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Do You Need All 6 EGT's??

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DaveG601XL

Joined: 27 Oct 2006
Posts: 351
Location: Cincinnati, Oh

Posted: Tue Jan 22, 2008 1:31 pm Post subject: Do You Need All 6 EGT's??

I am still working on my Jabiru 3300/Zenith 601XL FWF and have this to throw out to you all for opinions?



 Do you really need to drill all six exhaust pipes and read six EGT's if using the Bing carb??  



I understand that you cannot tune individual cylinders with this carb set-up.  You can only change jet sizes to modify overall mixture or tilt the carb to favor one side or another.  This said, Pete's recommendation from Jabiru USA is to still go ahead and drill all six.  



I do not mind the work of drilling the extra four holes.  My concern is of creating four more potential sources of undercowl heat and carbon monoxide from possible leaks.  Maybe this is a non-issue, I don't know.  Also I know that more thermocouples increases the chances of a bad sensor making you think there is a problem where none exists.



Can anybody with real world experience of reading all six cylinders chime in with:  



1. Have you found any evidence where these probes leaked and caused issues.  

2. Did reading all six EGT's tell you something that you would not have found out by reading only two.



Pete, these are the follow-up questions that I did not think to ask when I first asked you about this at the FWF seminar last fall.



Thanks,

_________________
David Gallagher
Cincinnati, OH area

Wayne Lenox

Joined: 07 Jan 2008
Posts: 75
Location: Arizona in the winter

Posted: Tue Jan 22, 2008 2:05 pm Post subject: Do You Need All 6 EGT's??

Dave 

Yes you need all six EGT'S.  If you have one bad plug, it is easy to find with mag check.  One cylinder will go cold.  You cannot tune individual cylinders with this carb set-up, but sure can tell if one is leaner then the others and need attention. 

I have run six cylinder EGT'S on my C-182 for years and would not do with out them.  I have found they seal up very well, no leaks.  I do check that the clamps on the EGT censers are tight at each oil change.  You need all six!! 

Wayne



-- "DaveG601XL" <david.m.gallagher(at)ge.com> wrote:

--> JabiruEngine-List message posted by: "DaveG601XL" <david.m.gallagher(at)ge.com>



I am still working on my Jabiru 3300/Zenith 601XL FWF and have this to throw out to you all for opinions?



Do you really need to drill all six exhaust pipes and read six EGT's if using the Bing carb??  



I understand that you cannot tune individual cylinders with this carb set-up.  You can only change jet sizes to modify overall mixture or tilt the carb to favor one side or another.  This said, Pete's recommendation from Jabiru USA is to still go ahead and drill all six.  



I do not mind the work of drilling the extra four holes.  My concern is of creating four more potential sources of undercowl heat and carbon monoxide from possible leaks.  Maybe this is a non-issue, I don't know.  Also I know that more thermocouples increases the chances of a bad sensor making you think there is a problem where none exists.



Can anybody with real world experience of reading all six cylinders chime in with:  



1. Have you found any evidence where these probes leaked and caused issues.  

2. Did reading all six EGT's tell you something that you would not have found out by reading only two.



Pete, these are the follow-up questions that I did not think to ask when I first asked you about this at the FWF seminar last fall.



Thanks,



--------

David Gallagher

601 XL, tail and wings completed,

fueslage almost done. Working engine and electrical systems.





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p================================================================================================;         - MATRONICS WEB F================================================nbsp;                       &================================================

 



_____________________________________________________________

Need cash? Click to get a loan.

   [quote][b]

lbmathias(at)verizon.net
Guest

Posted: Tue Jan 22, 2008 2:21 pm Post subject: Do You Need All 6 EGT's??

Dave,



      I have all 6 EGT's and CHT's on my 3300 in a Lightning; the 

comparisons for all 6 have been invaluable in troubleshooting and resolving 

some CHT overheating problems through the past summer.  I am still having 

some fairly large discrepancies between the EGT's on the left and right 

sides of the engine during climbout; still working to resolve those.   Both 

rejetting and twisting the carb helped a little but I was unable to twist it 

far enough to resolve the problem because the second twist caused a blockage 

of the throttle linkage.  I may have to rejet again but having the #s for 

all cylinders helps JabiruUSA/Arion know how to advise me.



