Just Completed APS Engine Management Online Course

[Earl]

I really debated whether this would be worth $395 but I am really glad I took this course.  I can understand why it would be preferable to do this live in Ada so you can ask questions and see them operate their engine on a stand but that wasn't an option for me anytime soon and as I learned from the course I could not afford to wait another day.  I learned a tremendous amount about engine management and am cringing to think I have probably been running my engine too ROP although I wouldn't know because I didn't have an engine monitor installed and I didn't know enough to track TIT, CHT and EGT in any meaningful way other than to avoid redline.  I hope its not too late.....

I would say IMO if you don't have a JPI engine monitor that allows you to track parameters on a cylinder by cylinder basis this course is probably not worth $395.  Simply put, run your engine 100+ degrees ROP or if you have balanced fuel flow vis-a-vis air flow - 50 degrees LOP.  I would be interested if others more knowledgable than I on this topic agree or have a different take.  Some advice for those that plan to take this course, take detailed notes and print out every slide for future reference.  You can only go through each section multiple times until you take the quiz.  After the section quiz you can't go back.  They offer to send you the slides for $100 which I think is ridiculous after having paid $395 for the course.  By the way, on many of the slides there is is drop down so not all the text is displayed at one time so you will need to print several versions of each slide to get all the text (you will probably have to take the course to understand what I am saying).

For sure my next step is to perform the GAMI test to see if my fuel:air ratio between cylinders is close enough to run LOP.  If it passes I will use LOP for sure.  If not, I will be running a lot more ROP than I have been to stay away from the high internal cylinder pressures.

[KSMooniac]

Excellent!  I think you can probably see why many 231s seem to have top overhauls now...

I think the $100 hardcopy is likely the nice, organized notebook we got at the live class, and not just a dump of powerpoint slides.  It includes some excerpts from various POH's as well to show errors in published procedures by the OEM's.  It is worth it IMO, but I suppose printing your own isn't bad either, but of course that isn't exactly free either.

One thing they stressed in the class is that you do not have to have an engine monitor to run LOP, and in fact, running LOP with a single EGT gauge becomes your de facto monitor in that if you can run smoothly LOP, then you know that your induction, fuel delivery and spark systems are all working properly.  If something goes wrong with any of them, you will get rough operation immediately and you'll feel it!  If you are running ROP, then the power loss from any malfunction might not be enough to feel, and you can continue to cruise along fat, dumb and happy.   

If you decide to take the live class in the future, I believe the "tuition" for the on-line course will count towards the live one, so keep that in mind. 

[KSMooniac]

Oh, and after getting the education, I think you might agree that installing an engine monitor is a tremendous bang-for-the-buck upgrade!  If you're into owner-assist maintenance, it is a good candidate for you to do since much of the expense is tedious, but not difficult, installation/routing/securing of the probes that can be done easily by any owner with mechanical aptitude, under proper supervision of course.

[Earl]

Scott:

Thanks for clarifying about the manual and the credit application for the online course.  If I have the time I may try to take the live class at some point.  I completely agree with you about the engine monitor.  It is a critical piece of equipment and like I said, I cringe to think how I have been running the engine without the knowledge from this course and the new EDM-730. 

I also agree that you don't need the monitor to run LOP although as you know much better than I you won't be able to identify which cylinder has a problem like a leaky valve, bad sparkplug or plugged fuel injector.  Tomorrow I am doing my GAMI test and am hopeful my injectors are properly balanced so I can run LOP without more cost.

[Earl]

Perhaps Scott would be better at answering this question since I am a neophyte but my understanding is that for LOP operations 50 dF LOP is a GoFar setting and 25 dF LOP is a GoFast setting (relatively speaking because all LOP operations are otuside the maximum horsepower).  In any event you are right that APS indicates that below 65% power there is no combination of MP, RPM and mixture that should be harmful to the engine....Scott please verify!

If you can't operate smoothly at 25dF LOP then you have different Fuel:Air mixtures in different cylinders which makes the horsepower output of each cylinder dissimilar which causes the rough running engine.  Am I to understand that it is smooth at 50dF LOP or have you never gotten there because at 25 dF LOP it runs rough?  If that's the case you need to really run ROP (maybe 100 dF or more) in high power settings because without engine instruments on each cylinder you could have some running in the dreaded 40 dF ROP where internal pressures are the highest, some running at peak  and some running LOP.  I think by your question you probably already know this.

