Today's Message Index:
----------------------
1. 04:49 AM - Re: EGT Probes (Andy Silvester)
2. 08:35 AM - Re: EGT Probes (Lynn Matteson)
3. 03:24 PM - Re: EGT Probes (Andy Silvester)
4. 03:40 PM - Re: EGT Probes (Keith Pickford)
5. 05:44 PM - Re: EGT Probes (Chuck Deiterich)
Message 1
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Lynn,
I think you probably have the 'edge' over me on thermocouple technology, but
with these EGT senders, you're attempting to measure a pipe full of very
fast moving hot gas and I doubt, with the turbulence of post-combustion,
anyone can really tell where (in the pipe diameter) the best place for true
measurement is. Unless of course you could spend considerable time in
laboratory conditions measuring.....We've always used the 1" probes,
supplied mainly from Grand Rapids Technologies and as a measure of EGT, they
do a fair job. After all, EGT is very much a 'comparative' measurement and
it's always the case to see a wider range of temps across all cylinders,
(even when in the case of a direct-injected engine where mixture is more
accurately known), than you'd see for example in a well-balanced set of CHT
figures. What you'll be looking for is a temperature span of less than (say)
80F-100F across cylinders (less is good but often not worth chasing), but
the absolute values will tell you more about how the engine's doing:
1. Less than 1100F will betray an over-rich condition
2. Above 1400F is too lean, particularly at full throttle.
Remember, the Bing's mixture compensating needle will promote a relatively
rich mixture at high throttle openings (so the high workload won't lead to
detonation) and a relatively lean condition in the cruise. Prop selection,
airframe type, fuel quality all have effects, but essentially I get my
confidence from a good-running engine by seeing (say) cruise EGTs around
1250F-1300F, and wide-open throttle EGTs about 100F less. Opening the
throttle to full while monitoring the EGTs will see a marked reduction.
Comprehensive info on this subject can be found in Jabiru's Service Bulletin
JSB 018-1 at:
http://www.jabiru.net.au/Service%20Bulletins/Engine%20files/JSB018-1Engine%2
0tuning.pdf
There's plenty of accepted wisdom about the benefits of multiple EGT
measurement; noting a rising EGT on a cylinder could help to diagnose an
air-leak in the induction and signal the need for maintenance before an
expensive head overhaul becomes necessary. Thanks, Lynn for providing the
opportunity to neatly evade your topic and (no doubt) raise discussion about
another..!
Cheers, Andy
Suncoast Sportplanes, Inc.
-----Original Message-----
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Lynn
Matteson
Sent: 09 February 2008 18:08
Subject: Re: JabiruEngine-List: EGT Probes
Andy-
Wouldn't you want the tip of the probe to be in the center of the
pipe? It's been my experience (a few years spent installing
thermocouples in test cars for Chrysler Corp) that it's where the two
dissimilar wires come together...usually at the tip of the
thermocouple...that the reading is made. I'll certainly defer to your
knowledge of the thermocouples in question....I know nothing about
those particular ones.
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/470+ hrs
On Feb 9, 2008, at 10:39 AM, Andy Silvester wrote:
> Chuck,
>
>
> Get the 1" ones; they'll span the inside diameter of the exhaust
> pipes nicely.
>
>
> Andy Silvester
>
> Suncoast Sportplanes, Inc
>
> 813 377 2716
>
>
> From: owner-jabiruengine-list-server@matronics.com [mailto:owner-
> jabiruengine-list-server@matronics.com] On Behalf Of Chuck Deiterich
> Sent: 09 February 2008 12:59
> To: Jab-list
> Subject: JabiruEngine-List: EGT Probes
>
>
> I am going to add EGT's to my 2200 (SN 988).
> I can get probes that are either 1/2 inch long or 1 inch long.
> Any comments on which length should I get?
>
> Chuck D.
>
> forums.matronics.com_-
> ============================================================ _-
> contribution_-
> ===========================================================
Message 2
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Thanks for the info, Andy. I've got all four cyls monitored with
Grand Rapids Technologies probes, and their EIS. I'm not sure what
length they are, but I recall having to stack about 1/8" of washers
onto the probe so as to prevent it from entering the pipe too far. I
can't really recall where this put the probe in relationship to the
center of the pipe...maybe it just kept it from touching the other
side of the pipe, which wouldn't be good for readings.
My particular readings are in the 1300's F at full throttle, all
within 40F, and in the 1400's F at cruise. I've got engine #2062
which had the economy tune at the time of delivery, and I haven't
changed it. Sounds like maybe I'd better go a little richer, eh?
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/470+ hrs
On Feb 10, 2008, at 7:44 AM, Andy Silvester wrote:
> <andy@suncoastjabiru.com>
>
> Lynn,
>
> I think you probably have the 'edge' over me on thermocouple
> technology, but
> with these EGT senders, you're attempting to measure a pipe full of
> very
> fast moving hot gas and I doubt, with the turbulence of post-
> combustion,
> anyone can really tell where (in the pipe diameter) the best place
> for true
> measurement is. Unless of course you could spend considerable time in
> laboratory conditions measuring.....We've always used the 1" probes,
> supplied mainly from Grand Rapids Technologies and as a measure of
> EGT, they
> do a fair job. After all, EGT is very much a 'comparative'
> measurement and
> it's always the case to see a wider range of temps across all
> cylinders,
> (even when in the case of a direct-injected engine where mixture is
> more
> accurately known), than you'd see for example in a well-balanced
> set of CHT
> figures. What you'll be looking for is a temperature span of less
> than (say)
> 80F-100F across cylinders (less is good but often not worth
> chasing), but
> the absolute values will tell you more about how the engine's doing:
>
> 1. Less than 1100F will betray an over-rich condition
> 2. Above 1400F is too lean, particularly at full throttle.
>
> Remember, the Bing's mixture compensating needle will promote a
> relatively
> rich mixture at high throttle openings (so the high workload won't
> lead to
> detonation) and a relatively lean condition in the cruise. Prop
> selection,
> airframe type, fuel quality all have effects, but essentially I get my
> confidence from a good-running engine by seeing (say) cruise EGTs
> around
> 1250F-1300F, and wide-open throttle EGTs about 100F less. Opening the
> throttle to full while monitoring the EGTs will see a marked
> reduction.
> Comprehensive info on this subject can be found in Jabiru's Service
> Bulletin
> JSB 018-1 at:
> http://www.jabiru.net.au/Service%20Bulletins/Engine%20files/
> JSB018-1Engine%2
> 0tuning.pdf
>
> There's plenty of accepted wisdom about the benefits of multiple EGT
> measurement; noting a rising EGT on a cylinder could help to
> diagnose an
> air-leak in the induction and signal the need for maintenance
> before an
> expensive head overhaul becomes necessary. Thanks, Lynn for
> providing the
> opportunity to neatly evade your topic and (no doubt) raise
> discussion about
> another..!
>
> Cheers, Andy
> Suncoast Sportplanes, Inc.
>
Message 3
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Lynn,
Actually, those temps and 'span' are very good; I wouldn't change a thing,
particularly on the 2200. I have run our own engines hotter (in the 1400s at
cruise) and with no ill-effects in a few hundred hours, but it's a little
higher than Jabiru's own recommendations. As long as you're seeing that drop
on increase in throttle, you're good with what you have, and no doubt a
pretty good g.p.h. figure.
Andy
-----Original Message-----
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Lynn
Matteson
Sent: 10 February 2008 14:31
Subject: Re: JabiruEngine-List: EGT Probes
Thanks for the info, Andy. I've got all four cyls monitored with
Grand Rapids Technologies probes, and their EIS. I'm not sure what
length they are, but I recall having to stack about 1/8" of washers
onto the probe so as to prevent it from entering the pipe too far. I
can't really recall where this put the probe in relationship to the
center of the pipe...maybe it just kept it from touching the other
side of the pipe, which wouldn't be good for readings.
My particular readings are in the 1300's F at full throttle, all
within 40F, and in the 1400's F at cruise. I've got engine #2062
which had the economy tune at the time of delivery, and I haven't
changed it. Sounds like maybe I'd better go a little richer, eh?
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/470+ hrs
On Feb 10, 2008, at 7:44 AM, Andy Silvester wrote:
> <andy@suncoastjabiru.com>
>
> Lynn,
>
> I think you probably have the 'edge' over me on thermocouple
> technology, but
> with these EGT senders, you're attempting to measure a pipe full of
> very
> fast moving hot gas and I doubt, with the turbulence of post-
> combustion,
> anyone can really tell where (in the pipe diameter) the best place
> for true
> measurement is. Unless of course you could spend considerable time in
> laboratory conditions measuring.....We've always used the 1" probes,
> supplied mainly from Grand Rapids Technologies and as a measure of
> EGT, they
> do a fair job. After all, EGT is very much a 'comparative'
> measurement and
> it's always the case to see a wider range of temps across all
> cylinders,
> (even when in the case of a direct-injected engine where mixture is
> more
> accurately known), than you'd see for example in a well-balanced
> set of CHT
> figures. What you'll be looking for is a temperature span of less
> than (say)
> 80F-100F across cylinders (less is good but often not worth
> chasing), but
> the absolute values will tell you more about how the engine's doing:
>
> 1. Less than 1100F will betray an over-rich condition
> 2. Above 1400F is too lean, particularly at full throttle.
>
> Remember, the Bing's mixture compensating needle will promote a
> relatively
> rich mixture at high throttle openings (so the high workload won't
> lead to
> detonation) and a relatively lean condition in the cruise. Prop
> selection,
> airframe type, fuel quality all have effects, but essentially I get my
> confidence from a good-running engine by seeing (say) cruise EGTs
> around
> 1250F-1300F, and wide-open throttle EGTs about 100F less. Opening the
> throttle to full while monitoring the EGTs will see a marked
> reduction.
> Comprehensive info on this subject can be found in Jabiru's Service
> Bulletin
> JSB 018-1 at:
> http://www.jabiru.net.au/Service%20Bulletins/Engine%20files/
> JSB018-1Engine%2
> 0tuning.pdf
>
> There's plenty of accepted wisdom about the benefits of multiple EGT
> measurement; noting a rising EGT on a cylinder could help to
> diagnose an
> air-leak in the induction and signal the need for maintenance
> before an
> expensive head overhaul becomes necessary. Thanks, Lynn for
> providing the
> opportunity to neatly evade your topic and (no doubt) raise
> discussion about
> another..!
>
> Cheers, Andy
> Suncoast Sportplanes, Inc.
>
Message 4
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Wasn't there a recommendation to drill the main jet out slightly on the
tuning kit ?
Keith
-----Original Message-----
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Andy
Silvester
Sent: Monday, February 11, 2008 12:18 PM
Subject: RE: JabiruEngine-List: EGT Probes
<andy@suncoastjabiru.com>
Lynn,
Actually, those temps and 'span' are very good; I wouldn't change a
thing,
particularly on the 2200. I have run our own engines hotter (in the
1400s at
cruise) and with no ill-effects in a few hundred hours, but it's a
little
higher than Jabiru's own recommendations. As long as you're seeing that
drop
on increase in throttle, you're good with what you have, and no doubt a
pretty good g.p.h. figure.
Andy
-----Original Message-----
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Lynn
Matteson
Sent: 10 February 2008 14:31
Subject: Re: JabiruEngine-List: EGT Probes
<lynnmatt@jps.net>
Thanks for the info, Andy. I've got all four cyls monitored with
Grand Rapids Technologies probes, and their EIS. I'm not sure what
length they are, but I recall having to stack about 1/8" of washers
onto the probe so as to prevent it from entering the pipe too far. I
can't really recall where this put the probe in relationship to the
center of the pipe...maybe it just kept it from touching the other
side of the pipe, which wouldn't be good for readings.
My particular readings are in the 1300's F at full throttle, all
within 40F, and in the 1400's F at cruise. I've got engine #2062
which had the economy tune at the time of delivery, and I haven't
changed it. Sounds like maybe I'd better go a little richer, eh?
Lynn Matteson
Grass Lake, Michigan
Kitfox IV Speedster w/Jabiru 2200
flying w/470+ hrs
On Feb 10, 2008, at 7:44 AM, Andy Silvester wrote:
> <andy@suncoastjabiru.com>
>
> Lynn,
>
> I think you probably have the 'edge' over me on thermocouple
> technology, but
> with these EGT senders, you're attempting to measure a pipe full of
> very
> fast moving hot gas and I doubt, with the turbulence of post-
> combustion,
> anyone can really tell where (in the pipe diameter) the best place
> for true
> measurement is. Unless of course you could spend considerable time in
> laboratory conditions measuring.....We've always used the 1" probes,
> supplied mainly from Grand Rapids Technologies and as a measure of
> EGT, they
> do a fair job. After all, EGT is very much a 'comparative'
> measurement and
> it's always the case to see a wider range of temps across all
> cylinders,
> (even when in the case of a direct-injected engine where mixture is
> more
> accurately known), than you'd see for example in a well-balanced
> set of CHT
> figures. What you'll be looking for is a temperature span of less
> than (say)
> 80F-100F across cylinders (less is good but often not worth
> chasing), but
> the absolute values will tell you more about how the engine's doing:
>
> 1. Less than 1100F will betray an over-rich condition
> 2. Above 1400F is too lean, particularly at full throttle.
>
> Remember, the Bing's mixture compensating needle will promote a
> relatively
> rich mixture at high throttle openings (so the high workload won't
> lead to
> detonation) and a relatively lean condition in the cruise. Prop
> selection,
> airframe type, fuel quality all have effects, but essentially I get my
> confidence from a good-running engine by seeing (say) cruise EGTs
> around
> 1250F-1300F, and wide-open throttle EGTs about 100F less. Opening the
> throttle to full while monitoring the EGTs will see a marked
> reduction.
> Comprehensive info on this subject can be found in Jabiru's Service
> Bulletin
> JSB 018-1 at:
> http://www.jabiru.net.au/Service%20Bulletins/Engine%20files/
> JSB018-1Engine%2
> 0tuning.pdf
>
> There's plenty of accepted wisdom about the benefits of multiple EGT
> measurement; noting a rising EGT on a cylinder could help to
> diagnose an
> air-leak in the induction and signal the need for maintenance
> before an
> expensive head overhaul becomes necessary. Thanks, Lynn for
> providing the
> opportunity to neatly evade your topic and (no doubt) raise
> discussion about
> another..!
>
> Cheers, Andy
> Suncoast Sportplanes, Inc.
>
Message 5
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Andy and Lynn,
Thanks for the response.
I searched around the internet and also looked at Tony Bingelis' books.
His book just has a drawing that shows the tip of the probe in the center.
One place said the tip should be in the center of the gas stream
I suspect in the center is the hottest.
So that is what I will try to do.
Chuck D.
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