Jump to content

leaning for power


Hugo

Recommended Posts

4 hours ago, Hugo said:

What egt and cht numbers are normal for leaning rich of peak?

Here's what the Sun Visor had on the M20M and what was in the POH.

MOONEY M20M POWER SCHEDULE.pdf

 

Later on, Lycoming, Mooney and M20M pilots came to realize that Turbine Inlet Temps over 1650 degrees F would dramatically reduce cylinder, turbo and exhaust system life, whether the engine had the Bravo (wet head) conversion or not.

Link to comment
Share on other sites

See if this opens up some ideas...then ask the question with more detail.

When using an Ovation, the POH gives guidance for both ROP and LOP. If you have the 310hp STC, the Stc has additional guidance....

1) become familiar with the blue box on the ship's EGT gauge, white box if you have a G1000.

2) In most planes the Chts are installed after leaving the factory adding to the variation.

3) CHTs.  Are very dependent on power setting an OAT. There are no O cowl flaps.  Location, as in distance from the exhaust valve plays a large role.

4) usual guidance for CHTs.... keep them under 380°F when possible. Best cylinder health is cool.

5) what engine do you have? What max rpm are you using? There is a max FF that you should be getting. 25 gph to over 30gph...

6) the Ships EGT gauge is the one used for power settings. The blue box is used for climbing ROP.

7) Peak is where you find it, on your machine, on this day... weather and altitude dependent.

8) ROP is richer than where you found peak.

9) I made a few assumptions like, Hugo is flying an O.  His O's ship's EGT gauge has a blue box. He knows how to find the peak while leaning....

10) I'm hoping this is helpful. I am only a PP trying to learn about flying... :)

 

Hugo,

Please ask the question with as much detail as you can.  These fine gentlemen here can answer better, once you have supplied the proper details...

Take a moment to add some detail to your avatar.  Location can be pretty helpful.

 

Best regards,

-a-

Edited by carusoam
Link to comment
Share on other sites

Hugo,

You got a lot of good advice in this thread, both about EGTs as well as the spot on advice by Kmyfm20's  to check you max takeoff FF from as near sea level as you can. That is the first thing to check if you think your EGTs are high, as in excessively lean. But you never responded after you started the thread - instead you started another thread with a more general question? Lots of people willing to help here if you're willing to participate. FWIW, I can tell you are a very experienced pilot but without an exchange I don't know where to begin....

 

Edited by kortopates
  • Like 1
Link to comment
Share on other sites

Thanks for the reply. kortopates.  I am presently looking at anywhere between 50-80 differential between coolest and honest egts.  I believe I may have an injector that needs tuning or changing out.  The first time out I had an 80 degree spread and the last time 50, so it is improving. I was just wondering what people were looking at when leaned out at curse.

 

 

Link to comment
Share on other sites

Hugo,

The IO550 has curvy intake pipes to balance the air flow to each cylinder.  The fuel injectors from Continental are pretty good too. 

At about 5000’ AGL, leaning the engine during cruise @65% power, the GAMI spread can be near 0.  The engine will run about 80°F LOP before the mixture gets too lean to run. Then the engine quits...

From what is being described. There is probably either an injector issue or an air leak issue...

Since absolute EGTs are not often usable for diagnosis, use the Gami spread technique to determine  how well balanced the FF is in the FIs.

A blocked fuel injector will peak before the others, along with showing a variation in temperature.

PP thoughts only.  Not a mechanic.

Best regards,

-a-

Nice photos Lance, he caught all six EGT and Chts as indicated by the dot under the cylinder number. The TIT number is there because Lance is driving a TLS now?

Edited by carusoam
Link to comment
Share on other sites

Thanks for the reply. kortopates.  I am presently looking at anywhere between 50-80 differential between coolest and honest egts.  I believe I may have an injector that needs tuning or changing out.  The first time out I had an 80 degree spread and the last time 50, so it is improving. I was just wondering what people were looking at when leaned out at curse.
 
 

Hugo, a 50F EGT spread is normal. We usually don't worry about the size of EGT spread until it's greater than 150. We'll see even larger spreads in carbureted engines. What is much more important is the tightness of the gami spread as Anthony mentions above. In other words we don't really care about absolute EGT values, what we care about is how close each of the cylinders reaches peak EGT at a given GPH. So if you were to run at approx 65% power, but no higher, and leaned till your cylinder Peaked in EGT, (this is your leanest), and say you measured that it peaked right at 10.0 GPH, then you continue to lean as each cylinder peaked EGT, till your last cyl peaked (your richest) and let's say it peaked at 9.5 GPH. This would indicate a spread of 0.5 GPH, which is exactly what you need for smooth LOP operations. If it is worse than 0.5 GPH then yes, now we want to work to improve it. But if within 0.5 that is fine. So it's not the temperatures that they peak at that we care, but how close to the same Fuel Flow that they peak.
The other thing critical to smooth LOP ops is a healthy ignition. To evaluate that, we perform a LOP Mag check in the air at approx 50F LOP and evaluate the down loaded data. If we see missing or a weak spark plug(s), we need to address the ignition system to to be able to run smoothly LOP. This is often the first thing to go when an engine stops running smoothly LOP.

For more details on how to measure your GAMI and the LOP test, I suggest opening up free account on SavvyAnalysis.com and uploading your engine data. The site has built in tools to make this easy, and tutorials on how to read your data. Or you can hire us on Savvy for professional analysis. But under "resources" you'll find step by step instructions on how to run the Savvy Test profile that does this. And go at it. But first I recommend setting you analyzer's sampling rate to 1 sec or it's fastest rate. The default of 6 sec for some is too slow.


Sent from my iPhone using Tapatalk
  • Like 1
Link to comment
Share on other sites

For Lance, I recommend running the Savvy Test profile. It is probably a spark plug or ignition issue causing roughness, but if you do both you'll have all the data needed to be sure. But first I'd look for an erratic plug or excessive rise in the LOP mag check.


Sent from my iPhone using Tapatalk

Link to comment
Share on other sites

Maybe you have this covered, but you should know that differences between absolute EGT's are pretty much irrelevant to anything.  One common reason is that when the probes were installed, an obstruction or a curve in one of the pipes caused the AP to put the probe in a different location relative to the valve opening, than the other probes.  You gotta do a lean test to see if there is a fuel flow difference that is out of line, and if they are all within .5 GPH then ignore the EGT differences.  They are not real.  They are measuring differences at the different probes.  

Link to comment
Share on other sites

On 4/26/2017 at 6:36 PM, kortopates said:

For Lance, I recommend running the Savvy Test profile. It is probably a spark plug or ignition issue causing roughness, but if you do both you'll have all the data needed to be sure. But first I'd look for an erratic plug or excessive rise in the LOP mag check.


Sent from my iPhone using Tapatalk

Also...for a Bravo...my #1 is coldest cht with my #5 #6 matching yours...your TIT is real conservative...try for 1550 or 1600.. his #1 matches #6 which is right up ft and not losing air pressure from the oil cooler above it.

Link to comment
Share on other sites

4 hours ago, thinwing said:

Also...for a Bravo...my #1 is coldest cht with my #5 #6 matching yours...your TIT is real conservative...try for 1550 or 1600.. his #1 matches #6 which is right up ft and not losing air pressure from the oil cooler above it.

Those numbers were my EGT's. My TIT was at 1602.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.