Commercial Pilots who don't know about piston engines
With full respect to Walter, would it not be more constructive to show Continental where their operating handbook is incorrect, rather than offering a $1000 reward to "hangar-flying-know-it-alls"? All things being equal, most pilots will gravitate to the information provided by the people that make the engine.
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The very first APS class that Andrew and I taught in was a HUGE class in Ada OK several years ago, one of the biggest ever. VIP students including senior TCM folk. They know already.
The problem is, changing a POH which is full of pearls of disaster is not something the airframe manufacturer's lawyers or anyone else wish to entertain. Mainly due to the cost, I assume.
The problem is, changing a POH which is full of pearls of disaster is not something the airframe manufacturer's lawyers or anyone else wish to entertain. Mainly due to the cost, I assume.
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extralite:
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would it not be more constructive to show Continental where their operating handbook is incorrect
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I could not agree with you more. You are exactly correct. (how come I never thought of that!!
just kidding...) We began doing that over 15 years ago. We met with a significant amount of resistance to them being willing to even look at the data. Over time, the OEMs have changed their position and are now coming around to agreeing with THEIR OWN data. (remember, "the physics are everywhere the same") One VP in a large aviation manufacturing company came to the APS class and began sending the people in his division in groups until most had taken the APS course. After trying to effect a change in the company over several years, he finally had enough and changed employment. Corporate inertia is a strong force.
Other OEMs continue to send their people to our course. We welcome them to the party. Several CASA people came to the APS class George and I taught in Sidney and there have been some changes in CASA's positions on some things. Whether or not that was a direct result of the APS class is uncertain, but the coincidence is compelling. There are many legal reasons that you will not see the POHs changed. Some new POHs are beginning to show an updated understanding.
Remember, Galileo (oops, that's a mistake, it was Bruno) was burned at the stake, but his facts remained true.
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would it not be more constructive to show Continental where their operating handbook is incorrect
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I could not agree with you more. You are exactly correct. (how come I never thought of that!!
just kidding...) We began doing that over 15 years ago. We met with a significant amount of resistance to them being willing to even look at the data. Over time, the OEMs have changed their position and are now coming around to agreeing with THEIR OWN data. (remember, "the physics are everywhere the same") One VP in a large aviation manufacturing company came to the APS class and began sending the people in his division in groups until most had taken the APS course. After trying to effect a change in the company over several years, he finally had enough and changed employment. Corporate inertia is a strong force.Other OEMs continue to send their people to our course. We welcome them to the party. Several CASA people came to the APS class George and I taught in Sidney and there have been some changes in CASA's positions on some things. Whether or not that was a direct result of the APS class is uncertain, but the coincidence is compelling. There are many legal reasons that you will not see the POHs changed. Some new POHs are beginning to show an updated understanding.
Remember, Galileo (oops, that's a mistake, it was Bruno) was burned at the stake, but his facts remained true.
Last edited by Walter Atkinson; 18th Feb 2016 at 20:23. Reason: stupid error!
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BTW, I spent dozens of hours noting the scientific errors in one company's operating manual in an attempt to get the erroneous and downright dangerous recommendations corrected. We're not talking about "opinions." We're talking about math and science inaccuracies. One would think they would have appreciated someone trying to help them not to look foolish to their customers.
It pissed them off. Twelve years later, the same errors remain.
Go figure?
What's a fella to do?
It pissed them off. Twelve years later, the same errors remain.
Go figure?
What's a fella to do?
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Ummm, Galileo was not burned at the stake. He was censured by the Church and placed under house arrest ... a fairly loose house arrest. Claiming Galileo was burned at the stake in a statement about the immutability of facts might not communicate exactly what you're trying to say, if you know what I mean.
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Brain phart on my part! You are, of course, correct. Thank you for the correction. I was thinking of Giordano Bruno and typed Galileo! Silly me. The result is still the same.
