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Engine leaning with EDM 700 in M20R ovation


r0ckst4r

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I have an Ovation 1 with a JPI EDM 700 and 450 fuel flow monitor.  At cruise I follow the instructions to pre-lean first and the use the lean find to lean to 50 LOP.  What usually happens is everything goes well, it finds the leanest cylinder then find the richest cylinder and I continue leaning until I am at about 20-30 LOP and I notice a change in engine smoothness.  I then enrichen the mixture slightly for smoothness.  I can't seem to ever reach 50 LOP.  It seem I'm doing nothing more than the old pull to engine roughness then enrich mixture that was done before engine monitors.  All the CHTs are fine and my fuel flow is less than expected by the performance chart in the POH.  Should I continue to do things this way?

An additional note.  I had found this article

https://www.jpinstruments.com/wp-content/uploads/2013/05/Mike-Bush-Red-BoxRed-Fin.pdf

It seem like the leaner the better but I just want to make sure I'm not running too close to peak or that there is some other problem stopping me from getting to 50 LOP

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Rock,

Your details are indicating you are missing some detail...

Let’s see if we can determine what you are missing...

When you set up the JPI to run LOP or ROP... it should determine what cylinder it is going to do the work from...

When LOP, it is last to peak...

When ROP, it is first to peak...

Your experiment WILL be altitude dependent...

When running LOP and going 50°F LOP at 10k’... this IS the same as run til rough, then enrichening....

At 5k’ a well balanced intake system is able to run 90°F LOP...

 

An IO550 that is well balanced at delivering air/fuel can run smoothly until the power shuts off...no rough to run to...

 

Set your expectations... why are you running so deep in the LOP zone?

Have you run the Gami spread test?

Running LOP has some advantages...

But running deeper LOP doesn’t get any more advantages... (leaner is NOT better for everyone...)


my thoughts...

in cruise, above 8k’... below 65% hp... out of the red box....

MP set to max... most air available...

Mixture set to a few degrees LOP.... max FF that gets used to develop power...  (I want to go fast, LOP for fuel burn efficiency)

RPM of choice... 2500 or 2550 if able...

FF ROP will be around 15  GS will be about 175kts

FF LOP will be around 13  GS will be about 165kts

 

PP thoughts only, numbers off the top of my head... could have some errors in it... :)

Anything odd or interesting stand out?

Best regards,

-a-

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the more information you provide the better the responses will be.

1. did you do a LOP test ? what is the spread between richest and leanest ?

2. what altitude ?

3 what MP/RPM settings

4 what fuel flow rate at LOP settings.

much the same questions as mentioned above ^^^

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21 hours ago, r0ckst4r said:

What usually happens is everything goes well, it finds the leanest cylinder then find the richest cylinder and I continue leaning until I am at about 20-30 LOP and I notice a change in engine smoothness.  I then enrichen the mixture slightly for smoothness.  I can't seem to ever reach 50 LOP

If you’re trying to manage strictly to the Busch article (where the majority of his answers are quite simply “it depends”), you won’t get to 50 LOP doing this.  By hitting 20-30 LOP and then enriching to “smoothness”, you’re putting yourself closer to peak...BUT, that may be ok for you and it may not.  The article contains good questions and common-sense answers.  Some more questions to help guide you (I’ll summarize from my earlier post and include some from @carusoam, @Cruiser, and @Niko182 above)...

  • What type of plugs do you have (massive or fine wire), and what brand?
  • When was your last annual, and with whom?
  • How many hours on your current engine?
  • What make/model of ignition harness do you have?
  • Do you have GAMI injectors, or the stock CMI injectors?
  • Do you have the 310HP STC, or stock 280HP engine?
  • What altitude(s), MP, and RPM settings are you using when attempting to get to LOP?

Again, just some starter questions to try getting you closer to your goal.  Your original post is a good one.  There may be nothing wrong with your engine...just some procedural things to get you to a better place of understanding and operating more efficiently.  Also would help to know what portion of the world in which you’re based, as environmental factors also play into the above.

Steve

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8 hours ago, StevenL757 said:

If you’re trying to manage strictly to the Busch article (where the majority of his answers are quite simply “it depends”), you won’t get to 50 LOP doing this.  By hitting 20-30 LOP and then enriching to “smoothness”, you’re putting yourself closer to peak...BUT, that may be ok for you and it may not.  The article contains good questions and common-sense answers.  Some more questions to help guide you (I’ll summarize from my earlier post and include some from @carusoam, @Cruiser, and @Niko182 above)...

