The guy in the red shirt lost credibility as soon as he mentioned shock cooling! It's a myth that was dispelled long ago. His explanation of cracking cylinders during descent after cruising LOP makes no sense either. As did his LOP fuel burn calculations for flight planning. As for why the debate gets heated: one side understands the combustion science and what is happening inside the engine. The other relies on ideas that sound good on the surface, but lack the scientific data to back them up. The guy in the middle seems like he gets it, but couldn't articulate it completely. The reason to run LOP is simple...the engine runs cooler and cleaner that way. Is it worth a few knots of speed to do so? That's up for the owner to decide. And if you're going to run ROP at high power settings, 50-100 ROP probably isn't rich enough. It probably takes 125-150 ROP to stay outside of the red box and in a safe area.

Wow, we look SERIOUS in that thumbnail image! 😁

Inconceivable. Two people with different points of view on a topic are able to engage in a rational discussion about the issue......I wonder where else in life we could benefit from such a revelation?

Great show. Recommended reading: Mike Busch on Engines. Very good and fun book to read.

23:46 Martin is 100% correct on this discussion of the dangers of the old school leaning method. Nicely done. Thx. Wayne

Sorry guys. LOP doesn't mean you are running at max power, nor does it lead to shock cooling. CHTs are always LOWER than the equivalent HP at ROP. LOP means you are completely burning all of the fuel - no buildup on your valves to cause premature wear. Squeaky clean exhaust. You guys need to go see Mike Busch. I've been doing it for years. If you are cracking cylinders, you have other problems. You CANNOT damage an engine by being too lean. It will quit running if you are too lean, but it will never damage the engine. Not lean enough (peak power setting) is the riskiest place because of detonation at the higher combustion pressures. In fact, the old school method of lean until roughness and enrichen just slightly is VERY LIKELY to put you into the highest internal combustion pressure range unless you really understand the power curves of your engine. In a normally aspirated Lycoming engine, once you reach about 7500ft, firewall the baby and run at peak power - if you have proper fuel and induction systems, there is no way you'll see any detonation, and again, the engine will be squeaky clean and happy for a LONG time! Shove a borescope into your cylinder head after a season of running lean of peak - it will be shocking how clean it will be in there. I can go faster on long trips by running slower / LOP to reduce the number of stops.

Very nice session... one big item not emphasized enough in favor of LOP is significantly cleaner cylinders vs ROP... because in ROP you have an excess of fuel, which means that many deposits, including lead, collect in the cylinders. Wayne

Continental engines are required to run lean of peak in my Malibu a run lean of peak and I don’t reduce power in the decent from the flight levels. Most important thing is manage your decent and power handling. I agree with Martin.

Thanks, Dan. 👍 Great panel! 😎 My takeaway is the stronger option of planning ROP, but actually flying the disciplined ability of LOP. Pilot’s discretion, and no doubt the mission profile is just one factor out of multiples to carefully consider. Bottom line: treat the engine right. CAVU 🇺🇸✈️

Great discussion. I attended the first ever Advanced Pilot Seminar and worked for an engine shop for 11 years. The need for GAMI's on Bonanza/Baron engines is an induction imbalance built in.

what a great show, I don't even go on Netflix anymore, this is so much better, you guys and girls do a great job, and everyone in aviation loves it and are watching. Thank you

Dan, I liked your delicate dance into your statement of "shock cooling is a myth"....

Just because fuel efficiency is a benefit of LOP doesn’t mean you carelessly rely on it and it becomes a dangerous event. He was just stating an objective benefit.

Excellent, honest discussion. Very good points to be made on both sides of the discussion and presented fairly.

You cannot detonate an engine if you are at 75% or less power. Also, cylinders are cooked by excessive heat (400+ degs). There is much less chance of doing this when running lean of leak.

Just remember to PICK ONE! Rich or lean you are safe. Anything in between and you're asking for trouble.

Interesting and important conversation. I became a PPL in 2002. Back then we had no monitoring in the plane I flew.(C172 180 HP constant speed prop) I got up to altitude, puled the mixture until the engine failed and pushed it back in slightly until it ran smooth.

Thanks guys, it helped a lot

How is this a "smackdown", Cletis? It's mechanical engineering, the advantages of lean-of-peak are NOT up for debate, it's science ...

Red shirt needs to read Mike’s book and get educated on the subject.

Could you take questions from the spectators next time perhaps? They seem smart and might have a valid question or something interesting to add. Thanks for this video. Really interesting format of discussion!