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FWIW:
Giordano Bruno, born Filippo Bruno, was an Italian Dominican friar, philosopher, mathematician, poet, and astrologer. He is celebrated for his cosmological theories, which went even further than the then novel Copernican model. He proposed that the stars were just distant suns surrounded by their own exoplanets and raised the possibility that these planets could even foster life of their own (a philosophical position known as cosmic pluralism). He also insisted that the universe is in fact infinite and could have no celestial body at its "center".
Beginning in 1593, Bruno was tried for heresy by the Roman Inquisition on charges including denial of several core Catholic doctrines (including Eternal Damnation, the Trinity, the divinity of Christ, the virginity of Mary, and Transubstantiation). Bruno's pantheism was also a matter of grave concern. The Inquisition found him guilty, and in 1600 he was burned at the stake in Rome's Campo de' Fiori.
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FWIW:
Giordano Bruno, born Filippo Bruno, was an Italian Dominican friar, philosopher, mathematician, poet, and astrologer. He is celebrated for his cosmological theories, which went even further than the then novel Copernican model. He proposed that the stars were just distant suns surrounded by their own exoplanets and raised the possibility that these planets could even foster life of their own (a philosophical position known as cosmic pluralism). He also insisted that the universe is in fact infinite and could have no celestial body at its "center".
Beginning in 1593, Bruno was tried for heresy by the Roman Inquisition on charges including denial of several core Catholic doctrines (including Eternal Damnation, the Trinity, the divinity of Christ, the virginity of Mary, and Transubstantiation). Bruno's pantheism was also a matter of grave concern. The Inquisition found him guilty, and in 1600 he was burned at the stake in Rome's Campo de' Fiori.
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Walter, thank you for the reply but I still have some questions:
Yes but do you believe it is safe to run LOP without any limits to power and without instrumentation? You said yes to that but then went on to specify two instruments that are required.
That is not the method jabawocky described. He didn't mention the use of carb heat or EGT gauge. But anyway I can see that carb heat would aid vaporisation. At the same time it seems to me that with a little bit of carb heat it would be a marginal gain as the fuel doesn't all vaporise at the same temp. But I've never tried this so I would like to see the data.
How do you know you have the lowest DIFF when using only single EGT? Applying carb heat will enrich the mixture. How can you be sure that the smooth running is a result of balanced flow rather than the enrichment, if you only have single point EGT and the feeling in your butt? After all, if I lean until the engine runs rough and then add back some fuel it will smooth out but I haven't balanced the fuel flow by doing that. If I apply carb heat I can get the same result. So how do I know the mixture is balanced?
Carbed engines have notoriously poor F:A ratios and as a result many think it impossible to run them LOP
(I taught my Aussie colleague!)....The key is finding the optimal IAT using carb heat to get the fuel which has been atomized to become vaporized (I am hesitant to spend hours typing what can be demonstrated in under a minute in the airplane). Once this happens, the F:A ratios will be well balanced.
If you have a conformity problem LOP, the engine will let you know by running rough. Not so if ROP....Use the minimal carb heat to get the lowest DIFF number and you're good to go...It only requires a single-probe EGT and a carb temp gauge.
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Yes but do you believe it is safe to run LOP without any limits to power and without instrumentation? You said yes to that but then went on to specify two instruments that are required.
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It's less of a problem than running ROP without regard to power or instrumentation. We haven't seemed to mind doing that.
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That is not the method jabawocky described. He didn't mention the use of carb heat or EGT gauge. But anyway I can see that carb heat would aid vaporisation. At the same time it seems to me that with a little bit of carb heat it would be a marginal gain as the fuel doesn't all vaporise at the same temp. But I've never tried this so I would like to see the data.
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Well, I think he was talking about injected engines, and he didn't go into details, but I know that he knows. You do need some method to know where the mixture is set whether ROP or LOP. Why do we accept not knowing where the mixture is set when ROP and have a fit if we don't know it LOP? That's backwards. It's much more dangerous not knowing ROP, it's just that we've become comfortable not knowing because we didn't know what we didn't know.
