Today's Message Index:
----------------------
1. 07:20 AM - Newest GAMI lean test...probably off-topic for most (Lynn Matteson)
2. 08:34 AM - Re: Newest GAMI lean test...probably off-topic for most (Marvin Williams)
3. 10:53 AM - Re: Newest GAMI lean test...probably off-topic for most (Lynn Matteson)
4. 11:17 AM - Re: Newest GAMI lean test...probably off-topic for most (FLYaDIVE)
5. 02:03 PM - Re: Newest GAMI lean test...probably off-topic for most (kayberg@aol.com)
6. 02:15 PM - Re: Newest GAMI lean test...probably off-topic for most (Marvin)
7. 05:04 PM - Re: Newest GAMI lean test...probably off-topic for most (Marvin Williams)
8. 05:37 PM - Re: Newest GAMI lean test...probably off-topic for most (Lynn Matteson)
9. 06:04 PM - Re: Newest GAMI lean test...probably off-topic for most (Lynn Matteson)
10. 06:26 PM - Re: Newest GAMI lean test...probably off-topic for most (FLYaDIVE)
Message 1
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| Subject: | Newest GAMI lean test...probably off-topic for most |
I hadn't done a Gami Lean Test since I first installed my Rotec TBI
back in 2009, and so yesterday and today I did another few tests.
Back when I first installed the TBI, the Gami spread was 0.1 on one
test, and two other tests showed a 0.3 spread. This was done using
the Jabiru intake manifold and the rubber tube connecter. Thinking
back, the 0.1 might have been a fluke, or bad reading. Since then, I
had built three different intake manifolds out of aluminum tubing and
plate, using different configurations...updraft, backdraft, etc. The
latest manifold is a "ram induction" manifold with runners 19" long.
I've had this one on for about 16 months.... 236 hours flying time.
Because things were going well with this manifold, I had just
forgotten about actually giving the engine the Gami lean test.
Over the last two days, the tests, at 7000 feet yesterday, and 3300
feet today (MSL), all showed a spread of 0.1......from 2.8 gph to 2.7
gph at 2900 rpm and 7000 feet, and 3.4 to 3.3 gph at 2900 rpm at 3300
feet. During these tests, when going from one fuel flow reading to
0.1 less fuel...leaner....all four EGT readings would drop at the
same time. They would be stabilized at one fuel flow setting, and
about a half-turn of the vernier mixture knob, and all four would
start dropping....every time. So this latest manifold is a keeper, as
far as distributing fuel is concerned.
And that is probably the reason that I can dawdle along, burning as
low as 2.5-2.6 gph and the engine still lives...knocking on wood!
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Prince prop 64 x 30, P-tip
Electroair direct-fire ignition system
Rotec TBI-40 injection (sleeved to 36mm)
Status: flying with 1336 hrs... (since 3-27-2006)
Message 2
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| Subject: | Re: Newest GAMI lean test...probably off-topic for |
most
OK Lynn, I'll bite.- Tell us 'dummies' exactly how you performed your GAM
I Lean Tests.- Sounds interesting.- Also, how about some photos of your
latest intake system.=0A=0ANice to hear from you.=0A=0AMarvin=0A=0A=0A=0A
=0A________________________________=0A From: Lynn Matteson <lynnmatt@jps.ne
t>=0ATo: jabiruengines@yahoogroups.com; jabiruengine-list@matronics.com =0A
Sent: Wednesday, August 22, 2012 7:19 AM=0ASubject: JabiruEngine-List: Newe
st GAMI lean test...probably off-topic for most=0A =0A--> JabiruEngine-List
message posted by: Lynn Matteson <lynnmatt@jps.net>=0A=0AI hadn't done a G
ami Lean Test since I first installed my Rotec TBI back in 2009, and so yes
terday and today I did another few tests. Back when I first installed the T
BI, the Gami spread was 0.1 on one test, and two other tests showed a 0.3 s
pread. This was done using the Jabiru intake manifold and the rubber tube c
onnecter. Thinking back, the 0.1 might have been a fluke, or bad reading. S
ince then, I had built three different intake manifolds out of aluminum tub
ing and plate, using different configurations...updraft, backdraft, etc. Th
e latest manifold is a "ram induction" manifold with runners 19" long. I've
had this one on for about 16 months.... 236 hours flying time. Because thi
ngs were going well with this manifold, I had just forgotten about actually
giving the engine the Gami lean test.=0A=0AOver the last two days, the tes
ts, at 7000 feet yesterday, and 3300 feet today (MSL), all showed a spread
of 0.1......from 2.8 gph to 2.7 gph at 2900 rpm and 7000 feet, and 3.4 to 3
.3 gph at 2900 rpm at 3300 feet. During these tests, when going from one fu
el flow reading to 0.1 less fuel...leaner....all four EGT readings would dr
op at the same time. They would be stabilized at one fuel flow setting, and
about a half-turn of the vernier mixture knob, and all four would start dr
opping....every time. So this latest manifold is a keeper, as far as distri
buting fuel is concerned.=0AAnd that is probably the reason that I can dawd
le along, burning as low as 2.5-2.6 gph and the engine still lives...knocki
ng on wood!=0A=0ALynn Matteson=0AKitfox IV Speedster, taildragger=0AJabiru
2200, #2062=0APrince prop 64 x 30, P-tip=0AElectroair direct-fire ignition
system=0ARotec TBI-40 injection (sleeved to 36mm)=0AStatus: flying with 133
=========================0A
- - - - - - - - - - - - - -Matt Dralle, List Adm
=====
Message 3
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| Subject: | Re: Newest GAMI lean test...probably off-topic for |
most
Hi Marvin-
I wish I had taken better pictures, but these two pretty much show
what I did. When I was building it, I was thinking of having the
tubes go through a chamber that would have engine oil pumping through
it, but later decided against that and sawed off some of the "oil
box". In this picture, the box is still partly there. I would have
had to finish enclosing the box...a HUGE job, so I quit thinking
along those lines. The actual intake plenum is the trapezoid-shaped
box immediately in front of (to the left) the TBI. The rest of the
box...like where the bolt heads are showing, was to be the oil box.