                                              Linda Mathias



  ---

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Tue Jan 22, 2008 3:31 pm Post subject: Do You Need All 6 EGT's??

Dave

Good questions I think Dave. I went through the same logic, but also each of

my probes cost AUD60 and the leads are AUD50. I worked with two probes and

the Bing and confirmed that #5 (RHS) was a good deal hotter than #6 (LHS)

which can be cured by tilting the carb. I also found the mixture excessively

rich above 2800rpm and this tends to lessen the heat differential at the

expense of power. The needle valve seat leaks from about 2800RPM up. 

I have since fitted EFI using a single throttle body with two injectors,

which mounts into the Bing spigot hose.

The additional airflow has made the problem worse and the difference in T

becomes very high above 2800RPM. I can cure the T differential problem only

by running excessively rich at the cost of power.

I believe the cause of the problem is due to the fact that the intake

headers are fed from a collector of less than 1/2L capacity. The carb feeds

the collector. A very neat and economical manufacturing design at the

expense of uniform distribution of the fuel air mix.

Good design (for EFI) demands a manifold of at least 3L capacity and I am

starting a project to make it happen for my installation.

Peter H



--

info(at)usjabiru.com
Guest

Posted: Tue Jan 22, 2008 3:35 pm Post subject: Do You Need All 6 EGT's??

We don't find any issues with the probes leaking.  Once in a while we see an

oddly lean cylinder which may indicate an intake leak.



Pete

--

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Tue Jan 22, 2008 3:41 pm Post subject: Do You Need All 6 EGT's??

Linda,

Can you advise please, what is a typical pattern of EGT ie are the RHS

hotter but even or do they also vary , and by how much. Are the LHS even and

cooler?

Thanks

Peter H



--

imap8ntr(at)aol.com
Guest

Posted: Tue Jan 22, 2008 4:38 pm Post subject: Do You Need All 6 EGT's??

Please update my profile to change my email address.  I tried to do it 

online but I forgot my name and/or password.  My new email address is 

IMAP8NTR(at)COX.NET



Thanks

Ivan



---

Kayberg(at)aol.com
Guest

Posted: Tue Jan 22, 2008 5:09 pm Post subject: Do You Need All 6 EGT's??

In a message dated 1/22/2008 4:35:38 P.M. Eastern Standard Time,  david.m.gallagher(at)ge.com writes:

  	  Quote: 	
		  Do you    really need to drill all six exhaust pipes and read six EGT's if using the    Bing carb??  

	


 

 No you dont.

  

 but it also depends on what you are using to monitor them.  If you are  looking at 6 numbers, I find that distracting.  If you have a graphic  representation, that is better.   

  

 If you notice one exhaust is higher than the others, can you do anything  about it?  Not really. But it will give you something to worry about on  long cross countries.  You can try flying along sideways to see if you can  even the flow through the carb!!!

  

 CHTs are a different matter.  You need all 6.

  

 Just my opinion.   

  

 Doug Koenigsberg

  

  



Start the year off right.  Easy ways to stay in shape in the new year. 

  [quote][b]

lbmathias(at)verizon.net
Guest

Posted: Tue Jan 22, 2008 6:48 pm Post subject: Do You Need All 6 EGT's??

Peter,



      The biggest discrepancy occurs during climbout at full power; #3 and 

#5 cylinder are generally in the high 1300's or even sometimes in the 1400's 

while #4 and #6 are registering about 1130-1150.   Nos. 1 and 2 are usually 

in the low 1300's.



      Linda



  ---

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Tue Jan 22, 2008 8:53 pm Post subject: Do You Need All 6 EGT's??

Linda,Thanks

I have seen similar EGT variance and up to 145degC difference above 2800rpm.

I get different results depending on RPM and I believe it is due to

turbulence in the collector I referred earlier. 

Peter



--

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Wed Jan 23, 2008 3:12 am Post subject: Do You Need All 6 EGT's??

