LOP vs ROP Smackdown - InTheHangar Ep 112

If you've bought a teeshirt-- do you think the higher quality Comfort Colors is worth the hassle?

[gregdavis]

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.

[GeezerGeekPilot]

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

[Jason-izob]

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

[martinpauly]

Wow, we look SERIOUS in that thumbnail image! 😁

[GeezerGeekPilot]

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

[dtwwtd]

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.

[buckshot]

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 🇺🇸✈️

[upsidedowndog]

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.

[zafa_]

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

[LeviNoguess]

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

[almarasco]

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.

[Hedgeflexlfz]

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.

[bernarddugas]

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

[swimbikeruntoday]

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

[ShuRugal]

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.

[ronnieeubanks]

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

[logannielsen]

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

[deani]

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.

[billmoran]

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

[williamfahle]

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.