This shot shows the basic tubes completed, and I'm just starting to
build the plenum box around the tubes. From looking at these shots, I
can see that I need to take some better pictures of the final product.
As far as the Gami lean test is concerned, you start with a rich
mixture, and then start to lean the engine in small increments,
according to the fuel flow meter, watching the EGT readouts. The
temperatures will rise as the engine is leaned, and then you will see
the EGT's reach a peak temperature, and further leaning will cause
the temperatures to start to drop. Normally this "peak and drop" will
happen one cylinder at a time, over the course of leaning in very
small increments....in my case I was leaning by 0.1 gph according to
the flow meter. When I did this test back in 2009 right after I
installed the TBI, (and using the original Jabiru manifold) the rear
two cylinders peaked first, then one of the fronts, and finally the
last one peaked. This was over the course of leaning that covered a
0.3 gph range. On a small engine like the Jabiru 4-cylinder, that
shows that the fuel distribution in the intake manifold is not real
good, but not terrible, either. But with the current manifold that I
built, the EGT's will peak, and the next 0.1 gph reduction in flow
(leaning), causes them all to start dropping right now. This shows
excellent fuel distribution according to the Gami method of lean
testing. The writings of people that I have read....John Deakin, Mike
Busch, to name a couple...say that most carbureted engines don't have
very good fuel distribution, so I'm pretty tickled with my results.
The address for the lean test is: http://www.gami.com/gamijectors/
leantest.php
Some interesting reading about engine operation is found in John
Deakin's writings. Here is the address for a complete index of his
articles, Pelican's Perch:
http://www.avweb.com/news/pelican/182146-1.html
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Prince prop 64 x 30, P-tip
Electroair direct-fire ignition system
Rotec TBI-40 injection (sleeved to 36mm)
Status: flying with 1336 hrs... (since 3-27-2006)
On Aug 22, 2012, at 11:03 AM, Marvin Williams wrote:
> OK Lynn, I'll bite. Tell us 'dummies' exactly how you performed
> your GAMI Lean Tests. Sounds interesting. Also, how about some
> photos of your latest intake system.
>
> Nice to hear from you.
>
> Marvin
>
Message 4
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| Subject: | Re: Newest GAMI lean test...probably off-topic for |
most
Marvin:
Read Here:
http://www.gami.com/gamijectors/leantest.php
Barry
On Wed, Aug 22, 2012 at 11:03 AM, Marvin Williams <marvinlnaz@yahoo.com>wrote:
> OK Lynn, I'll bite. Tell us 'dummies' exactly how you performed your GAMI
> Lean Tests. Sounds interesting. Also, how about some photos of your
> latest intake system.
>
> Nice to hear from you.
>
> Marvin
>
>
> ------------------------------
> *From:* Lynn Matteson <lynnmatt@jps.net>
> *To:* jabiruengines@yahoogroups.com; jabiruengine-list@matronics.com
> *Sent:* Wednesday, August 22, 2012 7:19 AM
> *Subject:* JabiruEngine-List: Newest GAMI lean test...probably off-topic
> for most
>
>
> I hadn't done a Gami Lean Test since I first installed my Rotec TBI back
> in 2009, and so yesterday and today I did another few tests. Back when I
> first installed the TBI, the Gami spread was 0.1 on one test, and two other
> tests showed a 0.3 spread. This was done using the Jabiru intake manifold
> and the rubber tube connecter. Thinking back, the 0.1 might have been a
> fluke, or bad reading. Since then, I had built three different intake
> manifolds out of aluminum tubing and plate, using different
> configurations...updraft, backdraft, etc. The latest manifold is a "ram
> induction" manifold with runners 19" long. I've had this one on for about
> 16 months.... 236 hours flying time. Because things were going well with
> this manifold, I had just forgotten about actually giving the engine the
> Gami lean test.