I'll jump in here with couple of numbers from my 2200....At about  

2750 rpm, the left front would read 1390 and the LR 1330. When I went  

to 2850, they would almost swap readings to within a few degrees of  

the original readings. The right side would do something similar, but  

I didn't take real good mental notes of that side. All temps are of  

course F, and this was flown during an OAT of about 20 F.

I'm real glad I have all four cylinders monitored, and if I had the  

3300, I'd want them all monitored as well.



Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/460+ hrs

On Jan 22, 2008, at 11:48 PM, Peter Harris wrote:



[quote] 

 <peterjfharris(at)bigpond.com>



 Linda,Thanks

 I have seen similar EGT variance and up to 145degC difference above  

 2800rpm.

 I get different results depending on RPM and I believe it is due to

 turbulence in the collector I referred earlier.

 Peter



 --

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

DaveG601XL

Joined: 27 Oct 2006
Posts: 351
Location: Cincinnati, Oh

Posted: Wed Jan 23, 2008 4:24 am Post subject: Re: Do You Need All 6 EGT's??

OK, you convinced me.  I was leaning towards reading all six anyway.  My background is in production aircraft where I do not have every EGT and CHT looking me in the face.  In the case of the 1946 Champ I rent out, there are none.  As Doug said, why not have something else to worry about during cross country trips.



I will use the latest Jabiru recommendation of 120mm down from the face of the exhaust port.



Thanks,

_________________
David Gallagher
Cincinnati, OH area

dredmoody(at)cox.net
Guest

Posted: Wed Jan 23, 2008 6:30 am Post subject: Do You Need All 6 EGT's??

The key word on the 1946 Champ was "rent". 



Dred



---- DaveG601XL <david.m.gallagher(at)ge.com> wrote: 

 	  Quote: 	
		   

 

 OK, you convinced me.  I was leaning towards reading all six anyway.  My background is in production aircraft where I do not have every EGT and CHT looking me in the face.  In the case of the 1946 Champ I rent out, there are none.

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Jan 23, 2008 8:50 am Post subject: Do You Need All 6 EGT's??

If you have one cylinder start to run lean, for whatever reason, and you

have an electronic engine monitor then you may as well take advantage of it.

It could save you blowing a hole in a piston of a hot cylinder.



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Wed Jan 23, 2008 11:00 am Post subject: Do You Need All 6 EGT's??

Nice to see a familiar name over here, Noel...thinking of making the  

switch?  : )



Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/460+ hrs

do not archive

On Jan 23, 2008, at 11:47 AM, Noel Loveys wrote:



 	  Quote: 	
		   

 <noelloveys(at)yahoo.ca>



 If you have one cylinder start to run lean, for whatever reason,  

 and you

 have an electronic engine monitor then you may as well take  

 advantage of it.

 It could save you blowing a hole in a piston of a hot cylinder.



 Noel

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Kayberg(at)aol.com
Guest

Posted: Wed Jan 23, 2008 11:57 am Post subject: Do You Need All 6 EGT's??

In a message dated 1/23/2008 11:51:26 A.M. Eastern Standard Time,  noelloveys(at)yahoo.ca writes:

  	  Quote: 	
		  

If    you have one cylinder start to run lean, for whatever reason, and you

have    an electronic engine monitor then you may as well take advantage of it.

It    could save you blowing a hole in a piston of a hot    cylinder.



Noel

	


 

 And do what?

  

 Most likely if you have a cylinder that shows a high EGT, the probe has  gone bad, If the manifold has no leaks.  AND if you drilled the hole in the  exhaust EXACTLY the same distance as all the others.

  

 You could then swap the probe with another one to see if it is the  probe.  Other than that, it just gives you something to fret about.

  

 Keep the mixtures rich rather than lean (remember aircooled engines are  also fuel-cooled) and spend the extra $.50 an hour it costs for a slightly  rich mixture for peace of mind.

  

 I deal with electronic sensors most every day.   They are capable  of offering more information than can be processed and are difficult to check  for accuracy.   Particularly digital readouts are difficult to  asses.  EGT probes suffer a lot of temperature changes.

  

 Again, I advocate worrying about the Cylinder Head Temps on individual  cylinders more than the EGTs on each.

