Can I fly LOP without GAMI's

[Glen Davis]

I've attached a picture of my panel so you can see what gauges I have and don't have. In short, I have an EDM 700, a digital tach, a JPI 450 for digital fuel flow and a manual MP gauge.  I do not have GAMI's.  This is in an 84 J model.  Can I expect to fly LOP accurately and consistently with this setup but without GAMI's?  If so, what would be the procedure to do so? How much does it cost to buy and have GAMI's installed?

Thanks.

Glen  PS: I pick up my new-to-me J on Thursday!!

[1964-M20E]

Sure all you really need is accurate fuel flow, and all 4 EGTs.  You can also do it with only one EGT and fuel flow.  The newest most sophisticated instruments will tell you how far ROP or LOP you are running.

 

Now on the other hand you will get many opinions of running LOP vs ROP but that is another topic entirely.

 

 

[HIghpockets]

Two good sources of information about LOP ops, in my opinion, are the Advanced Pilot Seminars ( John Deacon et al) that you can find online and reading Mike Busch's book "Engines". Congrats on the purchase. I fly a 88J with a JPI 700. I don't have Gami injectors and I fly LOP.

[Bartman]

The short answer is yes and I do it on every flight with my 1977 J with the same engine as you have and JPI-700 monitor. If you have used that monitor before then great, but if not then download the manual and become familiar with setting it up to run LOP. Pick a power setting in your POH that is 65% HP and set it there to start. Use the procedure in the manual and remember to move the mixture very slowly. The main thing is you get ALL four cylinders LOP and if you are new to it I would just shoot for 15-20 LOP and as long as she is running smooth then you cannot hurt anything. 
 

Quick calculation (14.9 x fuel flow) / 200 = % HP while LOP. Anything under 65% you won’t hurt anything. 
If you start at 65% ROP then you will be less than that when you adjust mixture to LOP. 

Edited September 20, 2020 by Bartman

[Cruiser]

the 1984 M20J is one of the most economical Mooneys ever made. You should consistently see 15 mpg at 150KTAS. 

Yes, you can fly LOP with your setup. BUT I would suggest you sell the 450 and use the money to upgrade the 700 to an 830

If you have not done this yet, you should go up on a clear smooth day to 7000 MSL. Set the power and RPM to cruise, engage the autopilot and let the plane settle into cruise. Note, Airspeed, FF and EGT,

1. start leaning slowly. watch the EGTs and notice the first cylinder to reach peak EGT.

2. record the cylinders as they peak the EGT temp and the FF when they do. Remember, lean slowly. 

3. They will all be very, very close. IF you can get a copilot to help with recording the data that would be easier.

4. Don't worry at the temp, go slowly, at 7000' you cannot do anything bad to the engine. keep leaning until all four cylinders reach peak and start to decrease EGT.

Your are flying LOP and you just did a GAMI spread.  

Let us know your results. 

[Schllc]

I would budget 1500 for the gami’s which would include purchasing, replacing and tuning one additional set after the first. 
I had to go through five sets of injectors before I hit paydirt. 
but my fuel flows at cruise went down over 3gph at the same speeds. 
that being said, I had a tsio550 and one of the worst spreads gami said they had seen, so it was a bit of an outlier. 
however, the fuel you save will more than pay for the injectors if your spread is bad. 
you can document your procedure and send to gami and they will tell you if you need them. I have had them tell me on other planes the improvement wouldn’t be worth the money. 
they are a really good company to deal with, and know their business. 

[Bob - S50]

As others have said, yes you will most likely be able to run LOP without GAMI injectors.  We do in our '78 J.

[GeeBee]

You need good injectors, but you also need a strong ignition. Do not forget the ignition component. LOP is impossible with weak mags.

For Continental, I was surprised to find that the factory tunes the injectors during the test cell run. They are indeed different for each cylinder.

 

 

 

[McMooney]

Yes, LOP existed before engine monitors and Gami injectors.

[kortopates]

41 minutes ago, GeeBee said:

You need good injectors, but you also need a strong ignition. Do not forget the ignition component. LOP is impossible with weak mags.

For Continental, I was surprised to find that the factory tunes the injectors during the test cell run. They are indeed different for each cylinder.

Excellent point on ignition - most people forget about how important ignition is and running LOP put much greater stress on the ignition - it must be in very good shape

Not exactly on the Continental tuned injectors. Continental position tuned injectors are not tuned to the individual engine but to the model engine. Unlike Gami's who do tune the injectors to your individual engine cylinders, TCM provides one and only sized injector for each cylinder that legally can only be installed in the specific cylinder. They're not know for getting gami spreads below 0.5 GPH but typically provide 0.5-0.7 GPH spreads - which often is good enough if one doesn't run too deeply LOP.

[kortopates]

3 minutes ago, McMooney said:

Yes, LOP existed before engine monitors and Gami injectors.

Yes, it dates back to big radial engines where we had someone dedicated to managing the engines in flight - which has absolutely nothing to do with the ability to run any specific engine LOP!

