Leaning / GAMI Questions

[alextstone]

I just had GAMI Injectors installed on my Mooney Bravo.  My wife, Denise, and I flew for about an hour and she diligently recorded data as I leaned.  See attached.  I discovered the following:

1.  I had great difficulty precisely adjusting the flow .3 GPH in the area near the peak.  Is this a normal frustration?

2.  The fuel flow seemed to wander about .2-.3 GPH - in other words, I would set the flow, start recording data and look back to see that the flow had changed -  is this normal?  Did I not wait long enough for it to settle in before recording data?

3.  The #4 cylinder was changed 25 hours ago on this aircraft.  It happens to be the one that peaked earliest and between it and the #5 cylinder, there was a 1 GPH spread.  Should I allow the #4 cylinder to break in longer before requesting new injectors or will that not make any difference?

4.  This question I feel I should know the answer to but I cannot seem to reason it out so...Owing to the fact that the engine is producing the same manifold pressure regardless of altitude, once the desired fuel flow for 50 degrees LOP is determined, can one set the mixture based solely on that fuel flow regardless of altitude and OAT and expect the engine to run at a consistent 50 degrees LOP?

 

Thanks in advance for your help.

 

Alex

 

[gsxrpilot]

Disclaimer - I don't own or fly a Bravo.

What instrument is giving your FF? I had a Hoskins in my 252 that seemed to wander all over the place. I get much better data from my EDM-900. So yes, I had the same problem. And that makes it pretty impossible, in my mind, to do a proper GAMI check that is indicative of anything.

If you do it again... I'd start at 18 gph, let it settle down there, and then start the test. Just make sure you're at low power, 65% or less. Then I'd run the test slower and ultimately trying to get it to move just 0.1 gph at a time.

But to answer #4, yes for a given MP/RPM (%power) I just set LOP base on FF. In my 252 (also turbo) that's 9.6 gph at 65%.

[kortopates]

Alex, you can't possibly do what you are trying to do with pen and paper. You don't have the data resolution. You need a monitor with 1-2 second downloadable data resolution. Unfortunately, the every 0.5 GPH resolution you tried to record makes it worthless.
Just maybe you got the cyl rankings from leanest to richest. That's very helpful if true, but I wouldn't trust your data till you demonstrate it's repeatable.

Honestly, the first step should have been an engine analyzer with FF, MAP and RPM.

Next read up on LOP, I suggest Mike Busch's article on Red Fin - you can download it on our Savvy website.

Next, start with baby steps, after the engine monitor. See the GAMI AFMS supplement for mixture guidance - between Mike's article and the GAMI AFMS I mentioned note you only need 50 LOP at 75% and I can tell you your engine most likely won't support 75% with 50 LOP. So start at ~60% power which is just a little LOP.




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[N201MKTurbo]

I find that if you peak the cylinders one at a time and then record the fuel flow it is easier.

I know some people recommend recording it as you slowly lean it or richen it through peak and then look at the recorded data. I don't trust that as much because of settling time. There is no way to tell how much the readings are lagging the real temperatures. About all you can hope for is that they are all lagging the same amount. 

The one advantage to recorded data is you can filter out the noise in the readings by just drawing a line through the center of the noise and use that.

If you recorded it in both directions you could find the phase shift caused by the lag and average it out.

As far as running LOP, I used to set the mixture by fuel flow, but my fuel flow gauge is a bit unstable too and I have been using TIT lately and I get much better results.

 

[alextstone]

Thanks for the responses. The airplane has a JPI 700 with data recording and a Shadin Fuel flow meter but unfortunately the FF meter is not connected to the JPI (yet).  Ultimately, I plan to modernize with either a JPI 830 or 930 but for now, I have what I have.  We just bought the airplane three weeks ago and the wife is a little weary of the negative cash flow with insurance, annual, undiscovered TKS pump problem at the pre-buy, GAMI's, etc. 

So @kortopates and @N201MKTurbo, please advise me as to how you would gather somewhat useful data (if possible) within the limitation of the monitors I currently have.   

