Today's Message Index:
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1. 06:01 AM - Re: engine monitor problem - CHT thermocouples (T. Graziano)
2. 07:27 AM - Re: Re: engine monitor problem (JAPhillipsGA@aol.com)
3. 07:56 AM - Re: Re: engine monitor problem - CHT thermocouples (JAPhillipsGA@aol.com)
4. 04:23 PM - Re: engine monitor problem (Jim Stone)
Message 1
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| Subject: | Re: engine monitor problem - CHT thermocouples |
--> JabiruEngine-List message posted by: "T. Graziano" <tonyplane@bellsouth.net>
Bill,
If your CHT probes are attached to your monitoring instrument, then all you
ahouls have to do is put the "sensening" end of the probe into a know temp
liquid and check your instrument reading. I used to check calibration by
placing the "twisted" end of the thermocouple wire into ice water (32 deg
F/0 deg C) and then into boiling water.
Another thing to do to check the CHT thermocouple position for instrument
reading is to use a hair dryer or other hot air device to put heat onto the
cylinder and check the reading on the instrument. I found that I had two
cylinder location readings reversed when I installed my probes.
Tony Graziano
ZodiacXL/Jab3300A, N493TG, 91 hrs
Time: 09:34:00 AM PST US
From: JAPhillipsGA@aol.com
Subject: Re: JabiruEngine-List: Re: engine monitor problem
--> JabiruEngine-List message posted by: JAPhillipsGA@aol.com
Jim, I think I will try to test my probes as you suggested. Again, how would
you do that ? I have a digital thermometer so would I have to get some water
hot and stick the thermometer probe and the CHT probe in there together and
see
the difference in readings ? You mention grounding. Would I have to run a
ground wire from the CHT probe to the engine ? I remember when I purchased
the
CHT kit the instructions mentioned that they could be off by as much as 75
degrees. Best to you, Bill of Georgia, N505WP, 601X-3300 w/dc and 60 plus
hours
Message 2
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| Subject: | Re: engine monitor problem |
--> JabiruEngine-List message posted by: JAPhillipsGA@aol.com
Jim, thanks for the input. I plan to try testing this weekend at the hanger.
What kind of difference did you find ? and did you check all your CHT probes
or just the hottest ? I don't want to make extra work for myself as every
minute working - is a minute flying, Thanks, Bill of Georgia
do not archive
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| Subject: | Re: engine monitor problem - CHT thermocouples |
--> JabiruEngine-List message posted by: JAPhillipsGA@aol.com
Tony, thanks for the input. I to had two cylinders probes reversed. My real
concern is how much attention I need to pay to the gages. I noticed the other
day that my oil temp went up as the CHTs for 4 & 6 stayed up and moved down as
they went down. I wonder how accurate my oil temp gage is ? Is there a way to
mechanically test this ? When I first started flying her I used a mechanical
gage to test the oil pressure gage and found it reading 10-15 pounds high. Have
you tested yours ? I will be glad to send you the oil gage I used and
fittings if you want. Thanks again, Bill of Georgia
do not archive
Message 4
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| Subject: | Re: engine monitor problem |
--> JabiruEngine-List message posted by: "Jim Stone" <jsto1@tampabay.rr.com>
My tests were more complex then you would typically encounter. This was because
I was testing a custom design before general public release. The firt set of
softeware coefficients gave results that were nowhere near the real worlk, Ref
temp = 385 'F vs displayed value = 223' F. variation between sensors varied
by up to 20% of reference standard.
We eventually scrapped the initial hardware and went to differential sensors for
each line. The process took several months between hardware and software revisions.
All sensors are now +/- 3% of my calibrated reference.
The Great Lakes sytsem has enough volume that I would expect all sensors to show
in the range of +/- 5% compared to a reference standard.
--------
Jim Stone
Jabiru J450 N450SJ
Clearwater FL USA
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