In my naturally aspirated engine, continental talk about “keeping temps up to keep oil temp up to burn off contaminants, etc”…ROP, “385F all day” is the designed run all day temp. I used to like to run LOP on my IO520 often 310 sometimes less , sometimes 325……..but i can not get it to 385 LOP at cruise…..my 800 hr engine had spalling and other issues after a prop strike inspection so we overhauled it…..so LOP, what is the recommended CHT min range to allow the engine to get to in a IO 520?…..320F may be good for head strength/wear but may have other negative consequences?

well, i was interested, but the "ROP" guy started straight in with logical fallacies and straight up bad science/engineering myths. You guys should get Mike Busch on here some day. His engine operation and maintenance practices videos with the EAA are an absolute goldmine of information backed up by hard scientific data collected directly in engine test cells. I don't plan my legs based on best-observed fuel flow, i plan based on the book numbers, which are absurdly rich. "Shock cooling" is not a thing, unless you are dunking your plane in a swimming pool after each flight. even if "shock cooling" were a thing, running cooler engine temps on the lean side would make that LESS of a problem, not MORE running rich enough to cool the engine results in fuel condensation on the cylinder walls during the low-pressure cycles on intake stroke, as well as a higher volume of raw fuel in the blowby to the crankcase, which compromises cylinder wall lubrication and accelerates wear.

Why are my shoulders so shrugged up?😂

Enjoyed the debate...thanks Guys now my 2 cents.....the discussion is what are the advantages for each as it pertains to the engine performance and longevity ......forget range, fuel costs, speed. If you want get someplace 20 mins sooner on a 2 1/2 hrs. trip and spend more on fuel and run your engine less efficiently go for it, but that's flight planning not engine performance, but the discussion is what effect each has on engine performance/life....and it seems to me LOP is the best way to go....best for engine efficiency and longevity....cooler CHT and EGT's seem to be the most important part of this discussion. sacrificing a SLIGHT loss of speed is well worth getting to TBO or beyond .....thanks again

Great discussion. What happens to the engine flown by two or more pilots with different engine management styles? Hopefully we will see technology evolve to the point of having affordable fadec systems like Trent Palmer has.

Thank you for breaking the topic down for even us non pilots can understand 🙏

Cirrus does a good job on this topic in one of their videos about LOP vs ROP in a way that's really characterized as Best Economy vs Best Power, and then they show you how to do both, according to the POH. It's not either this or that, but based on what your flight profile requires, economy or speed. They have another video for the Turbo or Turbo Normalized engines which ONLY have LOP charts because the turbo engine is able to run cooler at a higher power setting burning less fuel with fewer emissions, so there's no procedure in the POH for running LOP for the turbos.

EGT is nice to know but that is outside the engine, -Mike Busch. I fly a carbureted engine with a digital engine monitor, EGT-CHT on all four. Helps me keep the CHTs in line.

I have a Lycoming powered Piper Arrow. How do I run LOP? I have % power values on my manifold pressure fuel flow gauge. Is leaning to 55% power LOP? My Arrow has not stepped into the 21st century yet, I get an engine analyzer next month, so I am still playing with 1930’s technology.

Does fuel injected vs carbureted matter when deciding to run LOP?

I think a good summary of the debate is that running LOP is a very advanced technique, however there are plenty of benefits, but inexperience with the technique can be costly.

And I watch Martin on you tube, even if I'm not and general aviation pilot anymore.

Very interesting subject ever for a non pilot. Thanks all.

9:12 spend 15 extra dollers to get there an hour sooner? I don't think this math adds up. unless your gaining an increadible amount of speed burning a another gallon an hour.

It wasn't mentioned I don't think but neither of these guys have turbo'd Bonanzas. The LOP concept makes a world of difference when you have a turbo charged engine. The NA engines benefit from LOP for range and cleaner cylinders but not like a turbo engine where you can also boost back the power loss from going LOP when flying higher altitudes and gain some speed back..best of both worlds..

Oh, hold on, let me get a beer, this is gonna be good!

So if i have just the basic avionics, single EGT and CHT indications, may ROP be safer than LOP?

Flying my trainer 172SP with IO360 and G1000, my CFI just had me lean to 8GPH.. If you flipped over to the EGT/CGT screen, it was pretty damn close to where you needed to be.

There are lots of rival gangs.... highwing vs lowwing, nose gear vs conventional, etc

Add running over-square and under-square to the discussion and create a real donnybrook.......

9:10 you aren’t going to turn a 7 hour flight into a 4 hour flight.. but I get it. Go fast in the headwind, slow down in a tailwind.