[kortopates]

Thanks for the responses. The airplane has a JPI 700 with data recording and a Shadin Fuel flow meter but unfortunately the FF meter is not connected to the JPI (yet).  Ultimately, I plan to modernize with either a JPI 830 or 930 but for now, I have what I have.  We just bought the airplane three weeks ago and the wife is a little weary of the negative cash flow with insurance, annual, undiscovered TKS pump problem at the pre-buy, GAMI's, etc. 

So [mention=7862]kortopates[/mention] and [mention=7464]N201MKTurbo[/mention], please advise me as to how you would gather somewhat useful data (if possible) within the limitation of the monitors I currently have.   

To get started, you can wire your Shadin FF sensor in parallel to your EDM 700. You may need to enable the FF option with JPI's help (firmware update) or just go into program mode to turn it on. But if your model doesn't have memory with downloadable data, this won't be very helpful. (JPI use to add that as a $200 upgrade years ago.) But otherwise for same cost of your injectors you can buy the 830 color display as an upgrade returning your old one and be 10x ahead WRT your needed modern analyzer, then add MAP and RPM sensors when you are able. Your existing harness will plug into a new 830 display. You do need a little panel space to fit it somewhere.

 

I see it has data recording, so a USB connection will allow you to apply a firmware update if it's needed to enable FF.

Set the data recording interval from it's 6 sec default to it's fastest - which is 2sec.

 

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[alextstone]

34 minutes ago, kortopates said:

To get started, you can wire your Shadin FF sensor in parallel to your EDM 700. You may need to enable the FF option with JPI's help (firmware update) or just go into program mode to turn it on. But if your model doesn't have memory with downloadable data, this won't be very helpful. (JPI use to add that as a $200 upgrade years ago.) But otherwise for same cost of your injectors you can buy the 830 color display as an upgrade returning your old one and be 10x ahead WRT your needed modern analyzer, then add MAP and RPM sensors when you are able. Your existing harness will plug into a new 830 display. You do need a little panel space to fit it somewhere.

 

I see it has data recording, so a USB connection will allow you to apply a firmware update if it's needed to enable FF.

Set the data recording interval from it's 6 sec default to it's fastest - which is 2sec.

 

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Thank you!  

[Bryan]

Alex, I had your similar setup two to three months ago: EDM 700 with separate FF (Shadin). The EDM helped me find peak and run ROP but realized I could not really get the data I wanted to find LOP settings or capability. I have a 252 like both the two above but data collection should be the same for the Bravo engine.

I, too, found my FF reading in the Shadin very haphazard. I tried to narrow down the K-Factor settings for it to be accurate but could never get it stable thru multiple tank loads of fuel. 

I finally traded in the 700 for an 830 with the extra MAP and RPM probes and added the JPI FF probe over to the 830. Now I have the amazing data and in-cockpit quick analysis of that data all on a single screen/page with % HP.

I am working directly with Savvy using my uploaded data to see trends and tune my engine. All I have left is to get the GAMIs needed to balance my FF as shown from the data. They have been great to work with (Paul) and pointed out some easy changes to make for WOT fuel-flow to keep my engine happy.

I do hear you on the new acquisition costs and new-to-you random expenses that come up. Mine are starting to settle and wish I would / could have done the full engine monitor from the start - it’s so worth the $$$.

[carusoam]

Keep in mind the TSIO540 is not the most LOP friendly engine to work with...

It’s intake ‘log’ style is missing the balance that is found on some of the more modern ‘curvy’ intakes...

So... the better your data handling is, the better your LOP skills will become.

It is definitely possible to run the Bravo’s engine LOP.  But the power setting you get with that will take some work to define...

There is a thread around here that covers Bravo Ops, LOP...  John the lawyer spent a fair amount of time working through the challenges and documenting what he found... before going twin Commander?

Many Bravo operator’s appreciate speed over efficiency, and not being able to go LOP doesn’t seem to be a bid deal for them...

The JPI700 can be connected to FF and GPS for keeping an eye on fuel available related to your flight plan... Promise yourself to not run out of fuel....

First year of Mooney ownership can be rough, traditionally...  don’t be in a rush to over-spend...

But, an updated JPI would be great thing to put on the short list...

Setting the JPI700 to collect data every two seconds is a must do today kind of thing... the downside is running out of data space every two or three years....

