Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

CHT update

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

recapen(at)earthlink.net
Guest

Posted: Mon Nov 23, 2009 3:23 pm Post subject: CHT update

As many of you may know, I have been obsessing a bit about my CHT's...to  get them consistent.



Here's the setup:

IO360B1F6

9.2:1  pistons

AFP Fuel Injection

LASAR Ignition with CHT sender relocated to  allow for testing

Vetterman Dual Crossover Heater/Mufflers

SamJames cowl  and plenum

Advanced Flight Systems 3400 Engine Monitor



Oil Cooler  mounted behind #4 cylinder

Air for both Heater/Mufflers behind #3  cylinder



For constant power setting, here's the consistency that I have  achieved:

#1 and #3 cylinders run within three degrees (avg) of each  other

#2 and #4 cylinders run within three degrees (avg) of each other

The  #1/#3 cylinders run 8.5 degrees hotter (avg) than the #2/#4  cylinders



With the members of the sets of cylinders running this close  each other, I'm thinking that I have the balance (front to rear) for each side  pretty well matched.



I'm trying to wrap my head around what could be  causing the right side to run hotter than the left.  Here's some of what  I'm thinking...: With this plenum set-up, I'm thinking that the pressure/volume  should equalize from left to right.  This would leave me with not much to  change to cause more cooling air to go from the left to the right - meaning that  I probably have to live with the differences.  Alternatively, maybe it's  not really hotter...the two sets of CHT wires for the left side (both equal  length) are about three feet longer than the ones for the right side (again,  both equal length).  Could the difference in the lengths of the wires  account for the reported temperature difference? 



I'm pretty close to  thinking that this is as good as it gets...but I would really like to know  why...



Thanks,

Ralph

   [quote][b]

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

skywagon

Joined: 11 Feb 2006
Posts: 184

Posted: Mon Nov 23, 2009 9:29 pm Post subject: CHT update

Ralph,

 You have got to be kidding about the tiny CHT temp.  difference......!!  In the air-cooled world that is incredibly  consistent.  Just running different power settings will cause a larger  delta than what you described.  Go fly it.... you did everything  right...[img]cid:813D2BD1B06D4451BF2713C4713847F4(at)HpVistaPC[/img]

 Dave

 [quote]   ---

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

!cid_001f01c81d8e$e2fe3050$29591fd0@renenpaula.jpg

Description:

Filesize:

17.62 KB

Viewed:

3173 Time(s)

!cid_001f01c81d8e$e2fe3050$29591fd0@renenpaula.jpg

recapen(at)earthlink.net
Guest

Posted: Tue Nov 24, 2009 5:21 am Post subject: CHT update

Thanks Dave,



Looks like a pattern is emerging.



Ralph



--

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Nov 24, 2009 7:07 am Post subject: CHT update

At 11:26 PM 11/23/2009, you wrote:

  	  Quote: 	
		   Ralph,

 You have got to be kidding about the tiny CHT temp. difference......!!  In the air-cooled world that is incredibly consistent.  Just running different power settings will cause a larger delta than what you described.  Go fly it.... you did everything right...[img]cid:7.1.0.9.0.20091124085719.01d4b888(at)aeroelectric.com.1[/img] 

 Dave 	


    You beat me to it Dave. It's unusual that the casually

    installed system runs so temperature tight!  I don't know if

    G. Braley still monitors the AE-List but I'm sure he would be able

    to recite a long list of variables that affect operating

    temperatures of each cylinder. He built a business on fine

    tuning fuel injected engines for optimum performance on

    a cylinder/by/cylinder basis. To get a handle on effectiveness

    of his development efforts, he first needed to identify

    and quantify if not control variables outside his sphere of

    development. I'm sure they were plentiful.



    Ralph's installation looks like a nicely frosted cake to

    me too!



 

 

        Bob . . .



         ---------------------------------------

        ( It's MATRONICS FUND RAISER MONTH!    )

        ( Do your part to keep this marvelous  )

        ( tool sharp and available to all our  )

        ( brothers in the OBAM aviation        )

        ( community.                           )

         ---------------------------------------

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

2e0b2631.jpg

Description:

Filesize:

17.62 KB

Viewed:

3165 Time(s)

recapen(at)earthlink.net
Guest

Posted: Tue Nov 24, 2009 7:25 am Post subject: CHT update

Thanks Bob - and I take it that the wire length is not a factor...?