  • What type of plugs do you have (massive or fine wire), and what brand?
  • When was your last annual, and with whom?
  • How many hours on your current engine?
  • What make/model of ignition harness do you have?
  • Do you have GAMI injectors, or the stock CMI injectors?
  • Do you have the 310HP STC, or stock 280HP engine?
  • What altitude(s), MP, and RPM settings are you using when attempting to get to LOP?

Again, just some starter questions to try getting you closer to your goal.  Your original post is a good one.  There may be nothing wrong with your engine...just some procedural things to get you to a better place of understanding and operating more efficiently.  Also would help to know what portion of the world in which you’re based, as environmental factors also play into the above.

Steve

Let see if I can get you guys some more information here

The logs show RHB32S fine wire plugs

The last annual was at AGL last month

Current engine has 668 hours

I do not know the ignition harness details

I have to assume that the injectors are stock CMI injectors as I cannot find anything in the books about them.

This engine is the IO-550G 280 hp engine with redline at 2500

I have attempted LOP at multiple altitudes and power setting, here is what I got today.  4000ft, 65% power 19.7MP/2500 RPM, I was able to get to 50 LOP fine and my fuel flow was 10.2 gl/hr (12.0 gal/hr is listed on the chart in the POH).  GAMI spread on the EDM 700 was 0.4

After climbing to 5,000ft at 65% power 19.5/2500 RPM i was only able to lean to about 30 LOP before change in engine smoothness after which i enriched to about 15-20 LOP.  Similar fuel flow.  GAMI spread was 0.2.

The engine runs well, I just worry that something is off with my leaning and I'm actually way below 50 LOP despite what my EDM tells me.  However my consolation is the article I posted seems to suggest that running too lean of peak may affect power and such but will not be hazardous to the engine (other than shutting it off from fuel starvation I imagine).  All my CHTs have been <350.

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Something is definitely wrong. 

If you really have a 0.2 gph FF spread you would never "feel" roughness. Think about it. Roughness comes from unequal power between cylinders. 

You might do a lean mag test

also, 10.2 gph is not 65% power LOP on an IO-550, it is more like 54% per calculations

65% should be 12.2 gph

 

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Bump the MP up to 23 inches.  Leave the RPM at 2500 and repeat your tests.  Also try testing at higher altitudes...suggest 6, 8, 10, and 12k (or 7, 9, 11, and 13...or a combination...your choice).  As MP decreases below 23 inches as you climb (generally ~8000), increase MP to wide-open throttle (“WOT”).  Then lean to 40 or 50 LOP.  Everything else you’re telling me above doesn’t sound remarkable.  Lastly, make sure your takeoff fuel flow is between 24 and 25gph.

Parenthetically, according to Bob Kromer (former test pilot for the company), consider full-throttle operations above 3000 feet.  Partial-throttle operations as you described above tend to compromise efficiency in tuned induction engines such as the 550, and do not take advantage of available power.

Let me know how your additional tests go.

Steve

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sounds like you are getting closer...
 

WOT takes one of the variables away... a throttle plate is known for disturbing airflow...
 

When finding peak... lean really sloooowly...

There is a lag between spinning the red knob, and when the new temp shows up...

If spinning constantly while reading temps... they won’t be very exact...

 

A Gami of 0.4 is somewhat large..., less ideal...

A Gami of .1 or zero... the power will just shut off instead of going rough...


 

If you overshoot while finding peak... you can always rotate the knob back... it should be repeatable... the peak won’t change... unless you are spinning the knob too fast for the EGTs to catch up...

This is the reason they talk about pre-leaning...without pre-leaning, if you go slow enough to see the EGT rise each time... the flight will be over before you complete setting the mixture... :)

PP thoughts only, not a CFI...

Best regards,

-a-

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Before really trying to fly LOP, you should really verify the engine is currently meeting the pre-req's to be able to do. A good gami spread is not the only requirement. You also need to have a healthy ignition system that is misfire free upto at least 50F LOP. You've mentioned above that your Gami spread is quite tight, that needs to done very slowly. I can demonstrate 0.0 spread by turning/adjusting the mixture too quickly. So I suggest you follow our Savvy Test profile located here on Savvy https://www.savvyaviation.com/home/resources/flight-test-profile/ You may well learn a lot by just absorbing its details and following it. As the instructions state, do the test WOT, it has to be done this way to get the best data, and not above 65% power.

