Today's Message Index:
----------------------
1. 08:37 AM - CHT probes (AirEupora)
2. 10:09 AM - Re: CHT probes (kayberg@aol.com)
3. 01:32 PM - Re: CHT probes (FLYaDIVE)
4. 02:18 PM - Re: CHT probes (j. davis)
Message 1
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I have been chasing my tail over the last couple of months looking for a cooling
problem that might not have been an overheating engine.
I have an MGL Voyager on a Jabiru 3300L. The problem now seems to be the differences
between the NEW voltmeter with "K" type probe and the reading that I get
off of the MGL EMS unit from the EFIS display.
I'm reading higher on the MGL. Matt has been working with me and is a great guy,
but I think both of us are having a problem figuring this out.
I have changed the EMS unit out three times. The CHT probes are the gasket types
and I'm thinking now that this is where my problem lie.
The Voltmeter K type is being placed next to the CHT gasket and the readings are
taking off the voltmeter then the MGL EFIS.
Ground run up the other day were as follows:
Cyl Voltmeter MGL difference
1 83 105 20
2 116 151 35
3 110 132 22
4 127 162 35
5 100 145 43
6 113 151 38
On the previous EMS unit
Ground run
1 79 96 17
2 72 94 22
3 85 96 11
4 79 105 26
5 76 94 18
6 76 99 23
After flight and de-cowling mVolts
1 113 149 36 3.5
2 126 164 38 3.9
3 121 157 36 4.1
4 123 159 36 4.2
5 111 145 34 4.1
6 120 156 36 4.3
Does many people have any ideals?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=387158#387158
Message 2
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Here is what seems obvious to me.
1) the wires to and including the MGL have some resistance, which varies by
heat.
2) The variations WHEN UP TO TEMP are predictable, around 37 degrees, so th
ere is no need to change anything, just your mental calibration
3) The probes are remarkably consistant
3) You dont have a problem with overheating
Doug K.
-----Original Message-----
From: AirEupora <AirEupora@sbcglobal.net>
Sent: Wed, Nov 7, 2012 11:38 am
Subject: JabiruEngine-List: CHT probes
et>
I have been chasing my tail over the last couple of months looking for a co
oling
problem that might not have been an overheating engine.
I have an MGL Voyager on a Jabiru 3300L. The problem now seems to be the
differences between the NEW voltmeter with "K" type probe and the reading t
hat I
get off of the MGL EMS unit from the EFIS display.
I'm reading higher on the MGL. Matt has been working with me and is a grea
t
guy, but I think both of us are having a problem figuring this out.
I have changed the EMS unit out three times. The CHT probes are the gasket
types and I'm thinking now that this is where my problem lie.
The Voltmeter K type is being placed next to the CHT gasket and the reading
s are
taking off the voltmeter then the MGL EFIS.
Ground run up the other day were as follows:
Cyl Voltmeter MGL difference
1 83 105 20
2 116 151 35
3 110 132 22
4 127 162 35
5 100 145 43
6 113 151 38
On the previous EMS unit
Ground run
1 79 96 17
2 72 94 22
3 85 96 11
4 79 105 26
5 76 94 18
6 76 99 23
After flight and de-cowling mVolts
1 113 149 36 3.5
2 126 164 38 3.9
3 121 157 36 4.1
4 123 159 36 4.2
5 111 145 34 4.1
6 120 156 36 4.3
Does many people have any ideals?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=387158#387158
Message 3
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Heat Seeker 1:
When you say GASKET type probes. Are you referring to the RING mount
thermocouples that go under the spark plug?
And what are you referring to when you say "NEW voltmeter with'K' type
probe"?
Your statements bring up ALL SORTS OF ISSUES because:
1 - The RING type thermocouples ALWAYS READ HIGHER than cylinder hear
(DRILLED & MOUNTED) PROBES. They are picking up the heat dissipation of
the spark plug AND they are lowering the heat transfer between the spark
plug and the cylinder head. Neither case is good. Get rid of RING type
thermocouples.
Because of ring type spark plugs will change the operational temp range.
They will go UP. Because heat transfer is poor with the ring coupler.
2 - You use the statement "NEW voltmeter with'K' type probe" - K type
probes ARE NOT VOLTAGE items. They are CURRENT probes. They produce a
very small current and if you are using a volt meter to read them your
numbers will not be correct.
3 - CHT & EGT are REFERENCE temperatures. Unless you have a lab type unit
where differences in probes can be zeroed out there will be differences in
readings. Differences that relate to: a> Length of probe wire. b> How the
probe was made; twisted, soldered, or welded. c> Calibration of the readout
head. d> Even the number of twists can change the readings.
4 - There are also differences in probes as far as GROUNDED and
UN-GROUNDED. You can NOT mix the two. Do yo know exactly what each prop
is?
Just to let you know you are not the only one with difference problems with
temperatures - E.I. and JPI always show differences in values.
Barry
On Wed, Nov 7, 2012 at 11:36 AM, AirEupora <AirEupora@sbcglobal.net> wrote:
> AirEupora@sbcglobal.net>
>
> I have been chasing my tail over the last couple of months looking for a
> cooling problem that might not have been an overheating engine.
>
> I have an MGL Voyager on a Jabiru 3300L. The problem now seems to be the
> differences between the NEW voltmeter with "K" type probe and the reading
> that I get off of the MGL EMS unit from the EFIS display.