The data will be compelling for you to observe.
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How do you know you have the lowest DIFF when using only single EGT? Applying carb heat will enrich the mixture. How can you be sure that the smooth running is a result of balanced flow rather than the enrichment, if you only have single point EGT and the feeling in your butt? After all, if I lean until the engine runs rough and then add back some fuel it will smooth out but I haven't balanced the fuel flow by doing that. If I apply carb heat I can get the same result. So how do I know the mixture is balanced?
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When one leans to roughness and enriches to smoothness one has NO idea where the mixture is set. It could be well ROP or well LOP or anywhere in between, depending on the balance of the F:A ratios. If one leans to roughness, then adds a bit of carb heat, the major effect is to vaporize the fuel, not richen the mixture, although both are happening. From that point do it again, and again, until no more carb heat smooths things out. That is where you will have balanced F:A ratios. This is crude without instrumentation and unless one has a very good handle on how this all works, may be difficult to achieve on the first effort. Instrumentation, even minimal, is a huge asset. One "can" fly needle, ball, and airspeed in instrument conditions, but having an AI, Altimeter, and DG is a BIG help! If you have a carb temp gauge (you do have one, don't you?) once you find the optimal temp, it works under all conditions.
This is one hell of a lot easier to demonstrate than type.
Yes but do you believe it is safe to run LOP without any limits to power and without instrumentation? You said yes to that but then went on to specify two instruments that are required.
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It's less of a problem than running ROP without regard to power or instrumentation. We haven't seemed to mind doing that.
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That is not the method jabawocky described. He didn't mention the use of carb heat or EGT gauge. But anyway I can see that carb heat would aid vaporisation. At the same time it seems to me that with a little bit of carb heat it would be a marginal gain as the fuel doesn't all vaporise at the same temp. But I've never tried this so I would like to see the data.
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Well, I think he was talking about injected engines, and he didn't go into details, but I know that he knows. You do need some method to know where the mixture is set whether ROP or LOP. Why do we accept not knowing where the mixture is set when ROP and have a fit if we don't know it LOP? That's backwards. It's much more dangerous not knowing ROP, it's just that we've become comfortable not knowing because we didn't know what we didn't know.
The data will be compelling for you to observe.
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How do you know you have the lowest DIFF when using only single EGT? Applying carb heat will enrich the mixture. How can you be sure that the smooth running is a result of balanced flow rather than the enrichment, if you only have single point EGT and the feeling in your butt? After all, if I lean until the engine runs rough and then add back some fuel it will smooth out but I haven't balanced the fuel flow by doing that. If I apply carb heat I can get the same result. So how do I know the mixture is balanced?
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When one leans to roughness and enriches to smoothness one has NO idea where the mixture is set. It could be well ROP or well LOP or anywhere in between, depending on the balance of the F:A ratios. If one leans to roughness, then adds a bit of carb heat, the major effect is to vaporize the fuel, not richen the mixture, although both are happening. From that point do it again, and again, until no more carb heat smooths things out. That is where you will have balanced F:A ratios. This is crude without instrumentation and unless one has a very good handle on how this all works, may be difficult to achieve on the first effort. Instrumentation, even minimal, is a huge asset. One "can" fly needle, ball, and airspeed in instrument conditions, but having an AI, Altimeter, and DG is a BIG help! If you have a carb temp gauge (you do have one, don't you?) once you find the optimal temp, it works under all conditions.
This is one hell of a lot easier to demonstrate than type.
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I'd hazard a guess. The engine will run smoothest at the lowest DIFF at LOP.
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Correct, and this is usually with a minimal degree of carb heat unless it is a very, low OAT. Additional carb heat from that point does not improve F:A balance and will reduce power.
Use the least carb heat required to get the lowest DIFF number. Once you find that carb temp, it works at all OATs.
I've accomplished this in numerous, different types of carbureted aircraft and it has worked in every, single one of them. I guess Sir Isaac Newton was right. "The physics are everywhere the same."