Additionally, 50F LOP is way too lean for 65% power setting . That's the correct for 75% power, but I don't suggest trying to run at 75% LOP till you fully master the techniques. Since at 75% power its not safe to use the Lean Find method with your JPI. But at 65% power 15F LOP is all you need. For more info on these concepts, see the thread from last week that someone posed the same questions about leaning below. Although the question was for a turbo engine, the theory and concepts and guidance on where to leave the mixture are no different. The main difference is that your preferred way to set up for LOP cruise at higher power levels (if you ever go there) will be with the big pull. But its fine to use your engine monitor to lean to LOP as long as you stick to power levels no higher than 65%. 

For now though, fly the Savvy Test profile to evaluate your mixture and ignition. It takes both to be able to run LOP. Most understand the need for good gami sweeps but many miss the importance in ignition. A lot of questions about maintenance, engine setup, HP etc which really don't have any relevance till you've flown the equivalent of the Savvy Test profile and actually know what you have for mixture and healthy ignition.  

One more critical point I can't emphasize enough, make sure you set your engine monitor EDM to its fastest data sampling rate, which for the 700 series will be 1-2 sec depending. The default 6 rate is much to coarse to get reliable repeatable results. Instructions for how to do this are in the the Savvy Test profile. After you have flown the profile, you can upload the data into a free Savvy account to look at and measure the spreads etc.

 

Edited by kortopates
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I managed to do some flying this week and followed those instructions.  Here is what I ended up with:

9,500 ft,  WOT, MP 21, 2500 RPM

100 ROP my fuel flow was 15.0

LOP (as described in the instructions) about 11.0

The LOP mag test was fine, The engine ran just mildly rough on the left or right mag alone but not overly rough and smoothed out on both.

I'm thinking that I was just overthinking the numbers and should just pay attention more to the article that I linked in the original post.  I also have stated to adopt the technique described in it with a relatively fast mixture pull and slowly finding peak "backwards" from already LOP and finding -50 (or roughness) that way.

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How lean did you go?

Why did you go so lean?

 

Looks like you have a good feel for the instrumented leaning process...

Sneaking up on peak from one side or the other won’t make a difference...

The delay in instrument response is quite long...

If you don’t have a feel for how long it is... more practice will probably help...

knowing where the peak generally occurs, really helps...

 

There is an interesting device available on the market called AutoLean.... ask @takair for details if interested...

Best regards,

-a-

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On 3/28/2020 at 4:17 PM, carusoam said:

How lean did you go?

Why did you go so lean?

 

Looks like you have a good feel for the instrumented leaning process...

Sneaking up on peak from one side or the other won’t make a difference...

The delay in instrument response is quite long...

If you don’t have a feel for how long it is... more practice will probably help...

knowing where the peak generally occurs, really helps...

 

There is an interesting device available on the market called AutoLean.... ask @takair for details if interested...

Best regards,

-a-

As per the instructions provided by SavyAnalyisiPro I leaned to the onset of roughness then enriched slightly to smoothness.

From what I have been reading finding peak backwards from the lean side is described as being safer for the engine and avoiding more time in the red box or fin.

I do notice that I have to adjust the mixture quite slowly for the instrument readings to "catch up".  Which makes more more comfortable doing that after the big mixture pull and already on the lean side.

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Which altitudes do you prefer?

how/why are you selecting your lean target?

I typically fly around 10k’... and lean a few degrees LOP...

This converts all the gas to power, none wasted on cooling...

Producing as much power as is available to the NA engine...

With the O1 engine...I was limited to 2500 rpm...

With the O3 power plant... 2550 just because I can...

 

At high power settings over 65%... Going LOP has some challenges...

At lower altitudes I use the MP knob to dial things down...

50°ROP read about the challenges... wrong place to be...

50° LOP compressing a lot of air to use as a coolant... but can be better than lowering MP...

Either way... watching CHTs is a big driving force... or using more FF, or AF...

Reading the Savvy details or the books by the same author... is great back ground...

The question is... how do you tailor it to fit what you want to do?

How well are you controlling CHTs?