[kortopates]

I've attached a picture of my panel so you can see what gauges I have and don't have. In short, I have an EDM 700, a digital tach, a JPI 450 for digital fuel flow and a manual MP gauge.  I do not have GAMI's.  This is in an 84 J model.  Can I expect to fly LOP accurately and consistently with this setup but without GAMI's?  If so, what would be the procedure to do so? How much does it cost to buy and have GAMI's installed?

Thanks.

Glen  PS: I pick up my new-to-me J on Thursday!!

 

Very few J's need Gami's but you really do need integrated engine monitors with FF. You can either upgrade/Add the FF sensor to your JPI 730 so that FF is logged with your EGTs - which essential to measuring your gami spread. Or you can upgrade your 730 to 830 which is the better option. The upgrade just replaces the head display for about 1 amu with your old 730 core credit.

Its impossible to get decent data trying to write down the FF as each cyl peaks. It really needs to come from the data dump to get repeatable accurate data. I've seen numerous clients try and their all guesses at best. The best you can do is get rankings - which is helpful but not enough. 

However, while your in this stage of limited instrumentation, its also perfectly safe to just limit yourself to 65% power and less and lean to the LOP side to start learning. At 65% and below you can't hurt the engine regardless of where you leave to mixture. Just learn first how to determine % power on the LOP side by FF alone as mentioned above. Once you have the integrated FF you can get more detailed and learn how to run at higher power settings where it becomes important to know where you are relative to the red box of high ICP's.

Edited September 20, 2020 by kortopates

[carusoam]

Summary,

1) Yes you can...

2) Read the Manual for your JPI before going in the plane...

3) leaning has some rules, 65%bhp or less for LOP, is a safe place to be while experimenting...

4) Read up on the GAMI spread... a test you can run with what you have...

5) Read up on how to download your engine’s data, load it up to savvy, post the link here...

6) Take good notes, it  is easy to do, once familiar...

7) there may be some set-up options you want to update in your JPI...

8) Four cylinder Lycomings have really good GAMI spreads naturally... although some improvement can be found by going to Gamis... if you want the tightest spread possible...
 

9) Six cylinder engines really benefit from balanced fuel injectors... because long intakes are not always well balanced...

If you get all this done... you have become your own flight engineer... 
 

PP thoughts only, not a mechanic...

Best regards,

-a-

[midlifeflyer]

Do you remember student pilot training when you leaned to engine rough and then enrichened until until smooth? That was lean of peak.

[aviatoreb]

5 hours ago, kortopates said:

Yes, it dates back to big radial engines where we had someone dedicated to managing the engines in flight - which has absolutely nothing to do with the ability to run any specific engine LOP!

I bet that guy whose job it was to operate the engines was called “the engineer”.

[GeeBee]

8 hours ago, kortopates said:

Excellent point on ignition - most people forget about how important ignition is and running LOP put much greater stress on the ignition - it must be in very good shape

Not exactly on the Continental tuned injectors. Continental position tuned injectors are not tuned to the individual engine but to the model engine. Unlike Gami's who do tune the injectors to your individual engine cylinders, TCM provides one and only sized injector for each cylinder that legally can only be installed in the specific cylinder. They're not know for getting gami spreads below 0.5 GPH but typically provide 0.5-0.7 GPH spreads - which often is good enough if one doesn't run too deeply LOP.

I would agree that they are positional and not individual runs, however, it is based upon repeatable data. The NA's are more consistent than the turbo's because the airflows in the turbos are pressure which is harder to create create repeatable data.. However all that said, my Ovation runs 0.2 gah differential which even GAMI admitted they cannot improve upon. Further it is a lot more than the competition is doing.

 

https://www.csobeech.com/files/TCM-InjectorSID05-7.pdf

 

 

[gsxrpilot]

Maybe we should start with the GAMI spread. This actually doesn't have anything to with GAMI. It's just the process of measuring your fuel flow distribution to see if it's in close balance or way out of balance. If it's way out of balance, then GAMI's are the best answer to bringing the fuel flow into balance.

Basically, to fly LOP well, you need a well balanced fuel flow distribution. Measuring the "GAMI spread" is just measuring the difference in fuel flow from your richest cylinder to your leanest cylinder. If the difference is 0.5 gal or less, you're good to go. If that difference is >0.5 gal, you might benefit from a set of GAMI injectors.

So go out and fly and measure the spread. @Cruiser gave you an excellent description of the process. 

As an example, following that procedure, if you noted the first cylinder to have it's EGT peak and start back down, to have happened at 10.2 gph, and then the next cylinder peaked, then the next, and then the final cylinder peaked at 9.8 gph, your GAMI spread is 0.4. 

SavvyAnalysis has a Flight Test Profile that is an excellent step by step procedure to determine if your engine is set up to run LOP properly. https://resources.savvyaviation.com/resources/other-documents/ Go there and get the Flight Test Profile.

So go get your GAMI spread and report back 

[Ibra]

3 hours ago, midlifeflyer said:

Do you remember student pilot training when you leaned to engine rough and then enrichened until until smooth? That was lean of peak

I wondered how that works with variable pitch?