As I understand what APS is saying, for a turbocharged engine you do all your climbs full throttle, full RMP (unless you need to pull back a little, no more than 200 RPM, for noise abatement) and full mixture.  At cruise after you got all your airspeed back they reduce RPM to whatever is smoothest, leave the throttle wide open (WOT) and pull back mixture to anywhere from 25 dF to 50dF LOP of peak depending upon whether they want to get there a little faster or go farther.  As Scott points out you don't necessarily need the engine instrument to do this but you would losing a lot of valuable information.

[Earl]

As I said I am a neophyte so I may have it wrong about GoFast and GoFar when LOP.  As best I can recollect from the seminar if you are 65% power or less anything LOP won't harm the engine.  And if it is running smoothly at that mixture setting then F:A ratios and horsepower are balanced between the cylinders and assuming CHTs are not above 380 dF and TIT are below around 1,500 dF you should be able to go as long as the fuel and your bladder can stand it. Scott will have to weigh in about why going to 50 dF is desired.  I do know that HP drops off rapidly LOP as does internal cylinder pressure (ICP).  I also know that horsepower per pound of fuel per hour is highest at 50 dF LOP which is maybe what he is referring to.  25 dF LOP will also result in higher EGT and CHT readings but all are less than the peak at 40 dF ROP.

Interestingly, what they said in the course is if your F:A ratios were close enough the engine will run smoothly as you lean it right up until it quits.  Seems to me every plane I have ever flown will become rough at some point as you lean it.

[Magnum]

In the attached graph you can see the power loss when operating ROP / LOP. You loose approx. 3-4 % between best power (100 dF ROP) and peak EGT. When you go on the Lean side, you loose 4-5% between peak EGT and 50dF LOP. That means when the power loss is greater the more you go on the lean side.If all cylinders peak at the same time (NOT same absolute EGT), you won't have any problem operating LOP. You can lean the engine until all cylinders die at the same time. Gami measures this with the gami spread (Fuelflow difference between the first and last cylinder to peak), in this case it woul be 0.

Usually you will have a higher gami spread and that means one cylinders peaks before the last one. I measure that with the EGT difference between actual EGT and peak EGT of each cylinder (don't compare the absolute EGTs between the cylinders, that is worthless).

Lets say the spread between the peaks of your cylinders are 50dF (first cylinder peaks, the last to peak is still 50dF rich of its OWN peak temperature), the difference of power between these cylinders is approx. 2% while ROP, but at 4-5% LOP.

So even when you fly with 60%HP, the power difference between these cylinders is still higher when operating LOP than running ROP at 100% HP. (0.6*0.05 > 1.0 * 0.02)

50dF spread is a lot for a injected engine, I assume 20-30dF is more common (without Gamis).

I recommend to check the EGT differences instead of the Gami spread. Then you'll always know where your cylinders are. Even when flying ROP I set the EDM to LOP operations, I lean until ALL cylinders are LOP and then enrichen as desired. The EDM x30 shows the difference of EVERY cylinder to it's own peak temperature.

To come back to your question: Just "feel" how the engine runs, in my case it depends on the throttle setting and RPM how close together the cylinders peak and sometimes LOP just doesn't feel right and I stay ROP (even at 65%HP).

[KSMooniac]

I agree with just about everything above, except the Go Fast and Go Far settings while LOP.  25 dF LOP is more power/more fuel than 50 dF LOP, so 25 dF LOP = Go Fast, and 50 dF LOP = Go Far.  Both are superior settings to peak or ROP in terms of efficiency, internal pressures and CHT.  The most efficient setting is in the 40-50 dF LOP range, but 25 dF is pretty good while retaining a good amount of cruise speed.  In my plane, I'll typically aim for 20 dF LOP when above 7,000 feet, but in the summer sometimes I need to lean further to keep CHTs below 380 dF.

