ROP versus LOP and the Lycoming IO-360

[Bob_Belville]

How true, Bob. Corrosion is what kills these lycs. more than anything. Swallowing valves usually happens as an effect of running to high of CHT and coking the little fellers, which can be an effect of running the thing about 50 ROP and/or not getting enough oil down those pushrod tubes to the valves.

Have you decided on Ney nozzels or Centrilube or stock with the weird new lifters yet?

Mike, I went with what Tim Hess recommended - stock cam and Superior conventional lifter. Options would have meant more delays. We ran into a hitch last week, a couple of the the lifter bores turned out to be something like 0.005 over so Tim is sleeving and boring.With set up it's going to be next week before the engine is ready. Looks like the week after Xmas now.

[pinerunner]

Wouldn't this "3-4 knots" depend on how much LOP a person chose to run though?  10 LOP vs 50 LOP can make quite a difference...right?

Yep. On the LOP side power is proportional to fuel flow (14.9 HP/GPH has been quoted and seems to work well for me) (as long as its still running of course) so going further LOP will drop power.

[jetdriven]

Wouldn't this "3-4 knots" depend on how much LOP a person chose to run though?  10 LOP vs 50 LOP can make quite a difference...right?

Yes it does. Anything leaner than about 25 Lop at 65% or ~40 lop at 75% is slower for a given fuel flow, and less efficient.

[David Brown]

Because we don't have ICP gauges in the cockpit, we need to use another measure to determine these values. CHT is directly proportional to ICP. If the CHTs are under control, that means that the cylinders are producing acceptable ICPs as well. When it comes to ICP, CHT is the only issue.

 

I have been reading the first page so far and there has been some of this Mike Busch talk about using 380dF CHT as a target CHT. I noted one post where it was stated that the CHT is only part of the equation.

 

Let me debunk this myth right here and now. You can run an engine with high, very high and damagingly high ICP's and have cool enough CHT's if you have the cooling available. The cooler head does nothing for the piston, con rods bearings etc. but the CHT is cool.

 

So it is not wise to just assume that CHT is the measure. Where I come from it is probably OK, it never gets cold enough, but winter and cold dense air can give you the ability to run right in the APS red box, and not exceed 380dF CHT.

 

Mike writes lots of good things but his view of the world about 380dF being like some sort of target is plain wrong. End of arguments

 

So to whoever the poster is DS1980, can I suggest you rethink the last 5 words above. Please.

[David Brown]

Ok, so here is the question that always makes me ponder the why-go-LOP question:

1. Is it just about savings?  How much fuel does one feel they save per flight hour and at what cost ... slower cruise speed = putting more time on their engine and you get to sit there longer?  
2. Does one really believe that they have a better chance of reaching TBO by going LOP?  
3. Is the engine being better cared for enroute?   CHT/EGT within limits is CHT/EGT within limits.                   
4. Is not the Mooney the best in the market at providing speed AND efficiency at the same time -- we all know it is.  So, what am I missing...why LOP?

Please help me "see the light" because my current way of thinking is such that 9.5 gph at 157ktas is hard to improve upon -- what would LOP do for me?  Save me less than 1 gph and slow me down by 10-15 knots?  I bought my Mooney so I could go fast -- why slow down to p-b-c speeds for a measly 1/2 gal or so savings per hour?

 

If I was feeding a big fuel-guzzling 6-cylinder, then LOP would make more sense to me, but, for us Lyc IO-360 operators, that is not the choice we made.

 

Without fail, every trip we take, the shorter the ETE, the bigger my wife's smile...

 

Why does 2/3 of our group (estimated) fly LOP?

 

1. Depending on the power you want to use, the fuel flow to have the same ICP's can be up to 50% higher to get the appropriate ROP setting compared to a LOP setting. It is often 25-30% higher. The speed loss is 3-6 knots maximum and that often represents less than 5% so the Miles per Gallon and even the hours on the engine are a long way in front.

The point here is you need to set the efficient LOP setting properly otherwise as I suspect many people do they end up too far LOP and end up on the back end of the BSFC curve.