I wish someone would discuss how internal combustion engines work. You have a given mass of air and a given mass of fuel to burn. Together that creates a given amount of energy. How is LOP different than just decreasing the available mass of air (with the throttle) and adjusting the mixture to achieve the same result (on the ROP side)? If you say you lose 10 kts running LOP, how is that different than a lower MP/throttle setting (ie smaller mass of air)? Does that also equate to lower CHT? Seriously, that’s the extent of my knowledge. :)

if you watch the Leaning Basics KZfaq video by Mike Busch on the Savvy Aviation channel, It will teach you all about the need for LOP, and how Embry Riddle was destroying their 172's engines. Savvy Aviation is another good channel for serious pilots who want to get educated on real life aircraft operations. They also have a good video there about deciding when to overhaul your engine.

I disagree about Cirrus training revolves around LOP. I have done all of my training in a Cirrus and have 1000 hours in type. Been trained but 2 platinum CSIP's as well as a Cirrus Factory Pilot when I purchased my new airplane and NEVER was I instructed to fly LOP. In fact quite the opposite. I was told that both Cirrus and Continental want the engine flown ROP. I love your videos and appreciate all the information and content you provide. I just wanted to clarify what my experience has been vs. the statements made in this video. Thanks

I'm like John, I have the G500txi EIS on my center PFD

NOT running ROP any time cabin heat is used should have also been included as this can introduce Carbon Monoxide into the cabin with a single pin hole leak in the heat exchange.

LOP: owners, miles per gallon ROP: renters, dollars per hour

Just fly higher. Beyond 10,000 ft, LOP vs ROP is a moot point. The engine is operating 60% or less and you’re well beyond the “red zone”

I did my private in a C-150E during the mid-60's. I was one of those who got their hands slapped if the mixture wasn't "permanently" firewalled. (But don't try that around Santa Fe ---- Ask the guys from AOPA during our last Fly-in how many Bonanzas touched down and found their engine come to a dead stop because they flooded on touchdown [8000' Density Altitudes])

I like red shirts math. Plan for 2.5hr range, run ROP for the extra 5-8kts, and save 1hr. Seems legit. When I plan for 1100nm trips and do the math between ROP and LOP air speeds I can’t even save an hour for the trip. Only way I can save an hour over an 1100nm flight is to run at max continuous power at the cost of nearly doubling fuel burn.

As a non-pilot lover of aviation I'm amazed that manually adjusting fuel mixture is still a thing in 2020.

A couple of important points: everyone who runs ROP should get the equipment and know-how to run LOP so they can extend their duration in emergencies, such as diversions or long holds. Second, it should be noted that there is a range of CHTs that work, and too high or too low is bad, for different reasons.

Can’t believe you guys didn’t comment on stoichiometric. It is the ideal combustion mixture, however it’s also the peak cylinder pressure where you don’t want to run. Some of the comments made make the issue way more complicated than it actually is.

I run twin turbo io 550e on my lancair. I am also a mechanical engineer of 40 years based in engine development. I can come on your show and set the record straight. It is all about detonation! I have developed a detection system to show the pilot when he is in detonation.

Two schools of thought which the mission will dictate to the informed pilot what he will do. I wish my instructor had spent some time on this when I was learning to fly. Took me years to really understand how it worked.

LOP has another benefit. It drastically reduces CO emissions so if there is an exhaust leak you are less likely to get sick.

Gas/Air ratio in the cylinder combustion. * Timely reminder about synthetic oils at or above max operating temp. Will the alloy end up in the oil filter. * I like Martins protocol of reserving 1 hour of gas (but, adding extra weight in performance planning). * If running a piston engine regular lean of peak, causing higher EGT, TIT, CHT: oil would be of increased viscosity, for heat? 💥🤾‍♂️

I like what Martin has to say. Run LOP to save money and the environment. If you aren't willing to do the research and be diligent in the cockpit, run ROP.

It’s crazy to me that in 2024 we’re still operating these antiquated engines with pilot controlled mixture. Continental and Lycoming need to catch up with Rotax and implement FADEC which automatically controls mixture. The Rotax iS engines go LOP or ROP automatically when appropriate. Too many pilots are unfamiliar with how to stay out of the red box / red fin on these old technology engines, so the end up damaging their engines. Like the one gentleman mentioned, he spends more time looking at his engine monitor than looking out the window. That is not a good thing. An engine computer should handle the mixture and let the pilot concentrate on flying.