The other thing to keep in mind for us non-turbo operators is that the dreaded "Red Box" (an APS-coined term) is not constant.  It scales with power output, which means altitude for us.  At 8,000 feet, we can only make 75% or thereabouts maximum power, and with a cruise RPM and LOP power setting it is less.  You need to be "rich enough" to be out of the red box on one side, or "lean enough" to be out of it on the other side.  Thus, the amount of degrees off of peak reduces as power decreases, so at 70% or so 10-20 dF LOP is fine, and by 60% or so you can fly peak or anywhere and the ICP won't be so high as to harm anything.  CHT will still be higher, though.  If flying down low at 80% or 85% power, one needs to be *more* LOP or ROP...like 60-70 dF LOP, or 150 dF ROP.

Turbo guys have it easy...their red box is constant up to the critical altitude of the turbo.  Cirrus got it right with their Turbo SR-22 and their POH puts cruise at WOT, 2500 RPM, and lean to 17.5 GPH.  This is 87% power LOP, about 70 dF LOP I think.  They go faster and burn less fuel than a 75% ROP power setting, while maintaining cooler CHTs!

Regarding your ability to run smoothly at 50 dF LOP...no, you don't really have to, but ideally it would be best if your engine were smooth all the way to idle cut off.  If you typically fly up higher in cruise then 20-30 dF LOP would be fine, but if you're staying low to minimize headwinds for example, it would be nicer to leave the throttle wide open and just pull the mixture back a bit more to stay out of the red box.  The engine is more efficient at WOT since the butterfly doesn't disturb the incoming air.  If your plane cannot get to 50 dF LOP, then you might start looking for a small induction leak first...

[Earl]

Thanks Scott.  I think my original post had the GoFast/GoFar LOP backwards and I corrected it so there would be no misunderstanding.  Part of his challenge is he doesn't have an engine monitor with individual cylinder data.  Having said that, if he wants to operate at more than 65% power and his engine runs rough at 50 dF LOP my understanding from the course is he would be safer to operate at more than 100 dF ROP to avoid staying out of the red box.  Is that correct?

[Magnum]

I'd suggest if the engine doesn't run smooth at 60%HP LOP, I'd fly at peak EGT.

[Magnum]

Quote: ehscott

Thanks Scott.  I think my original post had the GoFast/GoFar LOP backwards and I corrected it so there would be no misunderstanding.  Part of his challenge is he doesn't have an engine monitor with individual cylinder data.  Having said that, if he wants to operate at more than 65% power and his engine runs rough at 50 dF LOP my understanding from the course is he would be safer to operate at more than 100 dF ROP to avoid staying out of the red box.  Is that correct?

[KSMooniac]

If Jim can run smoothly at 20-30 LOP, that is sufficient for typical non-turbo Mooney cruise altitudes of 7-9,000 feet.  If his CHTs creep up above 380 in the summer like mine sometime do, then he might not be able to lean further to keep them cool, and then should go back to 100 dF ROP.  However, I'd still want to fix my engine so that I can run smooth LOP all the way to 100.   

[Cruiser]

what "harm" is being done to my engine by "high" ICP? I understand the red box and assume it is developed by some combination of ICP and CHT. I hear comments about the dreaded red box but not what those evil things are doing to my engine. If I run with slightly higher ICP, that is, I am only slightly on the edge of the red box how does that change what happens inside my engine.

does it increase wear on components?

does it burn valves?

does it damage rings?

The only reasons I hear engines needing top overhauls are because of low compression or burned valves. What am I missing?

[Earl]

My understanding from the APS course is that the combination of high ICP and high CHT is harder on pistons, valves and spark plugs and may cause premature failure.  CHT and ICP tend to mirror each other so if you are operating at peak CHT you are also operating at peak ICP and it stands to reason that if you can operate the engine within a reasonable range of performance and cooler and at lower pressure inside the cylinder that is a good thing.  I think the bigger issue is running at the edge of the box leaves little room for error and any issue like a failed plug or plugged injector can quickly spiral out of control although I would guess otherwise is not a problem.

My understanding of top overhauls is similar to yours but you have to ask why the rings are shot or the valves are damaged.  In the course they go into a lot of detail about the thermal boundary layer between the metal parts of an engine.  When CHT and ICP are high the thermal boundry is reduced and heat flow away from the cylinders is diminished.  Left to continue you risk a thermal runaway where the valves and/or pistons will rapidly fail.  So operating at the edge of the red box leaves little room for error to correct a situation like that before it goes really bad.  Whether in the real world this additional time is of any value I don't know.  I think the other thing you risk with high CHT/ICP is spark plug failure which in the right circumstances can lead to pre-igntion of the fuel in the cylinder and catastrophic failure.  I know I am not doing this topic justice but that's my recollection from the course.