Get a Savvy account and store your data over there...

Newer JPIs have the one second option and gobs more memory and capabilities to really improve on flight data recording...

While you are putting your update list together.... Cies fuel gauges are an improvement over the original equipment....combine with your JPI930...

Best regards,

-a-

[jaylw314]

4 hours ago, alextstone said:

Thanks for the responses. The airplane has a JPI 700 with data recording and a Shadin Fuel flow meter but unfortunately the FF meter is not connected to the JPI (yet).  Ultimately, I plan to modernize with either a JPI 830 or 930 but for now, I have what I have.  We just bought the airplane three weeks ago and the wife is a little weary of the negative cash flow with insurance, annual, undiscovered TKS pump problem at the pre-buy, GAMI's, etc. 

So @kortopates and @N201MKTurbo, please advise me as to how you would gather somewhat useful data (if possible) within the limitation of the monitors I currently have.   

I had the same setup with my EDM-711 when I bought my plane--there was no FF recording.  Sending it out to JPI to install the FF costs $195 plus labor and a couple weeks of turnaround.  I had some other stuff done at the same time, but I'm guessing it would be about $350-400 total.  Well worth it even if you plan on investing in an 830 or 900 later on.

Interestingly, the FF readings from the sensor (I have a Floscan) are updated much more quickly on the EDM-711 than the EI FP-5L display, with changes in FF being displayed within half a second on the EDM and as long as 2-3 seconds on the FP-5L.  I wonder if most FF meters average their results over a few seconds, and so have slower responses...

[jaylw314]

4 hours ago, kortopates said:

To get started, you can wire your Shadin FF sensor in parallel to your EDM 700. You may need to enable the FF option with JPI's help (firmware update) or just go into program mode to turn it on.

At least when I talked to JPI, they said adding the FF option requires a hardware change, and the unit needed to be sent in.

[Awful_Charlie]

9 hours ago, alextstone said:

1.  I had great difficulty precisely adjusting the flow .3 GPH in the area near the peak.  Is this a normal frustration?

2.  The fuel flow seemed to wander about .2-.3 GPH - in other words, I would set the flow, start recording data and look back to see that the flow had changed -  is this normal?  Did I not wait long enough for it to settle in before recording data?

3.  The #4 cylinder was changed 25 hours ago on this aircraft.  It happens to be the one that peaked earliest and between it and the #5 cylinder, there was a 1 GPH spread.  Should I allow the #4 cylinder to break in longer before requesting new injectors or will that not make any difference?

4.  This question I feel I should know the answer to but I cannot seem to reason it out so...Owing to the fact that the engine is producing the same manifold pressure regardless of altitude, once the desired fuel flow for 50 degrees LOP is determined, can one set the mixture based solely on that fuel flow regardless of altitude and OAT and expect the engine to run at a consistent 50 degrees LOP?

Alex

 

Welcome fellow Bravo owner!

I'm a LOP convert, and I'm also in the throes of GAMI adjustments having just changed engines (at 2200 hours, the fuel pump and exhaust system were getting tired, the final straw being the original cylinders wearing out)

To take each of your questions in turn:
1) Without a data logging JPI, you've been given some options above, but I would suggest leaning very slowly, letting it settle, and then taking the readings. Might need a long cruise segment to get enough points though! (I had a long cruise segment a few weeks ago which I used too get myself in the right GAMI ballpark. Process after establishing the cruise was just to tweak the mixture out a little (say about 1/5 turn on the vernier) every minute or so - if the fuel flow doesn't settle to a value that averages out 0.1 or 0.2 lower than the previous sample then richen up and do it again! I spent 40 minutes getting down from 18 to 13GPH (easy airspace with minimal ATC interruption)
2) The readings jumping up and down up to 0.2GPH without touching anything seems to be frequent on mine.  This seems to be an instrument thing (it's counting pulses, so maybe it is a pulse  just in or out at the start and/or end of the measurement cycle). I have the original Shadin Miniflow and the JPI running from the same (Flowscan) sender, and the Shadin is noticeable more damped than the JPI, to the point the Shadin lags the JPI by maybe a GPH or more when leaning
3) Maybe worth getting another 10-25 hours on that cylinder - when you consider it fully run in, then that is what you are going to set up for. Remember you get so much tweaking time with GAMI for an install (a year I think)
4) Although the MP may stay the same over an altitude range, the temperatures do not (IAT is the one the engine cares about), and it is overall air density that affects the mixture. In the POH you will see the fuel flow for an MP setting varies a little with altitude, with a small temperature correction too. I would also suggest 50 LOP is the lean limit unless you are CHT limited - when you go further LOP not only is the power is dropping off but the BSFC is getting worse too. I find that at 30" 2200 I can keep everything happy at about 10 to 20 LOP