I'd hazard a guess. The engine will run smoothest at the lowest DIFF at LOP.
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Correct, and this is usually with a minimal degree of carb heat unless it is a very, low OAT. Additional carb heat from that point does not improve F:A balance and will reduce power.
Use the least carb heat required to get the lowest DIFF number. Once you find that carb temp, it works at all OATs.
I've accomplished this in numerous, different types of carbureted aircraft and it has worked in every, single one of them. I guess Sir Isaac Newton was right. "The physics are everywhere the same."
Thanks for the reply Walter.
Il be trying the LOP. Assuming we go 50 degrees LOP for the hottest cylinder, what would we expect the CHT to do? Intuitively i feel like it would heat up as we leaned off, but from this discussion it seems like it might also cool a little?
Il be trying the LOP. Assuming we go 50 degrees LOP for the hottest cylinder, what would we expect the CHT to do? Intuitively i feel like it would heat up as we leaned off, but from this discussion it seems like it might also cool a little?
The curves that Jabba posts (which were produced by APS) provide the answer.
The CHT will be cooler at any mixture richer or leaner than around 50 degrees F rich of peak.
To put this another way, your CHT will be hottest at an EGT of around 50 degrees F rich of peak, and will get cooler whichever way you change the mixture.
It's counter intuitive, but your CHT will be cooler at peak EGT than at 50 degrees F rich of peak. Keep leaning from peak EGT and you're going LOP and the CHT is getting even cooler.
That's why the APS folks say that when running ROP, it's important to make sure the mixture is set far enough ROP.
The CHT will be cooler at any mixture richer or leaner than around 50 degrees F rich of peak.
To put this another way, your CHT will be hottest at an EGT of around 50 degrees F rich of peak, and will get cooler whichever way you change the mixture.
It's counter intuitive, but your CHT will be cooler at peak EGT than at 50 degrees F rich of peak. Keep leaning from peak EGT and you're going LOP and the CHT is getting even cooler.
That's why the APS folks say that when running ROP, it's important to make sure the mixture is set far enough ROP.
Perhaps the reluctance to run lean is from what we have all learned from early on about engine. Running lean can cause knocking..pre-detonation and damage to valves.
How are leaded aero engines immune to this?
How are leaded aero engines immune to this?
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Perhaps the reluctance to run lean is from what we have all learned from early on about engine.
Running lean when ROP(Not LOP)can cause knocking..
1. On a conforming NA engine on conforming fuel, detonation is not possible.
2. On a turbo charged engine it is possible by misuse of the mixture knob to cause detonation, but only on the rich side of peak.
3. Detonation is what people call knock, but you can't hear it in a plane like you can a car.
4. Pre-ignition, usually (by far the most) caused by a spark plug ceramic being damaged. Occasionally by cross firing in magnetos and possible but rare by helical tangs being screwed in too far and exposed from the head. This damages pistons and really fast.
4(a) Spark plugs get damaged mostly by being dropped by mechanics. Some times but not often as a result of detonation shock waves.
5. Valve damage is hardly unlikely caused by detonation or even preignition. Burned valves are caused by machining errors at time of installation, the defects take time to appear, usually 600 hours +600/-200 and any mixture abuse is likely to speed up the process due heat and pressure, but the defect is there from the start and not pilot induced.
How are leaded aero engines immune to this?
Maybe ask your question again in a different way?Hope that helps.
Pb Ballon
Whoever you are, I feel like you have been a good student of the science.
What does "running lean" mean? All mixtures that support combustion are somewhere on the lean curve.
And wouldn't the greatest risk of all those nasties (noting that pre-ignition and detonation are different things) be at the mixture setting that produces the greatest cylinder peak pressure and temperature? i.e at around 50 degrees F rich of peak?
When an engine starts running 'rough' when leaned, it is almost always because of the imbalance in F/A ratios going to each cylinder and the resultant imbalance in the power outputs of each cylinder. Nothing is 'misfiring' or detonating or pre-igniting or knocking.
