N said:

You are running LOP if you are leaner than when you hit peak EGT, you are ROP if you are enrichening once you hit peak. Personally I think running at peak all the time will wind up hurting the exhaust system in the end. I would say you are better off at 20-30 ROP or 20-30 LOP.

then I will keep doing what I have been which is around 20 to 30 LOP

[Brian Scranton]

My old school A&P trashes the idea of LOP ops...he says he's seen all the data from Mike, John and APS but he also has 40+ years of looking at lots of different engines that have been run lots of different ways. He believes that LOP have one major disadvantage, the loss of protection that comes with copious amounts of lead only found in copious amounts of fuel. He thinks by limiting the lubricating, protective aspect that 100LL has on the metals in a cylinder, we're doing far more harm on the life of the engine components. He agrees, LOP may be 50 degrees cooler, and he agrees that less fuel equals longer ranger and less $, but he's seen a shit ton of valve, ring and compression issues as a result. Ready....DISCUSS! 

[KSMooniac]

Lead does not lubricate/cushion/protect anything. It only leaves deposits in places that causes trouble. All of the valve and ring trouble he is talking about is caused by lead gunking up the parts.

Sent from my LG-LS997 using Tapatalk

[Brian Scranton]

2 minutes ago, KSMooniac said:

Lead does not lubricate/cushion/protect anything. It only leaves deposits in places that causes trouble. All of the valve and ring trouble he is talking about is caused by lead gunking up the parts.

Sent from my LG-LS997 using Tapatalk
 

Well, shiiiiit. I must have totally missed his point--maybe he was referring to knock or detonation. I'll now have to dig deeper. He was rambling pretty good. 

[KSMooniac]

He's ranting from a position of ignorance. He's trying to say things are failing because of LOP ops went it is the exact opposite.

He may be confused by seeing engines not run lean ENOUGH, because the hotter temps will accelerate the deposits from a ROP setting. LOP is cooler and cleaner...less lead going in, lower temps to reduce deposits.

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[N6758N]

Lead does lubricate and cool, that is why it is added to aviation fuel...

[Hank]

8 minutes ago, N6758N said:

Lead does lubricate and cool, that is why it is added to aviation fuel...

I thought lead was used as a knock suppressor rather than a lubricant. 

[KLRDMD]

16 minutes ago, N6758N said:

Lead does lubricate and cool, that is why it is added to aviation fuel...

Lead is in aviation fuel primarily to increase octane.