[KSMooniac]

The higher the ICP, the more stress is placed on the cylinder itself, as well as the piston, rings, connecting rod, crank, bearings, valves, etc.  Higher stress and higher heat are harder on all metallic components, so minimizing those things will increase the fatigue life.

[carusoam]

For comparison, it may be helpful to know - M20R Continental IO550G:

From the POH: 

Best Power = 50deg ROP

Best Economy = 50deg LOP

This is based on a single EGT and CHT instrument.

From Max Power at Sea Level: 27", 2500rpm  Best economy 15.3gph  Best Power 17.6

Lowest Power 45% power at 20,000: 12.3" - 2300rpm Best economy 8.2 gph  Best Power 9.8 gph at 2500 rpm

What this indicates - Best thing to do: Balance air flow and injector flow.

-a-

This engine has the balanced induction (equal length tubes) and nicely balanced injectiors. 

I also have the JPI 700, so I know my GAMI spread = 0 gph.

When leaning it will shut off on you without vibration.  Surprisingly smooth.

My M20C with the O360, carburetor was unable to even go to LOP.  The spread must be huge.

 

 

 

 

[fantom]

If they mention it at all, what does APS say about the increased EGT's running LOP? New exhaust systems aren't cheap.

[KSMooniac]

The raw values of EGTs are essentially meaningless in terms of exhaust life.  They are only useful as tools for monitoring engine performance and diagnostics, which is why the OEM single EGT instruments only have a scale with no numbers.

[Cruiser]

I thought the EGTs went down when operating LOP?

[KSMooniac]

Well, they go down from peak...but 50 ROP is the same temp as 50 LOP.    If one is operating at 100 ROP and then goes to 20 LOP, the EGTs will be higher.  CHT and peak ICP will be lower, which is the most important concept.

[KLRDMD]

Quote: KSMooniac

One thing they stressed in the class is that you do not have to have an engine monitor to run LOP, and in fact, running LOP with a single EGT gauge becomes your de facto monitor in that if you can run smoothly LOP, then you know that your induction, fuel delivery and spark systems are all working properly.  If something goes wrong with any of them, you will get rough operation immediately and you'll feel it!  

[Jeff_S]

Well, I haven't paid the $395 but I feel like I've gotten a good chunk of that info here and at AvWeb, and the results bore fruit today.  Just went out for a test hop with my "red box avoidance" chart pulled from AvWeb (attached) and a refresher on how to use LOP ops on my JPI-700.  I got up to 5500 and went to work.

First, tested my GAMI spread using the LOP feature: 0.2.  Sweet! No need for GAMI injectors.

Next, used the chart to lean down to -20 LOP and just let 'er stabilize at WOT and 2450 RPM.  She settled in at 155 KTAS and about 9.5 gph.  And the CHTs stayed all below 350, some down around 320. Even the old analog CHT and Oil Temp gauges got lower than I've seen them for awhile.  This stuff really works!

Many thanks to all for bringing me along for the ride with all the info.

[KSMooniac]

Sweet!  I'm not surprised one bit.    9.5 GPH = 71% power when LOP.  That is a perfect power setting for a J at 5500'.

[fantom]

Quote: KSMooniac

Well, they go down from peak...but 50 ROP is the same temp as 50 LOP.    If one is operating at 100 ROP and then goes to 20 LOP, the EGTs will be higher.  CHT and peak ICP will be lower, which is the most important concept.

[Earl]

Great news Jeff.  Did you fly today?  I went over the KRMG arouind 10:30am to pick up a radio and spend a few minutes with the MSC on operation of the EDM-730 and returned about 12:30pm.  I tried operating LOP but it was not smooth.  He looked at my max fuel flow and it is too low.  Running at 20.3gph at WOT and full rich.  Need to get that dialed up a bit even though it is within book values.  My EGT difference was 90 dF.  I think I need some engine and injector tuning before I will be able to run LOP.