LOP Operations

[Meshach]

I recently acquired a ‘70 F. I’ve been hearing a lot about running lop but frankly don’t know anything about it. Training for PPL I was taught to lean till the engine ran rough then richen slightly. Where exactly will that put me? 
    And what all do I need to try running lop? Special gauges? Injectors? I believe my plane is mostly stock. 

[Danb]

Basically your running LOP as you explained. Without an engine monitor you don’t know for sure the amount of LOP. Your running 

[MikeOH]

It doesn’t look like you have an engine monitor so you can’t really determine how far LOP you are. Many IO360s, including my 70F, have good fuel balance between cylinders. Consequently, if I lean until rough the engine will be so far LOP that I won’t be making much power. You certainly won’t hurt anything by trying it above 5000 DA. If you have a fuel flow gauge then just  lean to around 8.5-9 gph in cruise(WOT, 2500) That should put you under 70% power LOP.

[EricJ]

+1 that you need an engine monitor to really know where peak is and how far LOP or ROP you are from that.   Without an engine monitor you can do as you described and run just rich of roughness, which will be LOP on your engine.   Lycomings are fine with stock injectors.

You should have an EGT gauge that just measures one cylinder, and if you have a fuel flow meter you can use those to get a decent idea of where the engine likes to run.   Monitor your CHT gauge just to make sure whatever you're doing isn't overheating it.

 

[Fly Boomer]

3 hours ago, Flying Dutch said:

I recently acquired a ‘70 F. I’ve been hearing a lot about running lop but frankly don’t know anything about it. Training for PPL I was taught to lean till the engine ran rough then richen slightly. Where exactly will that put me? 
    And what all do I need to try running lop? Special gauges? Injectors? I believe my plane is mostly stock.

To run LOP, all cylinders must be on the lean side of peak.  Only way to tell for sure is with a per-cylinder engine monitor.  As you lean, once the LAST cylinder goes to the lean side, then you are "lean of peak".

[PT20J]

On a Lycoming IO-360, if you lean until it gets rough and then enrich slightly until it just gets smooth you are LOP.

[0TreeLemur]

19 minutes ago, PT20J said:

On a Lycoming IO-360, if you lean until it gets rough and then enrich slightly until it just gets smooth you are LOP.

I read that this technique was used with success by WWII fighter pilots to extend range without engine monitors.  Introduced by a bold pilot (don't remember the name) who bucked the prevailing "LOP is BAD" thinking.   I've played with this technique recently.  Compared to the lean-find function on my engine monitor, it works out to run my IO-360 about 60-70F LOP in the leanest cyl., with the richest being about 30-40F LOP.   So, I can run LOP pretty well by leaning to roughness, richening to smooth it out, then richen a tad more.  The GAMI spread on my engine is 0.2 gph, which means the fuel injectors are well matched.

@Flying Dutch an engine monitor is a great first upgrade for a "new to you" Mooney to help you manage your engine better.   If you get a certified primary engine monitor, it can replace your Manifold Pressure and Tach gauges, plus your instrument cluster.  This puts all engine info on one screen.  Gives you much greater situational awareness in the case of a rough running engine at runup during the mag checks or in flight.  I've dealt with both.  

I can run my IO-360 above 10kft on about 7.5 gph LOP and get 145 TAS.  That's efficiency.  Below 65% power, mixture setting cannot harm the engine.  Too rich and you'll foul plugs.   Too lean and it just stops making power.  

[EricJ]

1 hour ago, 0TreeLemur said:

I read that this technique was used with success by WWII fighter pilots to extend range without engine monitors.  Introduced by a bold pilot (don't remember the name) who bucked the prevailing "LOP is BAD" thinking.

Charles Lindbergh did a lot of that with the military during WWII, especially in the Pacific theater.   The mission that intercepted Admiral Yamamoto was made possible partly by Lindbergh's training with the P-38 squadrons to extend their range.

[Meshach]

Thanks for all the info. I have what I believe is an EGT gauge just left of the yoke. If I lean to roughness and only richen till it’s smooth again, the gauge swings up pretty fast. If I richen about a half an inch more, it cools right back down… 
 

What engine monitor would you recommend?

[201er]

58 minutes ago, Flying Dutch said:

the gauge swings up pretty fast. If I richen about a half an inch more, it cools right back down… 

That’s peak

[Meshach]

So if I richen till it’s cooler, I’m ROP?

[Danb]

Your getting richer without a monitor you not sure how rich or lean you are. Obviously if you enrichen it until smooth your probably a little lean of peak. As long as you’re making good power you’ll be ok there. I’d try to be rich on takeoff, lean on taxiways then do your leaning after climb out. 

[201er]

1 hour ago, Flying Dutch said:

So if I richen till it’s cooler, I’m ROP?

Yes. But just on that cylinder. No way of knowing where the others are without an engine monitor. So the guessing method is to either stay well rich or well lean of peak and hope the other cylinders fall in line. 20-50 rich of peak usually correlates to the highest cylinder head temperatures and highest pressures as well. 