>
> I'm reading higher on the MGL. Matt has been working with me and is a
> great guy, but I think both of us are having a problem figuring this out.
>
> I have changed the EMS unit out three times. The CHT probes are the
> gasket types and I'm thinking now that this is where my problem lie.
>
> The Voltmeter K type is being placed next to the CHT gasket and the
> readings are taking off the voltmeter then the MGL EFIS.
>
> Ground run up the other day were as follows:
> Cyl Voltmeter MGL difference
> 1 83 105 20
> 2 116 151 35
> 3 110 132 22
> 4 127 162 35
> 5 100 145 43
> 6 113 151 38
>
> On the previous EMS unit
> Ground run
> 1 79 96 17
> 2 72 94 22
> 3 85 96 11
> 4 79 105 26
> 5 76 94 18
> 6 76 99 23
>
> After flight and de-cowling mVolts
> 1 113 149 36 3.5
> 2 126 164 38 3.9
> 3 121 157 36 4.1
> 4 123 159 36 4.2
> 5 111 145 34 4.1
> 6 120 156 36 4.3
>
> Does many people have any ideals?
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=387158#387158
>
>
Message 4
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On 11/07/2012 04:31 PM, FLYaDIVE wrote:
> Heat Seeker 1:
>
> When you say GASKET type probes. Are you referring to the RING mount thermocouples
that
> go under the spark plug?
> And what are you referring to when you say "NEW voltmeter with'K' type probe"?
>
> Your statements bring up ALL SORTS OF ISSUES because:
> 1 - The RING type thermocouples ALWAYS READ HIGHER than cylinder hear (DRILLED
& MOUNTED)
> PROBES. They are picking up the heat dissipation of the spark plug AND they
are lowering
> the heat transfer between the spark plug and the cylinder head. Neither case
is good.
> Get rid of RING type thermocouples.
> Because of ring type spark plugs will change the operational temp range. They
will go UP.
> Because heat transfer is poor with the ring coupler.
> 2 - You use the statement "NEW voltmeter with'K' type probe" - K type probes
ARE NOT
> VOLTAGE items. They are CURRENT probes. They produce a very small current and
if you are
> using a volt meter to read them your numbers will not be correct.
> 3 - CHT & EGT are REFERENCE temperatures. Unless you have a lab type unit
> where differences in probes can be zeroed out there will be differences in readings.
> Differences that relate to: a> Length of probe wire. b> How the probe was made;
twisted,
> soldered, or welded. c> Calibration of the readout head. d> Even the number of
twists can
> change the readings.
> 4 - There are also differences in probes as far as GROUNDED and UN-GROUNDED.
You can NOT
> mix the two. Do yo know exactly what each prop is?
>
> Just to let you know you are not the only one with difference problems with temperatures
-
> E.I. and JPI always show differences in values.
>
> Barry
Excellent post, Barry, many valid points.
>
>
> On Wed, Nov 7, 2012 at 11:36 AM, AirEupora <AirEupora@sbcglobal.net
> <mailto:AirEupora@sbcglobal.net>> wrote:
>
> <mailto:AirEupora@sbcglobal.net>>
>
> I have been chasing my tail over the last couple of months looking for a
cooling
> problem that might not have been an overheating engine.
>
> I have an MGL Voyager on a Jabiru 3300L. The problem now seems to be the
differences
> between the NEW voltmeter with "K" type probe and the reading that I get
off of the
> MGL EMS unit from the EFIS display.
>
> I'm reading higher on the MGL. Matt has been working with me and is a great
guy, but
> I think both of us are having a problem figuring this out.
>
> I have changed the EMS unit out three times. The CHT probes are the gasket
types and
> I'm thinking now that this is where my problem lie.
>
> The Voltmeter K type is being placed next to the CHT gasket and the readings
are
> taking off the voltmeter then the MGL EFIS.
>
> Ground run up the other day were as follows:
> Cyl Voltmeter MGL difference
> 1 83 105 20
> 2 116 151 35
> 3 110 132 22
> 4 127 162 35
> 5 100 145 43
> 6 113 151 38
>
> On the previous EMS unit
> Ground run
> 1 79 96 17
> 2 72 94 22
> 3 85 96 11
> 4 79 105 26
> 5 76 94 18
> 6 76 99 23
>
> After flight and de-cowling mVolts
> 1 113 149 36 3.5
> 2 126 164 38 3.9
> 3 121 157 36 4.1
> 4 123 159 36 4.2
> 5 111 145 34 4.1
> 6 120 156 36 4.3
>
> Does many people have any ideals?
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=387158#387158
>
>
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>
--
Regards, J.
- Sonex #325 C-FJNJ, Jab 3300a, Prince P-Tip, Aerocarb
- former C-IGGY CH701 owner/builder, CH750 in progress
-----------------------------
J. Davis, M.Sc. (comp sci)
email: jwd3ca at gmail dot com
*NIX consulting, SysAdmin
http://cleco.ca
and now... Deep Thought #61, by Jack Handy
Whenever I see an old lady slip and fall on a wet sidewalk, my first instinct
is to laugh. But then I think, what if I was an ant, and she fell on me. Then it
wouldn't seem quite so funny.
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