And wouldn't the greatest risk of all those nasties (noting that pre-ignition and detonation are different things) be at the mixture setting that produces the greatest cylinder peak pressure and temperature? i.e at around 50 degrees F rich of peak?
When an engine starts running 'rough' when leaned, it is almost always because of the imbalance in F/A ratios going to each cylinder and the resultant imbalance in the power outputs of each cylinder. Nothing is 'misfiring' or detonating or pre-igniting or knocking.
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oggers
Sorry if I have confused you but I do not know what you are referring to?
I suspect it is where I was talking about an engine I know has no leaks, good induction and a carburettor…….and it nicely runs LOP? If that is the one it is an O320 powered RV6 with a FP prop, and it does have a single point EGT (which is almost useless by itself) but I know it runs nicely LOP, and the simple method is to lean for a 100 RPM drop. This is about 10-11% drop in power, or like the old days a 10% BMEP drop.
Let me know if that is not what you were thinking of. Happy to help explain otherwise. Or Walter will if I am not doing a good job of it.
Not everyone will be as confident or have the understanding and feel for this, but many of the APS students will. Why is that you might be thinking?
The answer is what they see in the cockpit using whatever instrumentation they have, complete or very little, they can interoperate that info to reflect what they would have seen in class on a fully instrumented dyno. The human FADEC is a pretty powerful thing.
That is not the method jabawocky described. He didn't mention the use of carb heat or EGT gauge.
I suspect it is where I was talking about an engine I know has no leaks, good induction and a carburettor…….and it nicely runs LOP? If that is the one it is an O320 powered RV6 with a FP prop, and it does have a single point EGT (which is almost useless by itself) but I know it runs nicely LOP, and the simple method is to lean for a 100 RPM drop. This is about 10-11% drop in power, or like the old days a 10% BMEP drop.
Let me know if that is not what you were thinking of. Happy to help explain otherwise. Or Walter will if I am not doing a good job of it.
Not everyone will be as confident or have the understanding and feel for this, but many of the APS students will. Why is that you might be thinking?
The answer is what they see in the cockpit using whatever instrumentation they have, complete or very little, they can interoperate that info to reflect what they would have seen in class on a fully instrumented dyno. The human FADEC is a pretty powerful thing.
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Sorry if I have confused you but I do not know what you are referring to?
The key is finding the optimal IAT using carb heat to get the fuel which has been atomized to become vaporized...Non-conforming engines will "seem" to run smoothly ROP...Your Mark One calibrated butt doesn't feel the differences when ROP. It does when LOP.
Also:
the simple method is to lean for a 100 RPM drop...Not everyone will be as confident or have the understanding and feel for this, but many of the APS students will. Why is that you might be thinking?
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Walter:
The question was do you think it safe to run LOP without limitation to power. I don't agree that we 'haven't minded running ROP at full power'. The manufacturers have given us limtations for both LOP and ROP best power mixture. So we have minded. What we haven't minded is running full rich.
He specifically said "the Big Mixture Pull works every time. And yes that is a carby engine. "
No doubt. Please post this data for the carby engine.
Yes I get the concept. But it depends on how much fuel you actually vaporise versus how much heat you have to use. The data will clear this up I'm sure....
[LOP is] less of a problem than running ROP without regard to power or instrumentation. We haven't seemed to mind doing that.
Well, I think he was talking about injected engines,
The data will be compelling for you to observe.
If one leans to roughness, then adds a bit of carb heat, the major effect is to vaporize the fuel, not richen the mixture, although both are happening. From that point do it again, and again, until no more carb heat smooths things out. That is where you will have balanced F:A ratios.
This is why there is a 2.5 day face-to-face course.
Reacting to ad hoc questions on a blog is not an efficient or effective way to teach people engine management. It is also unreasonable to expect someone to divert their personal time to answering every supplementary question that will almost invariably arise from a narrow explanation of the issues relevant to a specific set of circumstances.