[Fly Boomer]

2 hours ago, Flying Dutch said:

So if I richen till it’s cooler, I’m ROP?

Eventually.  If you start well LOP on all cylinders as indicated by your engine monitor, and begin to richen, at first the temperatures rise toward peak.  As you continue to richen, one by one, each cylinder will cross peak to the rich side of peak, and then all cylinders will get cooler and cooler as you get further away from peak.

[PT20J]

From the IO-360 Operator’s Manual….

[KSMooniac]

Every pilot and especially owner should take the www.advancedpilot.com seminar and really learn what is going on with the red knob of death. There are a lot of wrong answers on this thread already, and those that have really learned the topics know.

There is too much to cover in forum format to really teach the fundamentals.

Sent from my LM-V600 using Tapatalk

[MikeOH]

12 minutes ago, KSMooniac said:

Every pilot and especially owner should take the www.advancedpilot.com seminar and really learn what is going on with the red knob of death. There are a lot of wrong answers on this thread already, and those that have really learned the topics know.

There is too much to cover in forum format to really teach the fundamentals.

Sent from my LM-V600 using Tapatalk
 

Really?  I'd be very interested in what is so wrong with what has been posted?

This is NOT that complicated; too much to cover??  The 'red knob of death' comment is a bit of hyperbole, IMHO.  Sure, you can ham-fist to damage but unless it's a turbo you really have to work at it.

[KSMooniac]

Red knob of death is very much meant to be facetious. Many are afraid of moving it, clearly you're not. But seriously, I took the class in person over 16 years ago, a few months after purchasing my Mooney and learned more there in 2.5 days than in many is my semester-long engineering courses. It is that good! Currently, I believe only the online version is offered, and it is worth every penny. It covers all aspects of piston engine ops, not just LOP. Fundamentals of combustion, engine monitor use, troubleshooting, emergency procedures, etc.

I used my knowledge from that class to successfully diagnose a failed plug on a fuel stop many years ago, because I had the education and an engine monitor that I knew how to use. It turned a significant vibration on run-up into a 30 minute nuisance because I knew what was wrong, versus taking it to a mechanic and simply saying "rough run-up" and paying for diagnostic work. That could have set me back hundreds of dollars in just one instance.

I'm tired of trying to correct erroneous info on the web and instead try to lead owners to the best fountain of knowledge there is on this topic. The technical info is of course top notch, but beyond that, the quality and effectiveness of the teaching materials are even better. They are able to get through to any average pilot, not just technical folks.

/Off soapbox

Sent from my LM-V600 using Tapatalk

[MikeOH]

@KSMooniac

I have no issue with learning MORE; I have no issues with your first paragraphs and pitch for APS in your last post.

But, to jump in and claim 'misinformation' without any specifics...then respond with "I'm tired of trying to correct erroneous info" seems a bit weak.

You brought up "there are a lot of wrong answers on this thread" and then run when asked what they are???

[KSMooniac]

"On a Lycoming IO-360, if you lean until it gets rough and then enrich slightly until it just gets smooth you are LOP."

May or may not be correct. As a blanket statement, it is wrong, though.


"  Monitor your CHT gauge just to make sure whatever you're doing isn't overheating it."

Partially good advice, but not sufficiently correct either to avoid potential engine damage. You can't lean solely by CHT and be sure you're not at a bad mixture setting that could be really hammering your engine. For example, leaning to 375 degF in the summer in KS versus the winter in Alaska results in two very different power settings. A pilot without the background might think 375 is just fine because the Lycoming redline is 475, right? In reality the internal cylinder pressures could be extremely high and causing damage to the pistons, plugs, valves, etc.


Sent from my LM-V600 using Tapatalk

[ArtVandelay]

On a Lycoming IO-360, if you lean until it gets rough and then enrich slightly until it just gets smooth you are LOP.

Only true if it’s reasonably balanced, if you have a cylinder running far more rich than others, that cylinder could still be running ROP. An engine monitor is needed to determine this.

[ArtVandelay]

"  Monitor your CHT gauge just to make sure whatever you're doing isn't overheating it."

Partially good advice, but not sufficiently correct either to avoid potential engine damage. You can't lean solely by CHT and be sure you're not at a bad mixture setting that could be really hammering your engine. For example, leaning to 375 degF in the summer in KS versus the winter in Alaska results in two very different power settings. A pilot without the background might think 375 is just fine because the Lycoming redline is 475, right? In reality the internal cylinder pressures could be extremely high and causing damage to the pistons, plugs, valves, etc.

We don’t have instrumentation to give us ICP, so we use cylinder temperatures as a proxy. The other indication would be the sound of the engine running rough, and enriching the mixture should your first attempt to fix it. But if ICP are extremely high, the CHTs are going to rise well above 375°, Busch has shown engine monitor traces of CHTs quickly rise above the top limits of the engine monitor (600° IIRC).