When you get your data logging with a JPI sorted out, by all means choose a sample period to suit yourself, but I would suggest using the lean find option which then sets the interval to 1 second until you exit the function, and a normal reduced rate will then increase the length of flight time the unit can store.

 

[Txbyker]

Use your cell phone and video the event then when at your computer advance the peak frame by frame to see the values.

Russ

[jaylw314]

18 hours ago, alextstone said:

4.  This question I feel I should know the answer to but I cannot seem to reason it out so...Owing to the fact that the engine is producing the same manifold pressure regardless of altitude, once the desired fuel flow for 50 degrees LOP is determined, can one set the mixture based solely on that fuel flow regardless of altitude and OAT and expect the engine to run at a consistent 50 degrees LOP?

Remember, MP is not an indicator of airflow, it is technically MP * RPM that approximates airflow (temp and volumetric efficiency are other factors).  Also, once you get near peak, EGT changes become much more sensitive, so simply setting a fuel flow might give you a good starting point, but is probably not accurate enough and needs to be fiddled with further.

Edit: We have different motors so the numbers do not apply, but to simplify leaning, I'll set my MP and RPM both to about 25, and the lean until I'm at 9 gph.  9 gph corresponds to about 65% power.  I don't particularly care how many degrees LOP I'm running if I'm below 65%, because I'm out of any danger area.  By experience, I know that MP/RPM setting will be LOP and not run rough at 9 gph.

On the other hand if you want to run at any higher fuel flow, or if you can't reach 25" MP, you will have to fiddle as above...

[Rick Junkin]

On 9/17/2018 at 3:20 AM, Awful_Charlie said:

1) Without a data logging JPI, you've been given some options above, but I would suggest leaning very slowly, letting it settle, and then taking the readings. Might need a long cruise segment to get enough points though! (I had a long cruise segment a few weeks ago which I used too get myself in the right GAMI ballpark. Process after establishing the cruise was just to tweak the mixture out a little (say about 1/5 turn on the vernier) every minute or so - if the fuel flow doesn't settle to a value that averages out 0.1 or 0.2 lower than the previous sample then richen up and do it again! I spent 40 minutes getting down from 18 to 13GPH (easy airspace with minimal ATC interruption)

I employed this same/similar technique, a very slow and deliberate leaning process with 10-15 second pauses at each 0.2 gph increment. I synched the clock in my JPI with my watch, to the second, and manually recorded only the fuel flow with time stamps to later correlate with the temperature data I downloaded from the JPI 700. This makes the manual recording task much less demanding. You said you have data logging on your JPI 700, are you able to download it? If its an older installation it requires a special cable - PM me if you don't have the cable. If you aren't able to download it, a GoPro or phone camera, as someone already mentioned, works great to capture the JPI display data quickly and accurately, although it it is a bit tedious to step through each cylinder at every fuel flow increment. That's how I did it the first couple of go-arounds with the original Lycoming injectors to baseline the engine and see if GAMIs would be worth it.

The other thing I did was stay at a lower power setting than you're using, based on some Mike Busch reading I did. I use 25/2400 and 4,500 MSL. That puts your manifold pressure roughly at ambient pressure on a standard day, which Mike recommends. It also keeps your engine at a low enough power setting that just about anything you do with the mixture won't hurt the engine.

I repeated this technique through three iterations of injector swaps to ultimately get to a 0.2gph GAMI spread, as determined using the above technique. I just installed a JPI 830, and verified the same results (0.2 gph spread) with the 830 data. It can be done with patience and discipline in your data collection.

Cheers,
Rick