If you think you're being scammed, oggers, just move on. Leave the credulous to the snake oil salesmen.
If you don't think you're being scammed, perhaps you should ask yourself whether it's reasonable to demand that you be given, free of charge, a complete, comprehensive, written answer, covering all the 'ifs' and 'buts' and exceptions, to every question you're inclined to ask.
Your closing sentence smells sarcastic and suggests feigned confusion.
The voluntary contributions of the APS folks on blogs often remind me of the old saying: "No kind act goes unpunished."
Reacting to ad hoc questions on a blog is not an efficient or effective way to teach people engine management. It is also unreasonable to expect someone to divert their personal time to answering every supplementary question that will almost invariably arise from a narrow explanation of the issues relevant to a specific set of circumstances.
If you think you're being scammed, oggers, just move on. Leave the credulous to the snake oil salesmen.
If you don't think you're being scammed, perhaps you should ask yourself whether it's reasonable to demand that you be given, free of charge, a complete, comprehensive, written answer, covering all the 'ifs' and 'buts' and exceptions, to every question you're inclined to ask.
Your closing sentence smells sarcastic and suggests feigned confusion.
The voluntary contributions of the APS folks on blogs often remind me of the old saying: "No kind act goes unpunished."
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Pb Ballon is correct
oggers, let me answer each one at a time.
1.The particular aircraft RV6/O320 I referred to is a conforming engine sans carbie heat. Don't know why and don't care either. On the odd occasion I crack the throttle off the WOT position, another technique that helps in some aircraft because it makes some turbulent flow. Non of what I said is contradicting what Walter said, some times you get lucky and some times you have to deploy all the tricks in the book. There is a PA24 in my hangar that has a multitude of issues of which I am working through, but so far the F/A ratio's are so poor even running full rich it is a nightmare. Yet the LAME's and engine builder have their head in the sand on it. I will win eventually even if all we do is get the ROP side of things wring right. There is no one size fits all with carby engines I am afraid.
2. I think you will find Walter was referring to the EMS visual verification by reference to the EGT values, it is fair to assume the slow leaning process used here will not yield any perceivable deceleration at all. If however a BMP is the way you do it, you will feel the deceleration and not see the EMS trends because it is done quickly. (You really do need to spend a weekend in class, Ada OK in a couple of weeks is your next chance).
3. Answres in red here;
Detail on starting at 100% power and going LOP. Simply put when you do a BMP at any power setting you end up on the graph at the point around the most efficient or where best 1/BSFC peaks. So at 100%, scooting down the beach having a ball……the BMP achieves what the old radial airliners did with a 10% BMEP drop, if that is done in my aircraft with a CSU its stays at 2700, if its a FP it drops around 100 RPM, and you get around 88% power typically because unless the QNH is really high you never had 100% anyway even with the wheels in the water 
At high powers you want to be around 80dF LOP (70-90 range these are rubbery figures and we do not split atoms here), and that will coincide with about the 10% or so power drop.
There is no problem doing this at all. None, Zip,Zilch….and the engine will run for thousands of hours like this happily. This is how your diesels and turbines run so why not your IO540. The CHTs will be 30-40dF lower and this confirms the ICP is lower than when full rich, what is not to like.
I don't have a 10' 2700 RPM photo, because that would be illegal here (wish I did) but I have done LOP take-offs at around 91% power, and the take off run for my plane becomes like a Bonanza, almost exactly and the CHT's are unbelievable good. Most GA planes need the extra ponies so it is not suggested for everyone else. But it proves the point well. What I do have is an old photo from when "morno" was flying and this is 1000' and 2400 RPM, and the power was about 80%. Enjoy!
Here is one in the cruise at 10,000' (new panel)
And here is the concept graph, derived from real data, and all the answers to your questions can be found here. The two brown 1/BSFC curves represent a moderately high power, say 80-85% for the unbroken line and about 70-75% for the broken brown line. As the %age power reduces that brown line peaks a little further to the right. If it were 65% power or less it would peak in the -10 to -20 from peak region.