Leaning until you hear an RPM drop then increase a little bit is leaning for maximum RPM, that is, leaning for peak EGT (the fast way). The purpose of this technique is for ground leaning and takeoffs above 3000ft density altitude. NOT for climb or cruise. For climb or cruise you must lean until you feel engine roughness, then enrich just enough to achieve smooth engine operation, you are operating at a lower HP, but you will be saving both on fuel and on TBO. Mike Busch has a bunch of videos on LOP operations, he owns a Twin Cessna T310 and achieved 2x engine life versus normal TBO (and beyond). Operating LOP all the time, with the sole exception of take offs and initial climb. LOP is better, as long as the pilot is properly trained. Having engine monitoring is better, but not essential for LOP ops. You need to know the BMP (Big mixture pull). Don't leave the engine dangling in the danger zone.

Guy in red shirt will swing over to the LOP side if he watches all of Mike Busch’s Saavy videos. I believe ROP is old school, LOP is the only way to go now. Can I get an AMEN!?

The ones against running LOP are the same ones that swear by Marvel Mystery Oil. Mike Busch’s engines are 2,000 over TBO by running LOP. Watch his seminars on the subject if you want to educate yourself on the issue.

A 1/4 turn in from engine stumble on a C150 is LOP!

Red shirt hasn't the slightest idea what he's talking about... LOP is bad because you can't plan around it? That's ridiculous. I fly a PA28-180, I fly it LOP, but I plan 2+gph higher. I regularly do 3.5 hour legs landing with nearly 20 gal remaining. What issue could possibly happen that would require me to go ROP for a significant portion of my flight that wouldn't make me want to terminate the flight prematurely?

2.5 hr limit...yikes. I routinely do 5.5 hr flights in the 210 LOP

18:20 these two guys against LOP don’t know what they are talking about! The optimal timing when LOP requires MORE ignition timing! Not less.. Martin is the way smarter guys here.. those two other guys are not smart..

Red shirt lost credibility about shock cooling, shock heating is more a problem.

I'm disappointed, this was a civil discussion with good advice on both LOP and ROP operation. I wanted to see at least a couple of knocked out teeth!

On the Cirrus the reasoning for LOP is different from other planes..... remember a Cirrus “runs on a mother’s love for her only child” - Bryan with a Y........ :-)

Option 3: forget both of these and just get an engine with FADEC (ie; Rotax 912,914,etc) 🙂

Joe Johnson did my PP checkride lol. He was very intimidating but I'm glad I did it with him.

Fadec solves the problem

I'm going to go out on a limb and say that cracked cylinders are caused by excessive cylinder pressure (ie: high MP, low RPM and 75f ROP), vibration (prop not dynamically balanced, worn out engine mounts that fail to dampen vibrations) and piston slap from pistons with worn skirts. but what people don't realize is that torque is a direct measurement of cylinder pressure, how can we make the same power with lower torque? By increasing RPM, if I wanna go fast, I'll make peak continuous power by going 2500 RPM (max cont. by the book) and 28" of MP to make 75% power at peak EGT, not lean, not rich. peak...stoiciometric...the standard by which all cars use and peak EGT is also, "by the book" at 30" or less of MP. Remains to be seen if my engine will make TBO, my mechanic says I will have a cracked jug by 1200 hrs. But if mike busch has anything to say about it, I will exceed TBO by running in a way that minimizes cylinder pressure and the detonation risk, as well as making sure my oil has a good additive package to prevent corrosion and wear on extreme pressure surfaces (piston ring-cylinder wall interface, wrist pin bushings, cam lobes and lifters), by adding "asl cam guard" to a good quality oil or running something like "phillips victory" which already has high-end additive package. Personally I use phillips X/C 20w-50 + cam guard, so I have less traumatic starts in cold weather and corrosion protection for the irregular flying. The biggest thing I look forward to is GAMI's 100UL replacing 100LL, this will mean we can finally run full-synthetic oils, go longer between oil changes and massively extend engine life from the cleaner running and better oils. Lead is highly incompatible with synthetic oil, the oil won't hold it in suspension, so you get tremendous sludge that plugs up the oil passages. This is another reason I don't like ROP, it produces more soot...which equates to more sludge. I only consider ROP when I need to "damn the torpedoes, full steam ahead!" For everything except takeoff power, I'm targeting peak EGT or slightly lean of peak, even while idling on the ground.

LOP vs ROP is an infected debate. I think to understand what makes LOP a better choice is so much more than saving money on fuel, you need to read all about the 'new' facts that exist about GA piston engines. Mike Busch has a lot of interesting things to say about this and that is based on facts.