 

2. Lower ICP, Lower CHT, Less crud on the pistons valves and less crud exposure to exhaust valve guides, Vs the opposite, tends to suggest you have a far better chance. of getting to TBO or further. Experience showed on the old R3350's in military use that TBO was around 700 hours, when run ROP, the airlines who ran hundreds of millions of hours LOP on the same engines achieved 3600 hours TBO. American 400,000,000 hours is a pretty good survey.

 

3. YES!!! CHT limits are a certification limit, and the strength of aluminium with increased temperature drops rapidly, add to that higher pressures and forces. EGT limits? There are none really, except for TIT but that is for a different reason.

 

4. I am not buying into a brand/vaue war, I bet my aircraft trumps your Mooney but is that fair? The point is your efficient airframe Mooney can run at its most efficient if you do several things, keep the airframe in good order, fly it efficiently and manage the engine efficiently. The best engine efficiency is at the best BSFC, simple as that. Work that out and use it. Oddly enough it will always be a LOP power setting. Ever wondered about all these diesel cars? The next thing is IAS, so you want the best L/D for your mooney? well set the best L/D and then set the best BSFC that achieves that and now you have the best MPG you can. but it will be C172 speed or less.

 

WOT/2400-2500RPM/10-20dF LOP at higher cruise levels is the optimal setting, and down lower at higher MP a bit more LOP up to about 80dF at floe to sea level. Study these curves below.

http://i849.photobucket.com/albums/ab58/jaba430/Landmarksgraph_zpsbfb07cbb.gif

 

I suggest you learn how this word properly, it will save you a fortune. I would also suggest you learn how better to know what your EMS is telling you. Enrol in the next APS class, and if you feel you did not get value for it, John Deakin will write you a cheque!.

[David Brown]

 

A dumb question here, but would someone care to expound on the details of the Red Box ....specifically, for 65%, is 100ºF-ROP-to-Peak the area to avoid or is this the recommended area to operate?

 

Red Box = No Fly Zone 

 At and below about 60% power, there is no red box. Put the mixture wherever you want it. 

 At about 65% power or so, 100ºF ROP to Peak. 

 At about 70%, 125ºF ROP to 25ºF LOP. 

 At about 75%, 180ºF ROP to 40ºF LOP. 

At about 80%, 200ºF ROP to 60ºF LOP. 

 

 

It is the area to avoid. Take a look at this interactive from the APS website.

http://www.advancedpilot.com/redbox.html

 

Play with the power knob on the bottom tool.

[AndyFromCB]

It is the area to avoid. Take a look at this interactive from the APS website.

http://www.advancedpilot.com/redbox.html

 

Play with the power knob on the bottom tool.

 

Oh my Lord, I've run my arrow in the red box the entire time I've owned it (wide open throttle, 2500rpm), peak EGT. It had 1550 hours on a 1400 hour engine before I sold it and zero engine related maintenance costs. My Bravo has run 1600 hours on the last engine, always about 75-100 (depending on OAT/CHT) rich of peak according to prior owner and it wasn't the cylinders that finally grounded the aircraft, it was the usual camshaft issues.

 

I completely agree that ICPs are highest right at 50ROP. I completely disagree that it makes a damn bit of a difference on my intercooled engine. If I was to run my Bravo 200 rich of peak, I'd be putting 25gph thru that engine at 75%. 

[WardHolbrook]

Seriously, does anyone still have misgivings about LOP operations? That's so 2008. 

[David Brown]

Oh my Lord, I've run my arrow in the red box the entire time I've owned it (wide open throttle, 2500rpm), peak EGT. It had 1550 hours on a 1400 hour engine before I sold it and zero engine related maintenance costs. My Bravo has run 1600 hours on the last engine, always about 75-100 (depending on OAT/CHT) rich of peak according to prior owner and it wasn't the cylinders that finally grounded the aircraft, it was the usual camshaft issues.

 

I completely agree that ICPs are highest right at 50ROP. I completely disagree that it makes a damn bit of a difference on my intercooled engine. If I was to run my Bravo 200 rich of peak, I'd be putting 25gph thru that engine at 75%. 

 

So in your opinion the intercooler makes the difference? 