[A64Pilot]

There are a few “Bottom lines” that I think should be stated, and maybe discussed.

According to Lycoming below 75% power you can run any mixture you like and it won’t hurt anything, personally I use 65% for a couple of reasons, it adds additional cushion and Lycoming has published for maximum engine life cruise at 65% or below power, plus most myself included a large reason for LOP is economy, and economy is best below 65% power. So other than being in a hurry, I can’t see any reason to cruise above 65% power myself, others say I bought a Mooney for speed and slowing down is stupid. I see their logic, just I’m not in that big of a hurry. 

(NA motors only) Blown motors are a whole nuther thing.

Spending thousands on engine monitors and special injectors, fine wire plugs certainly doesn’t hurt but isn’t needed, because if you only aggressively lean at 65% or less power then you can’t hurt anything and all that expensive stuff isn’t necessary.

People as in a large percentage of pilots have been running LOP in engines that would since before WWII, it just wasn’t given a name etc until it started being marketed. Many or most engines won’t run LOP, most were running just fine at or very close to peak, for longer than most of us have been alive.

In my opinion, and this is just an opinion, but I think as a new pilot you should spend that money on fuel and fly very often, get instrument training if you haven’t already and practice, practice, practice, run 65% of less in cruise, continue to lean as you were taught and put all that special engine ops training and big bucks for special instrumentation off until you have become a Master Aviator and can fly in hard IFR, land in excessive crosswinds etc.

Oh, and for high power run very rich, in my world in the flatlands that’s full rich, but your runway may be at higher than my normal cruise altitudes so I won’t say full rich.

Another bottom line, you can’t be TOO lean, engines are hurt by not being rich or lean enough, but if you stay very rich until 65% you can’t hurt anything and your engine will last a long time, there is nothing wrong with the way you were taught, I’d just add be at cruise power (65% or less) before you do it. It’s a very good KISS way of leaning, and KISS isn’t stupid.

Most engines won’t run LOP, the Lycoming IO-360 is the poster child of LOP, so I’ll bet lunch that your bone stock IO-360 if in decent shape will run LOP just fine, but regardless even if it won’t leaning the way you were taught if below 75% power, is fine. It was after all the way most everyone leaned for the majority of the time these engines have been operated, now if theses engines were a new design, then it’s likely that a new way of operating them would be required, but face it, we fly behind our Grandfathers engines, literally.

[KSMooniac]

I can also make the argument that it is more important to run LOP if you don't have an engine monitor! How many strange looks am I getting after making that seemingly silly statement?

Scenario: you don't have a monitor and typically cruise ROP with CHT and EGT on #3 only. You set cruise power at 100 ROP and everything is smooth. All good, right? What if you have an induction leak on #1 or 2 or 4, such that it leans that cylinder mixture to 40 ROP? You're ROP on all of them, so the power from the lean cylinder doesn't reduce that much, and might actually increase, but the ICP and CHT will go way up. But you wouldn't feel it in the cockpit or know it with stock instrumentation. And we typically don't proactively test for induction leaks at annual. You don't catch this on a ground runup either, unless it is really severe and won't idle normally.

It's quite different if you're running LOP, though. The induction leak would push that cylinder further LOP and it's power output would drop noticeably and produce a vibration that would get your attention, especially when you know that it previously did not "run rough". You could adjust mixture and quickly diagnose the problem, but not which cylinder is leaking. If you can run LOP successfully, you know your engine has good ignition (plugs, wires, mags), no induction leaks, and good fuel: air mixture on every jug. I do that with stock components on my 360... so I haven't bought GAMIjectors and feel compelled to get others to buy them to make myself feel better. They are a fantastic company, though! I had to fix induction leaks on my engine after assembly, move injectors around, etc to get there, but now my GAMI spread is 0.0 GPH.

So that is an explanation of how normal LOP ops can act as a surrogate engine monitor! But I still feel having a good modern monitor (such as a JPI EDM 700 or similar at a minimum) is vital for all of us. We have a single engine that we depend on. Treating it poorly or not catching anomalies quickly can cost significant dollars at a minimum, or lead to a forced landing/potential crash at worst. Why would you not do everything in your ability to prevent that outcome? There is way more to it than saving a little fuel ...

(I said I was tired of explaining this stuff after 16+ years, but I got sucked back in to the argument anyway. )

Sent from my LM-V600 using Tapatalk

[PT20J]

4 hours ago, ArtVandelay said:

Only true if it’s reasonably balanced, if you have a cylinder running far more rich than others, that cylinder could still be running ROP. An engine monitor is needed to determine this.

True, but generally the four banger Lycomings are pretty well balanced. The intake tubes are all about the same length and run through the sump which warms the air improving the vaporization of the fuel before it gets to the cylinders. The carbureted O-320 in a Piper Warrior will run LOP and the procedure is in the POH.