  

 Doug Koenigsberg



Start the year off right.  Easy ways to stay in shape in the new year. 

  [quote][b]

BobsV35B(at)aol.com
Guest

Posted: Wed Jan 23, 2008 12:35 pm Post subject: Do You Need All 6 EGT's??

Good Afternoon Doug,

  

 You ask: "And do what?"

  

 What to do is not something that can be answered with a single flip statement.

  

 Operating an engine monitor properly requires a considerable amount of study of the combustion process. The existence of a high EGT is, as you infer, relatively insignificant, but by looking for the peak EGT points, the adequacy of mixture distribution can be evaluated. The peak point can be determined accurately even when the gauge is very inaccurate!

  

 That knowledge will allow an operator to search for an answer that may provide better operating conditions. It would be nice to be able to adjust the fuel flow to each individual cylinder, but there are a multitude of other conditions that can lead to an uneven fuel mixture.  Burning up a little extra fuel may or may not be a financial disadvantage for some folks, but extra fuel is almost l always a detriment to long life in any engine.

  

 I do take strong exception to your statement that  "aircooled engines are also fuel-cooled"

  

 Extra fuel is often used to aid in placing the peak combustion event at a point where peak cylinder pressures and peak cylinder temperatures can be held within reason, but that effect can be used for engines that are cooled in any manner, not just aircooled engines.

  

 Most aircraft engines use a very rich mixture at high powers. Those same engines will run cleaner and cooler at cruise powers if they are operated at mixtures that are more lean than the stoichiometric mixture.

  

 Not only is the engine cooler and less expensive to operate when on the "lean" side, but it also produces much less carbon monoxide. While none of us ever expect to have an exhaust leak that will find it's way into our cabin heater, running lean could save your life if a leak does occur.

  

 I think there are at least two questions here. 

  

 1. Is it a good idea to find out what IS happening in each cylinder?

  

 2. Is it a good ideas to operate on the Green (lean) side of best power?

  

 I believe the answer to both questions is a strong and resounding YES!!

  

 Happy Skies,

  

 Old Bob

 AKA

 Bob Siegfried

 Stearman N3977A

 Downers Grove, IL 



  

 In a message dated 1/23/2008 1:58:28 PM Central Standard Time, Kayberg(at)aol.com writes:

  	  Quote: 	
		   And do what?

  

 Most likely if you have a cylinder that shows a high EGT, the probe has gone bad, If the manifold has no leaks.  AND if you drilled the hole in the exhaust EXACTLY the same distance as all the others.

  

 You could then swap the probe with another one to see if it is the probe.  Other than that, it just gives you something to fret about.

  

 Keep the mixtures rich rather than lean (remember aircooled engines are also fuel-cooled) and spend the extra $.50 an hour it costs for a slightly rich mixture for peace of mind.

  

 I deal with electronic sensors most every day.   They are capable of offering more information than can be processed and are difficult to check for accuracy.   Particularly digital readouts are difficult to asses.  EGT probes suffer a lot of temperature changes.

  

 Again, I advocate worrying about the Cylinder Head Temps on individual cylinders more than the EGTs on each.

  

 Doug Koenigsberg

	




Start the year off right.  Easy ways to stay in shape in the new year. 

  [quote][b]

N1BZRich(at)aol.com
Guest

Posted: Wed Jan 23, 2008 1:34 pm Post subject: Do You Need All 6 EGT's??

Hey Bob,

     What's the latest news and progress on your  granddaughter's Legend Cub?  Do she still plan on using a Jabiru  3300.  I think she will like the performance that it will provide.   See you at SNF?

 Blue Skies,

 Buz



Start the year off right.  Easy ways to stay in shape in the new year. 

  [quote][b]

BobsV35B(at)aol.com
Guest

Posted: Wed Jan 23, 2008 1:52 pm Post subject: Do You Need All 6 EGT's??

Good Afternoon Buz,

  

 They have it covered and assembled, but the engine (it is a 3300) has not yet been hung and the wiring has yet to be started. They hope to have it flying by spring break, but you know the old saying: Ninety percent finished and ninety percent to go!