If you want to see all the data…and there is tonnes of it, you need to either be in Ada OK in a few weeks, BNE Qld next year, or do the online class (good but no Q&A sessions with that!). Beyond that I think we have exhausted the forum concept.
If anyone else has questions please fire away.
The voluntary contributions of the APS folks on blogs often remind me of the old saying: "No kind act goes unpunished."
oggers, let me answer each one at a time.
1.The particular aircraft RV6/O320 I referred to is a conforming engine sans carbie heat. Don't know why and don't care either. On the odd occasion I crack the throttle off the WOT position, another technique that helps in some aircraft because it makes some turbulent flow. Non of what I said is contradicting what Walter said, some times you get lucky and some times you have to deploy all the tricks in the book. There is a PA24 in my hangar that has a multitude of issues of which I am working through, but so far the F/A ratio's are so poor even running full rich it is a nightmare. Yet the LAME's and engine builder have their head in the sand on it. I will win eventually even if all we do is get the ROP side of things wring right. There is no one size fits all with carby engines I am afraid.
2. I think you will find Walter was referring to the EMS visual verification by reference to the EGT values, it is fair to assume the slow leaning process used here will not yield any perceivable deceleration at all. If however a BMP is the way you do it, you will feel the deceleration and not see the EMS trends because it is done quickly. (You really do need to spend a weekend in class, Ada OK in a couple of weeks is your next chance).
3. Answres in red here;
I don't think that leaning until you get a 100rpm drop is too difficult for the average pilot. No it is not, but with a C/S prop it is so it is not a one size fits all deal hereDoing that from 100% power is the concern especially as Walter is now doing that with carb heat applied.Here again you show the need to do the course and understand the science. I will explain below but read Lead Ballons opening line about how easy it is to teach on a forum. I would like to see your data for doing this with a carb engine. Simply describing the priocess raises more questions than it answers. This is why we take hours of questions at breaks, lunch breaks, over dinner during a class weekend. If you do not understand from the class we try to explain it better for you during the break.
Simply put when you do a BMP at any power setting you end up on the graph at the point around the most efficient or where best 1/BSFC peaks. So at 100%, scooting down the beach having a ball……the BMP achieves what the old radial airliners did with a 10% BMEP drop, if that is done in my aircraft with a CSU its stays at 2700, if its a FP it drops around 100 RPM, and you get around 88% power typically because unless the QNH is really high you never had 100% anyway even with the wheels in the water At high powers you want to be around 80dF LOP (70-90 range these are rubbery figures and we do not split atoms here), and that will coincide with about the 10% or so power drop.
There is no problem doing this at all. None, Zip,Zilch….and the engine will run for thousands of hours like this happily. This is how your diesels and turbines run so why not your IO540. The CHTs will be 30-40dF lower and this confirms the ICP is lower than when full rich, what is not to like.
I don't have a 10' 2700 RPM photo, because that would be illegal here (wish I did) but I have done LOP take-offs at around 91% power, and the take off run for my plane becomes like a Bonanza, almost exactly and the CHT's are unbelievable good. Most GA planes need the extra ponies so it is not suggested for everyone else. But it proves the point well. What I do have is an old photo from when "morno" was flying and this is 1000' and 2400 RPM, and the power was about 80%. Enjoy!
Here is one in the cruise at 10,000' (new panel)
And here is the concept graph, derived from real data, and all the answers to your questions can be found here. The two brown 1/BSFC curves represent a moderately high power, say 80-85% for the unbroken line and about 70-75% for the broken brown line. As the %age power reduces that brown line peaks a little further to the right. If it were 65% power or less it would peak in the -10 to -20 from peak region.
If you want to see all the data…and there is tonnes of it, you need to either be in Ada OK in a few weeks, BNE Qld next year, or do the online class (good but no Q&A sessions with that!). Beyond that I think we have exhausted the forum concept.
If anyone else has questions please fire away.