 

We at APS do not offer opinions, just data and our commentary is based on that data. I would invite you to go study the data. 75% power at peak EGT is probably not going to crater your engine and you may well get a good Lycoming to do that. There is a lot of conservatism built into them but even the designer would argue about operating the engine at certain ICP's & CHT's. The airframe marketing folk do not seem to have the same goals.

 

For a 270HP engine at 75% power or about 200ish HP 25GPH would be way more than 200dF ROP. I have a feeling if what you are thinking is that setting, you are not actually sure of hat peak actually is on the day.

 

I suspect you are much further from peak than the 100dF in which case it is no wonder you observe good results.

 

Ward that is 

[DS1980]

I have been reading the first page so far and there has been some of this Mike Busch talk about using 380dF CHT as a target CHT. I noted one post where it was stated that the CHT is only part of the equation.

 

Let me debunk this myth right here and now. You can run an engine with high, very high and damagingly high ICP's and have cool enough CHT's if you have the cooling available. The cooler head does nothing for the piston, con rods bearings etc. but the CHT is cool.

 

So it is not wise to just assume that CHT is the measure. Where I come from it is probably OK, it never gets cold enough, but winter and cold dense air can give you the ability to run right in the APS red box, and not exceed 380dF CHT.

 

Mike writes lots of good things but his view of the world about 380dF being like some sort of target is plain wrong. End of arguments

 

So to whoever the poster is DS1980, can I suggest you rethink the last 5 words above. Please.

 

Read post #44, and stop hiding behind the APS facade.

 

380 degree CHT is a function of metallurgy, and it is not wrong. How many hours does Busch have on his cylinders? 210% of TBO. If this was his bottom end it would be impressive. But for cylinders to have 4500 hours on them is remarkable. The reason we have something called "TOH" is because of rust and heat. If these are eliminated, then we replace them due to fatigue. It will be interesting to see how far he can take his cylinders.

 

Don't come here with your attitude. I go out of my way to be helpful and courteous. I will make an exception for you. There are many on here that make you look like amateur hour.

[Steve Dawson]

_Interesting,

[DS1980]

Indeed. There is more to engine operation than a course. Someone that  says "end of argument" has no argument. 380 degrees wasn't just pulled out of air. Saying that a pioneer of this stuff is just plain wrong is a level of incompetence I will not tolerate. We have many people reading these threads that don't participate because they are either here as a guest or learning. We cannot have people giving out wrong information, as there may be an impressionable pilot here that heeds bad advise.

[Cruiser]

Quote: David Brown, on 21 Dec 2013 - 06:48 AM, said: snip....... Mike writes lots of good things but his view of the world about 380dF being like some sort of target is plain wrong. End of arguments  So to whoever the poster is DS1980, can I suggest you rethink the last 5 words above. Please.

 

Quote: DS1980 , on 21 Dec 2013 - 07:16 AM, said: snip....... Don't come here with your attitude. I go out of my way to be helpful and courteous. I will make an exception for you. There are many on here that make you look like amateur hour.

 

Darin, Happy Birthday yesterday. I hope you had a great one!

A little harsh, perhaps?

[DS1980]

Cruiser,

Thanks my man, hope all is well on your end.

Perhaps a little, but justifiable. We cannot be giving opinions about these things when there is repeatable evidence to the contrary.

 

Plus I just had hernia surgery and am a little high on Hydrocodone. Might be a factor as well. Thank goodness for narcotic grade pain killers. 

[larryb]

I welcome David's posts. They are the only folks with real instrumented data.

Sent from my iPad using Tapatalk

[DS1980]

There are plenty of people who collect this type of data, just not for a profit.

[Steve Dawson]

Indeed. There is more to engine operation than a course. Someone that  says "end of argument" has no argument. 380 degrees wasn't just pulled out of air. Saying that a pioneer of this stuff is just plain wrong is a level of incompetence I will not tolerate. We have many people reading these threads that don't participate because they are either here as a guest or learning. We cannot have people giving out wrong information, as there may be an impressionable pilot here that heeds bad advise.

We're very thankful you're here for us.

What's your real name by the way?

[DS1980]

I wasn't implying I know everything or am a subject expert, but do know enough to offer help. I just want folks to know there is something to the 380 degree CHT.

 

It's Darin, as stated on my signature line.