13:00 the guy in the red shirt... doesn’t seem very credible.. who would go to idle from 11000 feet, open cowl flaps, and go full rich to start down? Come on.. nobody would do that. Even the least intelligent skydive pilots keep 18 to 15 inches, close up the cowl flaps, and do appropriate mixture adjustments on the way down..

First, run your engine where you want to run it. It is your engine, your money, your airplane. In full disclosure, I run LOP. The guy in the red shirt has no clue as to what he is saying. Shock cooling has been debunked for ever. Jump planes and training airplanes go through "shock cooling" on every flight. LOP is actually LESS stressful on your engine because your internal cylinder pressure is LESS. Also, fuel is not used to cool the engine. Excess fuel is used to prevent detonation in the cylinders at max horsepower, which WILL destroy a cylinder in short order. The speed difference between my ROP and LOP speed is about 5 knots, 168 ROP vs 163 LOP. That is a 3% loss in speed. The difference in my fuel burn in 2.5GPH, 12.0GPH vs 9.5GPH. That is a 21% savings in fuel burn. So, I get there about 15 minutes later running LOP vs ROP, but have an extra 45 minutes of fuel in the tanks just in case there is some unforseen issue. I also do not plan for more than a four hour leg, with 64 gallons aboard. I can always change my destination to get more fuel as well. If you are flight planning to land with minimum fuel, maybe you need to rethink your flight planning and decision process.

"I wish pilots could have an opinion"

My first introduction to Martin was when he did easily the most complete lean of peak explanation of running at LOP and if you look at the power curve of running at LOP the power differential between LOP and ROP is minimal at best. Avweb has an excellent article regarding shock cooling at www.avweb.com/ownership/shock-cooling-time-to-kill-the-myth/. He TRIED to justify his position on shock cooling and just failed miserably because he tossed out all these excuses. As far as the flight planning for running LOP; anyone who is flight planning to use the exact amount of fuel burn to the maximum range isn’t doing a good job in the flight planning. I mean you can always do flight planning to the max demonstrated range, but why? My rule of thumb is to over-plan my fuel burn and under fly my maximum range. For instance if I’m flying an airplane that regularly burns 12gph and a max endurance of 4hrs, then plan on a 15gph fuel burn. This makes the math TONS easier because I can instantly know I’m going to need 60 gallons for that 4 hours vs. 48 gallons. Right there I’ve got a 12 gallon buffer. Another point that they very briefly touched on was the radial engine and LOP use during the war time (WWII). Lindbergh was actually in the South Pacific theater and nearly doubled the range of the fighter aircraft down there (thus credited for helping to win the war down there because it extended the range of the fighters overnight). Lindbergh knew from his trip to Paris how to really manage the fuel in his airplane and how to fly LOP. When he first shared this information with the fighter squadron he was working with (he was only supposed to be an “observer” - but that was far from the truth) the mechanics pitched a HUGE FIT over this saying it would destroy the engines. So they made a bet to see if it was damaging the engine. They let him fly one plane LOP, and when he came back, the mechanics tore the engine down and found no issues. Good discussion overall, but I think someone who is new to this conversation might be misled a bit on the shock cooling and the LOP flying.

Tripping over to dollars to pickup pennies....

The rich of peak guy is off base and is still stuck in old theories.

This video has done almost nothing other than arm pilots with false information regarding the LOP v ROP argument. Personally, either rich of peak or lean of peak are fine in reference to safe engine management. Nothing was said regarding the debris (from combustion) left in the cylinder when running ROP. Either way, your fan base should take the time to get involved with Advanced Pilot Seminars and learn, in detail, the value of LOP operations. That is not an endoresement for LOP, btw. It is simply a recommendation to learn the science behind LOP operations and the hypothetical and practical advantages of running with a cleaner engine. The GAMI folks have reams of data from their world class engine test facility. Hard to argue with the science. Whether you fly LOP or ROP, at least have the knowledge to support why you are doing what you are doing. Shock cooling your cylinders (not an issue) and worrying about fuel usage (diversion if necessary) during the flight are not reasons to not fly LOP. Please, be more educated regarding the topic before tackling. And, watch some of Martin's videos. Super bright guy with great insight and delivery

In my opinion Not worth the cost. I fly a baron at an operating cost of 400 an hour. Costs me a minimum of 10 knots and takes 2/10s an hour on typical flight. That’s 80 bucks operating cost which pays for the gas for rich of peak operation. Same math works for a bonanza.

#clickBait. 😂😂😂😂😂😂😂. How do you LOP a glider?????

Wow! The DPE is so wrong on so many levels. Uneducated and opinionated.