  

 Happy Skies,

  

 Old Bob



  

 In a message dated 1/23/2008 3:36:38 PM Central Standard Time, N1BZRich(at)aol.com writes:

  	  Quote: 	
		   Hey Bob,

     What's the latest news and progress on your granddaughter's Legend Cub?  Do she still plan on using a Jabiru 3300.  I think she will like the performance that it will provide.  See you at SNF?

 Blue Skies,

 Buz

	




Start the year off right.  Easy ways to stay in shape in the new year. 

  [quote][b]

Kayberg(at)aol.com
Guest

Posted: Wed Jan 23, 2008 2:39 pm Post subject: Do You Need All 6 EGT's??

In a message dated 1/23/2008 3:38:05 P.M. Eastern Standard Time,  BobsV35B(at)aol.com writes:

  	  Quote: 	
		     Good Afternoon Doug,

    

   You ask: "And do what?"

    

   What to do is not something that can be answered with a single flip    statement.

    

   Operating an engine monitor properly requires a considerable amount of    study of the combustion process. The existence of a high EGT is, as you infer,    relatively insignificant, but by looking for the peak EGT points, the adequacy    of mixture distribution can be evaluated. The peak point can be determined    accurately even when the gauge is very inaccurate!

    

   That knowledge will allow an operator to search for an answer that    may provide better operating conditions. It would be nice to be able to adjust    the fuel flow to each individual cylinder, but there are a multitude of other    conditions that can lead to an uneven fuel mixture.  Burning up a little    extra fuel may or may not be a financial disadvantage for some folks, but    extra fuel is almost l always a detriment to long life in any engine.

    

   I do take strong exception to your statement that  "aircooled    engines are also fuel-cooled"

    

   Extra fuel is often used to aid in placing the peak combustion event at a    point where peak cylinder pressures and peak cylinder temperatures can be held    within reason, but that effect can be used for engines that are cooled in any    manner, not just aircooled engines.

    

   Most aircraft engines use a very rich mixture at high powers. Those same    engines will run cleaner and cooler at cruise powers if they are operated at    mixtures that are more lean than the stoichiometric mixture.

    

   Not only is the engine cooler and less expensive to operate when on the    "lean" side, but it also produces much less carbon monoxide. While none of us    ever expect to have an exhaust leak that will find it's way into our cabin    heater, running lean could save your life if a leak does occur.

    

   I think there are at least two questions here. 

    

   1. Is it a good idea to find out what IS happening in each  cylinder?

    

   2. Is it a good ideas to operate on the Green (lean) side of best    power?

    

   I believe the answer to both questions is a strong and resounding    YES!!

	


 

  

 I do plead guilty to being flip.  But I think you missed my  point.

  

 With a single carb for 6 cylinders, that is altitude compensating not  mechanically leanable from the cockpit, just what options does the worried pilot  have?

  

 True you can get some indication of what is happening in each cylinder, IF  the sensors are correctly placed and monitored, IF you have both EGT and CHT  probes , you MAY have a means of understanding what MAY be happening.  That  takes some resounding off the yes to question one.

  

 While it may be a good idea to operate on the lean side of peak, just how  do you do that when you have little control over it?  The carb supplied  with the Jab 3300 can be tweeked to run lean at a particular altitude,  particular load and particular RPM.  But it will make up its own mind at  all other throttle settings, density altitude and load.   That takes a  great deal of shine off the resounding Yes to question 2.

  

 I thought that fuel cooling was well known in the aviation engine business,  perhaps I am wrong.  I remember reading a couple articles about it over the  years.  But it is particularly helpful in high power settings, such as  takeoff and climb....which is why many engines do run rich at those  settings.  Not so helpful at cruise, I agree.

  

 I do agree that knowing Peak EGT would be very helpful IF you could control  the mixture.

  

 No quibles about carbon monoxide being less at lean mixtures.   However, a tight cockpit is a requrement if you are going to get gassed.....and  requires use of a cabin heater with access to combustion products.

  

 Doug Koenigsberg



Start the year off right.  Easy ways to stay in shape in the new year. 

  [quote][b]

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