[Hondo]

John Deakin's response to Lycoming statements about LOP operation.  

 

http://www.advancedpilot.com/articles.php?action=article&articleid=1838

[mcpilot]

John Deakin's response to Lycoming statements about LOP operation.

http://www.advancedpilot.com/articles.php?action=article&articleid=1838

In this article Deakin mentions advancing the throttle to regain the power and that this will increase fuel flow to maintain mixture. Is this what you all get from this? I was under the assumption that advancing the throttle would progressively cause a leaning of the mixture....

[Cruiser]

You have to be careful in reading some of these articles because there are many different engine/plane combinations and a "one size fits all" does NOT apply.

The biggest difference is turbo vs normally aspirated (NA).

Next is the carburetor vs injected engine. Some but not all carburetors can run smoothly LOP.

Next is the pressurized vs non pressurized mags

The (NA) group normally operate at WOT to begin with so there is no "advancing the throttle" since it is already at the stop.

I think the comment above applies to turbocharged engines or very low altitudes in NA engines when the pilot does not use WOT.

[Super Dave]

In this article Deakin mentions advancing the throttle to regain the power and that this will increase fuel flow to maintain mixture. Is this what you all get from this? I was under the assumption that advancing the throttle would progressively cause a leaning of the mixture....

Although not stated explicitly, my interpretation is that he is referring to turbo charged engines in that part of the article. Lycoming's concern is that adding MP back while LOP will enrichen things to an undesirable mixture. I think what Deakin is saying is that at cruise settings, this is not the case.

[David Brown]

Correct, and once more Lycoming are talking rubbish.

 

I am just about to jump in a Piper Matrix with a past student to do exactly that procedure. 

 

 

PS: We survived and it worked really well. 

[David Brown]

Read post #44, and stop hiding behind the APS facade.

 

380 degree CHT is a function of metallurgy, and it is not wrong. How many hours does Busch have on his cylinders? 210% of TBO. If this was his bottom end it would be impressive. But for cylinders to have 4500 hours on them is remarkable. The reason we have something called "TOH" is because of rust and heat. If these are eliminated, then we replace them due to fatigue. It will be interesting to see how far he can take his cylinders.

 

Don't come here with your attitude. I go out of my way to be helpful and courteous. I will make an exception for you. There are many on here that make you look like amateur hour.

 

Darin,

Sorry to hear you have been in for surgery, that must be no fun at this time of year. I trust you are on the mend soon.

 

My apologies for not seeing post #44, I am glad to see you were correcting the earlier post somewhat. My recent joining of Mooneyspace has meant getting used to a completely new forum format to others I am familiar with and I think I did not realise there was additional posts, or perhaps I scrolled past that and other close by somehow as I had not seen that one.

 

You are quite correct in saying that the APS recommended 380dF limit for CHT is a function of metallurgy however it is only part of the story as you agreed to in post #44. You can heat an aluminium cylinder head and steel cylinder assembly and aluminium piston to well beyond 500dF and leave it there all year if you like, and provided you do not subject it to 20 or so 1000PSI cycles every second, it will cool down and remain its strength quite happily back at normal temperatures.

 

At 380dF the A242-T571(AMS4220) Aluminium is at 78% of its yield strength, so when the cylinder pressures combed with strength that rapidly drops away after 380dF are considered, the concept of keeping CHT's below this limit are somewhat sensible.

 

The concept of taking an engine inside the boundaries of the red box by a fair margin and on an engine that is well below 380dF and running it up to a target limit lets call it of 380dF is not what APS consider to be prudent. The idea is to keep outside the red box (thus ICP's low) and keep CHT's under 380dF. Emphasis on the word "and". So as you have pointed out if you have by good fortune managed to have excellent cooling or in very cold climates achieved a very low CHT, driving the ICPs up further by running say a TC/TN engine at high power and either not very LOP or even not very ROP, this would be a sub-optimal method of operation, and contrary to the intent of the original concept. Remember APS invented the red box concept. The concept of a target CHT is plain wrong. Parade rest!