Have you found an LOP speed and an ROP speed that you like?

Mine were 175 and 165 ROP/LOP generally... 15gph 13gph roughly...

Best regards,

-a-

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If you want a fundemental understanding how how to properly lean go up to 9000ft where theres no chance of hurting your engine. Set the rpm at whatever you like to cruise at, be that 2550 or 2300rpm whatever doesnt matter, and set throttle to wide open

Bring an Ipad with excel downloaded on it and on the X axis of the excel sheet put the egt numbers 1 through 6. On the Y axis put fuel flows. Id start with 18ish gallons, and write down the EGTs for all 6 cylinders. Go down to 17.9gph. List them on. Down to 17.8gph... 17.7... 17.6 all the way down until the engine gets rough. Give the engine 10 to 15 seconds everytime you change the mixture in order to let the egt's set. Youll be around peak for a couple minutes but you shouldn't have any issues since you're not creating a ton of power. Once you get to about 13.5 ish gallons per hour, EGT's should start dropping. And going back down.

Once you're done logging all of that and after you land take a look at the numbers. Find the highest EGT at each cylinder and see how far apart they are between fuel flows. If EGT #1 peaks at 13.8 GPH and EGT #4 peaks at 13.1gph, you have a gami spread of 0.7gph. That gami spread is shit and will result in poor LOP procedures. If all your cylinders peak at 13.4gph, then your gami spread is 0gph and that should result in pretty good LOP operations.

Once you figure those numbers out you'll know which cylinder to look at when leaning. You want to lean (N)° degrees from the cylinder that peaked at the lowest fuel flow, N being equal to temperature. 

This is a pretty good way to start figuring out peak and LOP flying.

I would not do this below 7500ft,but since you have an O1 powered ovation with only 280hp, i doubt you'll be able to hurt it anyway.

Edit: I added the results I got when I did it a couple months back before I got gami injectors. I think I did this at 8000 ft. if you look closely you can see the numbers in bold are where each EGT peaks. In this case I had a Gami spread of 0.4 gallons per hour which is alright, but it could be better.

as an example If i wanted to be 30 degrees lean of peak I would set the JPI 700 to show the EGT of either #3 or #5 since those are the last ones to peak. ill chose #5 since 1580 makes it easy. I'll take that 1580, subtract 30, and i would want the value of EGT #5 to be 1550 in order to be 30 degrees Lean Of Peak.
 

Once you get the hang of it, you'll start to remember the fuel flows and just lean to a given fuel flow instead of looking for an exact LOP temp. Autolean is a cool feature, but it won't give you the understanding how to lean any piston engine if you have a basic EDM700 or insight monitor.

Sauce.JPG

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42 minutes ago, r0ckst4r said:

The AutoLean device look very interesting but as I have been finding out the despite what the POH says a specific EGT temp like 50 LOP or 50 ROP does not seem to always result in the correct mixture given all the variables. 

Something isn’t fitting properly...

The point of basing the leaning off peak EGT... is to remove all the variables....

You know generally where peak is going to occur... based on FF... and your total experience so far...

Get in the neighborhood and spin slowly from there... if the temps are going up... continue to spin the knob to the left slowly...to approach peak... if you go past peak... spin the knob slowly to the right again watching the EGT rise with the FF...

Note the FF while keeping an eye on the EGT...
 

As far as automating it goes... it is a motorized system that does exactly that... Ask Rob for more details if interested... Rob /  takair is the STC writer for that device... the knob probably has various set points for common °F LOP/ROP....

The JPI is pretty good with the LF mode... it takes getting used to... setting the mode properly so it does LOP and doesn’t revert back to ROP the next day helps... :)

Trying to lean while the EGTs are still cycling through all of the cylinders can cause a hassle...

all stuff I learned to fine tune over the first two years of M20R flying...

So much gets standardized as your IO550 experience spreads out...

Leaning to roughness has completely taken the precision instrument out of the loop...

For fun... lets post some JPI data...  the first time can be quite challenging... the run-up will be messy, the leaning will be messy... it never looks quite like the perfect flights on the Savvy site... until you get some SOPs in mind... :)

With the savvy site, you can probably pull up some flights that were related to Transition Training... where your CFII went through the process stepwise... or the prior owner went through the 100 steps of a flight in a nice order...

PP thoughts only, not a CFI...

Best regards,

-a-

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