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CHT update

 
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recapen(at)earthlink.net
Guest
PostPosted: Mon Nov 23, 2009 3:23 pm    Post subject: CHT update Reply with quote
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
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chaskuss(at)yahoo.com
Guest
PostPosted: Mon Nov 23, 2009 3:59 pm    Post subject: CHT update Reply with quote
Ralph,
Have you installed an AN960 washer between the rear baffle & cylinder head on the #3 cylinder? The #2 & #3 cylinders have very thin fins between the head itself and the [front on #2] rear baffle. By installing a single washer between the above mentioned parts, for the bolt that holds the rear baffle onto #3, you will reduce the temp on #3. You will then have to cut down the air dam in front of #1 to even out that side. This should help to reduce the side to side variation you have. See

http://www.vansairforce.com/community/showpost.php?p=31012&postcount=40

Charlie Kuss

--- On Mon, 11/23/09, Ralph E. Capen <recapen(at)earthlink.net> wrote:

Quote:
From: Ralph E. Capen <recapen(at)earthlink.net>
Subject: CHT update
To: rv-list(at)matronics.com, LycomingEngines-list(at)matronics.com, AeroElectric-list(at)matronics.com
Date: Monday, November 23, 2009, 6:22 PM







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






provided




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robin1(at)mrmoisture.com
Guest
PostPosted: Mon Nov 23, 2009 4:04 pm    Post subject: CHT update Reply with quote
Ralph,
  As one who has been perplexed by temperatures (RV-10, James Cowl, Plenum etc…) I would sleep quite well at night with your numbers. If you are looking for reasons why one bank is different that the other you can consider the oil cooler asymmetry or prop rotation or maybe some differences on the lower portion of the fire wall forward making exit air asymmetrical or you can put some of this on the sensors ability to resolve these very small differences in relative temperature. As far as the “pressure volume equalizing left to right” maybe yes, maybe no. I suspect proving this may be very difficult w/o extensive R&D for what benefit? Cutting the difference in half so you are within 4 degrees left/right. I tend to think of the air under the Cowl/Plenum as a frantic tumbling & crashing of molecules with a large amount of air reversing course and exiting out the front of the cowl. It is not a smooth aerodynamic “flow through” environment under the hood. I think even with your numbers you can retain bragging rights over 99% of aircraft flying today.
An alternative solution is to revert back to a single CHT/EGT probe and consider them all the same. Wa-la perfect balance! EFIS = Eliminate Further Ignorance Systems

Well done,
Robin

From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of Ralph E. Capen
Sent: Monday, November 23, 2009 3:23 PM
To: rv-list(at)matronics.com; LycomingEngines-list(at)matronics.com; AeroElectric-list(at)matronics.com
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
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www.aeroelectric.com
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carl.froehlich(at)verizon
Guest
PostPosted: Mon Nov 23, 2009 4:36 pm    Post subject: CHT update Reply with quote
I’d guess you are well be within the accuracy of the temperature probes themselves. In other words, you are way close enough.

Carl Froehlich
RV-8A (500 hrs)
RV-10 (installing systems)

From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of Ralph E. Capen
Sent: Monday, November 23, 2009 6:23 PM
To: rv-list(at)matronics.com; LycomingEngines-list(at)matronics.com; AeroElectric-list(at)matronics.com
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
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[quote][b]

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Kellym



Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
PostPosted: Mon Nov 23, 2009 4:54 pm    Post subject: CHT update Reply with quote
If your end results are all cylinders staying below 400 in climb and
preferably below 380, your balance between cylinders, both front to rear
and side to side is more than adequate. As for reasons the right side
is hotter, it is last in the oil delivery plumbing, so the lifters and
rocker boxes get about 1/2 what the left side gets. Most Lycomings have
#2 and #3 run hottest because of too tight cowling in front of #2 and
behind #3, where there are no fins on the intake side of head, so only
with a little spacing, perhaps 1/8" will you get airflow over that side
of the cylinder. The spacer is worth about 30 degrees cooler.

Ralph E. Capen wrote:
Quote:
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

*


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Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD
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recapen(at)earthlink.net
Guest
PostPosted: Tue Nov 24, 2009 4:58 am    Post subject: CHT update Reply with quote
Charlie,

I've already done both of these parts as you have suggested. I did them in steps so that I could get the #1 and #3 balanced as well as they are.

Thanks,
Ralph

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recapen(at)earthlink.net
Guest
PostPosted: Tue Nov 24, 2009 5:05 am    Post subject: CHT update Reply with quote
Thanks Robin,

Good to hear this from multiple sources,

Ralph

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