 

 

 

 

Indeed. There is more to engine operation than a course. Someone that  says "end of argument" has no argument. 380 degrees wasn't just pulled out of air. Saying that a pioneer of this stuff is just plain wrong is a level of incompetence I will not tolerate. We have many people reading these threads that don't participate because they are either here as a guest or learning. We cannot have people giving out wrong information, as there may be an impressionable pilot here that heeds bad advise.

 

Darin, 380dF was not pullet out the air, and I am at a loss as to how you believe Mike was the pioneer here, he was certainly the pioneer of helping spread the truths about engine management, and for that he has done an excellent job. His long running articles are testament to his commitment to helping spread the word. Mike is so committed he has taken the APS class three times. Nobody else has ever done that. Mike is a great guy, but the concept of using a target for CHT is flawed. If you feel that my comments about Mike's 380dF Target CHT are wrong, can I refer you to George Braly, Walter Atkinson and John Deakin, I am happy to send you an email address for a third party and probably far better explanation if you would like me to.

 

As for giving out wrong information, and pilots accepting bad advise, I am 100% with you on that. This is why APS does what it does! And we work really hard at dealing in only data backed facts. Any time we are not sure of things or have not seen enough data to conclusively prove something, we will declare in our opinion we think XXXX is likely to be true. I trust you will support me in this endeavour on Mooneyspace.

 

 

 

There are plenty of people who collect this type of data, just not for a profit.

 

It may surprise you that the kind of data collected over the years from the Carl Goulet Memorial Engine Test Facility was used to develop many commercial products, namely the Gamijector development, TAT turbo and many fuel testing and other FAA engine tests. The knowledge gained was also used to be shared in an educational format known as Advanced Pilot Seminars, and yes there is a cost associated with it, and it is not cheap to present, but as for being a profit purpose, well hardly. Just the cost of the engine Dyno runs would exceed the loose change profits for George, And the hours and hours and resources ploughed in and still provided by Walter and john make it a "hobby farm" type profit, one that might be considered not worth the effort. 

 

It will therefore come as no surprise that the same thing is true here in Australia, and we find ourselves having to charge more due to extra costs of doing business down here. Have a read of the history, 5 pages of it http://www.airspacemag.com/flight-today/church.html?c=y&page=1

 

Just a quick question, the graphic in your user profile, where did that come from? Have you a link to the source?

 

Hope you get better soon and off the drugs!

[DS1980]

I'm not sure where a target CHT method was mentioned, nor have I heard of such technique. I have heard of the target EGT value for leaning, but that's something different and something I wouldn't have a problem with. I have described 380 CHT as a maximum value, as it is possible to be running outside the red box and reach this value.

 

Mike is a pioneer in that he dissimates this information to the masses. I was learning from Mr. Busch long before I heard of APS. I understand a lot of LOP and engine management research has been done by the founders of APS, and I will be a customer of GAMI injectors when I go non-carb, but this information is too important to be kept from the masses and only taught to those with $395 and a high speed internet connection, especially when the engine manufactures say to run 50 ROP and suggest a CHT limit of 500 degrees. Notice I didn't mention Lycoming by name.

 

My thought on APS. Don't get me wrong about the people of APS, as they are aviation GIANTS in my mind. But if you're going to spend decades in this level of research, it cannot be expected to recooperate even a small amount of the investment. This is something that would be done for the betterment of the aviation community and nothing else. I have read testimonials from the students of APS and one in particular struck me as odd. I will quote it directly from the website:

 

"In ten years everyone will be operating the way these guys are teaching." --Dr. Jay Apt, Astronaut Bonanza & Twin Beach Owner

 

Why 10 years? Why not now? Because those that don't know about the teachings of Mike Busch or Deakin's (free) Pelican Perch, this information would be hidden from them. This is why I'm a Busch fan. He is extremely giving with his time and genuinly wants pilots to know how to better their engine managment skills. Because of this, Savvy Maintenance is growing by leaps and bounds. Now there's the business model.

 

Lastly, I do appologize for the harsh words, but you come in here as an "expert" flonting the APS logo. As I stated, there are more than a few on this forum that have been there, done that and have every bit of knowledge as the 2.5 day course. Notice I didn't mention Byron, Chris, Bob, Ross, Tom, ect. by name. Dang it!

 

As far as the graphic goes, it's from EAA webinars by......drum roll.......Mike Busch.