--

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

sportav8r(at)gmail.com
Guest

Posted: Tue Nov 24, 2009 7:48 am Post subject: CHT update

I'll be troubleshooting a sudden discrepancy in CHT's over the holidays that cropped up shortly after the day I put my new P-mags on in place of the older models - suddenly #4 is showing about 190* F when the other three are still indicating within a few degrees of each other in the 350-380 range.  EGT's are all where they've always been for all 4 cylinders, and power output, engine smoothness seem normal. 



I'm guessing a bayonet probe has been jarred loose somehow or has failed, but need to pull the cowl and have a closer look.  Between an IR thermometer to scan the cylinders, and a cup of boiling water to dunk the probe in, I hope I can determine whether the problem is with the probe and wiring, or a cylinder that's actually too cold, for whatever reason.

 



I will let the list know what I find.

Bill B. /RV-6A O-320



On Tue, Nov 24, 2009 at 10:24 AM, Ralph E. Capen <recapen(at)earthlink.net (recapen(at)earthlink.net)> wrote:

 [quote]--> AeroElectric-List message posted by: "Ralph E. Capen" <recapen(at)earthlink.net (recapen(at)earthlink.net)>

  

 

Thanks Bob - and I take it that the wire length is not a factor...?

 

 --

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Nov 24, 2009 8:36 am Post subject: CHT update

At 09:24 AM 11/24/2009, you wrote:

 	  Quote: 	
		  

<recapen(at)earthlink.net>



Thanks Bob - and I take it that the wire length is not a factor...?


	


   Probably not. CHT displays may be implemented with either

   thermocouples or some form of temperature-dependent resistance

   "sender".



   When I was working on S.E. production airplanes, the

   technology of choice was temperature-dependent resistors.

   But even these devices are relatively high resistance

   compared to the resistance of lead wires. Modern

   implementation of thermocouple to micro-controller

   allows thermocouples of any practical length without

   measurement error.



   WAAAAaayyy back when, the first thermocouple driven

   temperature displays were meter movements that read

   millivolt levels directly. Instruments of this class

   must necessarily be LOW impedance and therefore draw

   significant current. This drove designers to use FAT

   thermocouple wires of KNOWN length. Quite often, the

   instrument would include a precision calibration

   resistor on the back of the instrument so that readings

   for the outboard engines on a DC6 could be calibrated

   for the longer lead-wires as compared to the inboard

   engines.



   This FACT of legacy thermocouple technology has

   morphed over the years into a modern MYTH about

   thermocouple lead lengths. If your installation

   manual omits discussion about sensor lead lengths

   then they're not critical.

        Bob . . .



         ---------------------------------------

        ( It's MATRONICS FUND RAISER MONTH!    )

        ( Do your part to keep this marvelous  )

        ( tool sharp and available to all our  )

        ( brothers in the OBAM aviation        )

        ( community.                           )

         ---------------------------------------

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

recapen(at)earthlink.net
Guest

Posted: Tue Nov 24, 2009 8:48 am Post subject: CHT update

Thanks Bob,



Nothing about lead length that I've found.



Based on the pattern of responses, time for a coke and a smile....and go fly!



Ralph



--

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Speedy11(at)aol.com
Guest

Posted: Wed Nov 25, 2009 12:21 pm Post subject: CHT update

Bill,

 There are lots of possibilities with your situation, but a loose probe  would be the likely cause.

 Are you running the P-Mags with the manifold pressure adjusted  timing?  Are you using auto spark plugs?  Did you check  the wiring resistance for the #4 cylinder?  Are the plugs gapped  correctly?

 It's puzzling that one cylinder would drop that much.

 Stan Sutterfield

 Do not archive

  	  Quote: 	
		  I'll be    troubleshooting a sudden discrepancy in CHT's over the holidays    that

cropped up shortly after the day I put my new P-mags on in place of    the

older models - suddenly #4 is showing about 190* F when the other three    are

still indicating within a few degrees of each other in the 350-380    range.

EGT's are all where they've always been for all 4 cylinders, and    power

output, engine smoothness seem normal.



I'm guessing a bayonet    probe has been jarred loose somehow or has failed,

but need to pull the    cowl and have a closer look.  Between an IR thermometer

to scan the    cylinders, and a cup of boiling water to dunk the probe in, I

hope I can    determine whether the problem is with the probe and wiring, or a

cylinder    that's actually too cold, for whatever reason.



I will let the list know    what I find.



Bill B. /RV-6A O-320 	


 

  

  [quote][b]

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum