Today's Message Index:
----------------------
1. 07:19 AM - EGT Spread Question-Rejetted (MHerder)
2. 08:41 AM - Re: EGT Spread Question-Rejetted (BobsV35B@aol.com)
3. 12:01 PM - Re: EGT Spread Question-Rejetted (Pete Krotje)
4. 02:52 PM - Re: EGT Spread Question-Rejetted (BobsV35B@aol.com)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | EGT Spread Question-Rejetted |
I just rejetted to a .250 main , and thing are running a lot smoother, no more
soot, CHTs are perfect, oilt temp perfect, and most of the EGTs are with one
being a little higher than the rest Highest is 1325, lowest is 1190 or so with
the other four in the middle. Ive only run it rejetted for about an hour, so
I wanted to check in with everyone and make sure Im not hurting anything.
Ive got about 7 hrs on the engine and granted it is cooler than normal here in
Texas, but Ive not had any CHT issues, or Oil Temperature issues. I followed
the recommendations by Jabiru to the T regarding baffle design, ridges, the front
gate etc. Maybe Im just lucky? I was really anticipating having to fiddle
with this, not that Im disappointed.
A few questions:
At MWOT at level flight what is your EGT spread?
Which cylinder give you the hottest and coldest egts.
I understand that any disparity is most likely due to one cylinder getting more
fuel than the others or less fuel for higher egt. I just want to find out what
is realistically achievable with a carbureted engine.
Also, and most perplexing to me Ive been doing some reading on possible causes
of high egt. One of the items that came up as a possibility was that one plug
could be fouled. This is the exact opposite of what I thought would be the
case. I thought if you would have a fouled plug, that the combustion might not
be as complete and that the egt would be lower. Can someone please explain.
--------
One Rivet at a Time!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328197#328197
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: EGT Spread Question-Rejetted |
Good Morning Mike,
When only one plug is firing, it takes longer for the burn to be completed
.
That means that the peak temperature occurs later in the cycle and closer
to the time the exhaust valve opens giving you a higher reading on the EG
T.
Brings home the point that we really should NOT worry about what the
temperature actually is, we should evaluate EGT readings based on how they
relate to some predetermined point.
You may recall that when Al Hundere, the fellow who popularized the use of
an EGT gauge for us, made his first gauges available, they had no specific
temperature on the gauge. We just had indices that were twenty-five degree
s
Fahrenheit apart. We were to find the peak temperature by careful leaning
,
then adjust the instrument so that the reading was at a little star place
on the instrument. All further leaning or enrichment was based on the
difference, either richer or leaner, than that peak EGT point.
Help at all?
Incidentally the name AlCor comes from Al's Corporation.
Happy Skies,
Old Bob
In a message dated 1/24/2011 9:19:22 A.M. Central Standard Time,
michaelherder@beckgroup.com writes:
--> JabiruEngine-List message posted by: "MHerder"
<michaelherder@beckgroup.com>
I just rejetted to a .250 main , and thing are running a lot smoother,
no
more soot, CHT=C3=A2=82=AC=84=A2s are perfect, oilt temp perfect,
and most of the EGT=C3=A2=82=AC=84=A2
s are with one being a little higher than the rest=C3=A2=82=AC=C2
Highest is 1325,
lowest is 1190 or so with the other four in the middle. I=C3=A2=82=AC
=84=A2ve only run it
rejetted for about an hour, so I wanted to check in with everyone and mak
e
sure I=C3=A2=82=AC=84=A2m not hurting anything.
I=C3=A2=82=AC=84=A2ve got about 7 hrs on the engine and granted it
is cooler than normal
here in Texas, but I=C3=A2=82=AC=84=A2ve not had any CHT issues, or
Oil Temperature
issues. I followed the recommendations by Jabiru to the T regarding baff
le
design, ridges, the front gate etc. Maybe I=C3=A2=82=AC=84=A2m just
lucky? I was really
anticipating having to fiddle with this, not that I=C3=A2=82=AC=84
=A2m disappointed.
A few questions:
At MWOT at level flight what is your EGT spread?
Which cylinder give you the hottest and coldest egt=C3=A2=82=AC=84
=A2s.
I understand that any disparity is most likely due to one cylinder gettin
g
more fuel than the others or less fuel for higher egt. I just want to
find out what is realistically achievable with a carbureted engine.
Also, and most perplexing to me=C3=A2=82=AC=C2 I=C3=A2=82=AC
=84=A2ve been doing some reading on
possible causes of high egt. One of the items that came up as a possibil
ity
was that one plug could be fouled. This is the exact opposite of what I
thought would be the case. I thought if you would have a fouled plug, th
at
the combustion might not be as complete and that the egt would be lower.
Can
someone please explain.
--------
One Rivet at a Time!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328197#328197
========================
===========
========================
===========
========================
===========
========================
===========
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | EGT Spread Question-Rejetted |
Old Bob=99s analysis may apply to Lyc and Continental engines
where the plugs are far apart and the flame in initiated from the top
and bottom of the cylinder. Jabiru cylinders are smaller and the plugs
are close together and the effect is hardly noticeable. I=99ve
flown on one mag and then switched to both and observed no difference in
temps whatsoever and no difference in rpm. I=99ve flown with one
plug not firing (plug wire came off) and saw no differences in EGT and
really only discovered that there was a problem when I did a mag check
before shut down.
Pete
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of
BobsV35B@aol.com
Sent: Monday, January 24, 2011 10:32 AM
Subject: Re: JabiruEngine-List: EGT Spread Question-Rejetted
Good Morning Mike,
When only one plug is firing, it takes longer for the burn to be
completed. That means that the peak temperature occurs later in the
cycle and closer to the time the exhaust valve opens giving you a higher
reading on the EGT.
Brings home the point that we really should NOT worry about what the
temperature actually is, we should evaluate EGT readings based on how
they relate to some predetermined point.
You may recall that when Al Hundere, the fellow who popularized the use
of an EGT gauge for us, made his first gauges available, they had no
specific temperature on the gauge. We just had indices that were
twenty-five degrees Fahrenheit apart. We were to find the peak
temperature by careful leaning, then adjust the instrument so that the
reading was at a little star place on the instrument. All further
leaning or enrichment was based on the difference, either richer or
leaner, than that peak EGT point.
Help at all?
Incidentally the name AlCor comes from Al's Corporation.
Happy Skies,
Old Bob
In a message dated 1/24/2011 9:19:22 A.M. Central Standard Time,
michaelherder@beckgroup.com writes:
<michaelherder@beckgroup.com>
I just rejetted to a .250 main , and thing are running a lot smoother,
no more soot, CHT=C3=A2=82=AC=84=A2s are perfect, oilt temp
perfect, and most of the EGT=C3=A2=82=AC=84=A2s are with one being
a little higher than the rest=C3=A2=82=AC=C2 Highest is 1325,
lowest is 1190 or so with the other four in the middle.
I=C3=A2=82=AC=84=A2ve only run it rejetted for about an hour, so I
wanted to check in with everyone and make sure
I=C3=A2=82=AC=84=A2m not hurting anything.
I=C3=A2=82=AC=84=A2ve got about 7 hrs on the engine and granted it
is cooler than normal here in Texas, but I=C3=A2=82=AC=84=A2ve not
had any CHT issues, or Oil Temperature issues. I followed the
recommendations by Jabiru to the T regarding baffle design, ridges, the
front gate etc. Maybe I=C3=A2=82=AC=84=A2m just lucky? I was
really anticipating having to fiddle with this, not that
I=C3=A2=82=AC=84=A2m disappointed.
A few questions:
At MWOT at level flight what is your EGT spread?
Which cylinder give you the hottest and coldest
egt=C3=A2=82=AC=84=A2s.
I understand that any disparity is most likely due to one cylinder
getting more fuel than the others or less fuel for higher egt. I just
want to find out what is realistically achievable with a carbureted
engine.
Also, and most perplexing to me=C3=A2=82=AC=C2
I=C3=A2=82=AC=84=A2ve been doing some reading on possible causes
of high egt. One of the items that came up as a possibility was that
one plug could be fouled. This is the exact opposite of what I thought
would be the case. I thought if you would have a fouled plug, that the
combustion might not be as complete and that the egt would be lower.
Can someone please explain.
--------
One Rivet at a Time!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328197#328197=====
================
=======================
- MATRONICS WEB FORUMS
=======================
- List Contribution Web Site sp;
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: EGT Spread Question-Rejetted |
Good Afternoon Pete,
That sounds reasonable to me.
As Always, It All Depends! <G>
Happy Skies,
Old Bob
In a message dated 1/24/2011 2:01:34 P.M. Central Standard Time,
pete@usjabiru.com writes:
Old Bob=99s analysis may apply to Lyc and Continental engines where
the
plugs are far apart and the flame in initiated from the top and bottom of
the
cylinder. Jabiru cylinders are smaller and the plugs are close together
and the effect is hardly noticeable. I=99ve flown on one mag and th
en switched
to both and observed no difference in temps whatsoever and no difference
in rpm. I=99ve flown with one plug not firing (plug wire came off)
and saw no
differences in EGT and really only discovered that there was a problem
when I did a mag check before shut down.
Pete
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of BobsV3
5B@aol.com
Sent: Monday, January 24, 2011 10:32 AM
Subject: Re: JabiruEngine-List: EGT Spread Question-Rejetted
Good Morning Mike,
When only one plug is firing, it takes longer for the burn to be
completed. That means that the peak temperature occurs later in the cycle
and closer
to the time the exhaust valve opens giving you a higher reading on the
EGT.
Brings home the point that we really should NOT worry about what the
temperature actually is, we should evaluate EGT readings based on how the
y
relate to some predetermined point.
You may recall that when Al Hundere, the fellow who popularized the use
of
an EGT gauge for us, made his first gauges available, they had no specifi
c
temperature on the gauge. We just had indices that were twenty-five
degrees Fahrenheit apart. We were to find the peak temperature by careful
leaning, then adjust the instrument so that the reading was at a little
star place
on the instrument. All further leaning or enrichment was based on the
difference, either richer or leaner, than that peak EGT point.
Help at all?
Incidentally the name AlCor comes from Al's Corporation.
Happy Skies,
Old Bob
In a message dated 1/24/2011 9:19:22 A.M. Central Standard Time,
michaelherder@beckgroup.com writes:
--> JabiruEngine-List message posted by: "MHerder"
<michaelherder@beckgroup.com>
I just rejetted to a .250 main , and thing are running a lot smoother,
no
more soot, CHT=C3=A2=82=AC=84=A2s are perfect, oilt temp perfect,
and most of the EGT=C3=A2=82=AC=84=A2
s are with one being a little higher than the rest=C3=A2=82=AC=C2
Highest is 1325,
lowest is 1190 or so with the other four in the middle. I=C3=A2=82=AC
=84=A2ve only run it
rejetted for about an hour, so I wanted to check in with everyone and mak
e
sure I=C3=A2=82=AC=84=A2m not hurting anything.
I=C3=A2=82=AC=84=A2ve got about 7 hrs on the engine and granted it
is cooler than normal
here in Texas, but I=C3=A2=82=AC=84=A2ve not had any CHT issues, or
Oil Temperature
issues. I followed the recommendations by Jabiru to the T regarding baff
le
design, ridges, the front gate etc. Maybe I=C3=A2=82=AC=84=A2m jus
t lucky? I was really
anticipating having to fiddle with this, not that I=C3=A2=82=AC=84
=A2m disappointed.
A few questions:
At MWOT at level flight what is your EGT spread?
Which cylinder give you the hottest and coldest egt=C3=A2=82=AC=84
=A2s.
I understand that any disparity is most likely due to one cylinder gettin
g
more fuel than the others or less fuel for higher egt. I just want to
find out what is realistically achievable with a carbureted engine.
Also, and most perplexing to me=C3=A2=82=AC=C2 I=C3=A2=82=AC
=84=A2ve been doing some reading on
possible causes of high egt. One of the items that came up as a possibil
ity
was that one plug could be fouled. This is the exact opposite of what I
thought would be the case. I thought if you would have a fouled plug, th
at
the combustion might not be as complete and that the egt would be lower.
Can someone please explain.
--------
One Rivet at a Time!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328197#328197=nbsp; =
Use
utilities Day ====================
=== - MATRONICS WEB FORUMS
=======================
- List Contribution Web Site sp;
http://www.matronics.com/Navigator?JabiruEngine-List
http://forums.matronics.com
http://www.matronics.com/contribution
========================
============
(http://www.matronics.com/Navigator?JabiruEngine-List)
========================
============
========================
============
(http://www.matronics.com/contribution)
========================
============
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|