For fixed pitch you get a feel on RPM before power drops steeply but how on variable pitch with CSU keeping constant RPM? but I do feel slight slowdown/traction even before engine runs rough/smooth 

[midlifeflyer]

14 minutes ago, Ibra said:

I wondered how that works with variable pitch?

For fixed pitch you get a feel on RPM before power drops steeply but how on variable pitch with CSU keeping constant RPM? but I do feel slight slowdown/traction even before engine runs rough/smooth 

Dunno. But FWIW, I've used the method in airplanes with constant speed props too. Engine mechanics is not my strong suit, but as far as I can tell, starving the engine still produces roughness, whether it be a substantial RPM drop or something less but still detectable.  

Most of the time, it's an airplane with an old fashioned single EGT but I've done a comparison out of curiosity in a few which have more extensive instrumentation, including G1000s with lean assist. Hardly a scientific sample but I haven't seen a huge difference. Similar EGT, similar fuel flow, and similar cool CHTs. Obviously not the same accuracy as nailing 20 degrees LOP on the last cylinder to peak, of course.

 

[gsxrpilot]

I don't feel the power drop going to LOP as much as I feel the power surge when coming back to the rich side. Coming back rich, it is quite pronounced.

The only problem I see with using roughness as the gauge is that unless you know the "GAMI spread" you don't really know where the roughness occurs. If the GAMI spread is a gallon or or more, the roughness might be occurring at peak. And at a high power setting, that could be the worst place to run. Conversely in an engine with a .2 GAMI spread, you probably won't ever find the roughness. The engine will run smooth all the way to idle cut off.

It really depends on the fuel flow balance between the cylinders.

[jaylw314]

Most Lycoming IO-360's have pretty good injector balance.  My rebuilt IO-360 came with a GAMI spread of 0.4, so I've not bothered with GAMIjectors.

If not done already, double check that the FF sensor isn't already hooked up to the EDM-700.  There's an option to do that if the sensor goes through a FP-5L, so I wonder if that's kosher with the JPI 450.  Adding the FF option to the EDM-700 is pretty inexpensive anyway (about $500, IIRC)

Edit: I checked the JPI website, they list "Fuel Flow Electronics option for EDM-700/730’s, functions with any digital transducer" for $195

Edited September 21, 2020 by jaylw314

[PT20J]

Don't make this complicated.

The injectors aren't the issue -- it's the terrible induction system design of most Continentals that prevent running LOP without GAMI injectors. Radials run LOP easily with -gasp- carburetors. Lycoming's 4 bangers have pretty well tuned induction systems. Piper included a LOP procedure in the POH for the carbureted O-320 Warrior (I've posted it previously). If everything is working correctly, an M20J should run LOP without any modifications.

You don't even need fancy instrumentation. Lean carefully until it gets rough and richen just until it gets smooth. That's usually around 20-40F LOP depending on the power setting.

Skip

[carusoam]

When you have a nicely balanced intake system like the IO550 with Gamis...

There is no lean to rough... because the Gami spread can be 0.0 or 0.1... gph 

There is however Lean until silent...  which happens around 90°F LOP down low, or about 50°F LOP up high... at WOT...

 

The Continental six cylinder engines with the curvy, equal-length type, intake tubes, which stay balanced through a wide range of power and RPM compared to the log type intake manifolds...

The magic of four cylinder Lycomings... the intake tubes are identical in length... naturally... get a good look at a pic of the actual intake... to see where the differences of airflow can occur, from air filter to throttle plate to intake tubes...

So... get to altitude where 65%bhp is only available, and lean slowly to capture all the data...

get used to the engine monitor, the raw EGTs, the MP and FF range... and Gami spread!
 

PP thoughts only, not a mechanic...

Best regards,

-a-

[PT20J]

23 hours ago, jaylw314 said:

Edit: I checked the JPI website, they list "Fuel Flow Electronics option for EDM-700/730’s, functions with any digital transducer" for $195

I just did this with my EDM 700. For $195 you get the modification and the wiring harness -- no transducer. The harness lets you piggy back the transducer signal from wherever it is currently connected (mine is connected to a Shadin Miniflo-L) and also lets you input GPS data to the EDM for range calculations. The harness includes a three position toggle switch to allow the EDM 700 to display EGT (normal mode without fuel flow), FF (fuel flow related) or ALL data.

Skip

[jaylw314]

1 minute ago, PT20J said:

I just did this with my EDN 700. For $195 you get the modification and the wiring harness -- no transducer. The harness lets you piggy back the transducer signal from wherever it is currently connected (mine is connected to a Shadin Miniflo-L) and also lets you input GPS data to the EDM for range calculations. The harness includes a three position toggle switch to allow the EDM 700 to display EGT (normal mode without fuel flow), FF (fuel flow related) or ALL data.

Skip

I guessed I figured OP already has a digital transducer since he has the JPI 450 installed.  I had previously assumed the option was only available for some transducer models, but they make it sound like it'd do for any model transducer.