>
> Over the last two days, the tests, at 7000 feet yesterday, and 3300 feet
> today (MSL), all showed a spread of 0.1......from 2.8 gph to 2.7 gph at
> 2900 rpm and 7000 feet, and 3.4 to 3.3 gph at 2900 rpm at 3300 feet. During
> these tests, when going from one fuel flow reading to 0.1 less
> fuel...leaner....all four EGT readings would drop at the same time. They
> would be stabilized at one fuel flow setting, and about a half-turn of the
> vernier mixture knob, and all four would start dropping....every time. So
> this latest manifold is a keeper, as far as distributing fuel is concerned.
> And that is probably the reason that I can dawdle along, burning as low as
> 2.5-2.6 gph and the engine still lives...knocking on wood!
>
> Lynn Matteson
> Kitfox IV Speedster, taildragger
> Jabiru 2200, #2062
> Prince prop 64 x 30, P-tip
> Electroair direct-fire ignition system
> Rotec TBI-40 injection (sleeved to 36mm)
> Status: flying with 1336 hrs... - The JabiruEngine-List Email
> Forum -**http://www.matronics.com/Navigat= - MATRONICS WEB
> FORUMSList ===
>
>
> *
>
> *
>
>
Message 5
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| Subject: | Re: Newest GAMI lean test...probably off-topic for |
most
Glad to hear things are going well for you, Lynn. Others have not been so
lucky with the Rotec contraption. At least two other people that I know h
ave tried the Rotec and tossed it. Granted, it was the 3300 Jab, but the e
ngines never ran right and were not reliable enough to fly with.
To others who are considering the Rotec, be prepared to work your way thoug
ht some disappointment.
In my opinion.
Doug Koenigsberg
-----Original Message-----
From: Lynn Matteson <lynnmatt@jps.net>
Sent: Wed, Aug 22, 2012 1:54 pm
Subject: Re: JabiruEngine-List: Newest GAMI lean test...probably off-topic
for most
Hi Marvin-
wish I had taken better pictures, but these two pretty much show
hat I did. When I was building it, I was thinking of having the
ubes go through a chamber that would have engine oil pumping through
t, but later decided against that and sawed off some of the "oil
ox". In this picture, the box is still partly there. I would have
ad to finish enclosing the box...a HUGE job, so I quit thinking
long those lines. The actual intake plenum is the trapezoid-shaped
ox immediately in front of (to the left) the TBI. The rest of the
ox...like where the bolt heads are showing, was to be the oil box.
This shot shows the basic tubes completed, and I'm just starting to
uild the plenum box around the tubes. From looking at these shots, I
an see that I need to take some better pictures of the final product.
As far as the Gami lean test is concerned, you start with a rich
ixture, and then start to lean the engine in small increments,
ccording to the fuel flow meter, watching the EGT readouts. The
emperatures will rise as the engine is leaned, and then you will see
he EGT's reach a peak temperature, and further leaning will cause
he temperatures to start to drop. Normally this "peak and drop" will
appen one cylinder at a time, over the course of leaning in very
mall increments....in my case I was leaning by 0.1 gph according to
he flow meter. When I did this test back in 2009 right after I
nstalled the TBI, (and using the original Jabiru manifold) the rear
wo cylinders peaked first, then one of the fronts, and finally the
ast one peaked. This was over the course of leaning that covered a
.3 gph range. On a small engine like the Jabiru 4-cylinder, that
hows that the fuel distribution in the intake manifold is not real
ood, but not terrible, either. But with the current manifold that I
uilt, the EGT's will peak, and the next 0.1 gph reduction in flow
leaning), causes them all to start dropping right now. This shows
xcellent fuel distribution according to the Gami method of lean
esting. The writings of people that I have read....John Deakin, Mike
usch, to name a couple...say that most carbureted engines don't have
ery good fuel distribution, so I'm pretty tickled with my results.
The address for the lean test is: http://www.gami.com/gamijectors/
eantest.php
Some interesting reading about engine operation is found in John
eakin's writings. Here is the address for a complete index of his
rticles, Pelican's Perch:
http://www.avweb.com/news/pelican/182146-1.html
Lynn Matteson
itfox IV Speedster, taildragger
abiru 2200, #2062
rince prop 64 x 30, P-tip
lectroair direct-fire ignition system
otec TBI-40 injection (sleeved to 36mm)
tatus: flying with 1336 hrs... (since 3-27-2006)
n Aug 22, 2012, at 11:03 AM, Marvin Williams wrote:
> OK Lynn, I'll bite. Tell us 'dummies' exactly how you performed
your GAMI Lean Tests. Sounds interesting. Also, how about some
photos of your latest intake system.
Nice to hear from you.
Marvin
Message 6
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| Subject: | Re: Newest GAMI lean test...probably off-topic for |
most
I have been satisfied with my Rotec on theJabiru 3300.
Installation needs to be as specified.
Marvin
Sent from my "Geeky" iPhone
On Aug 22, 2012, at 2:02 PM, kayberg@aol.com wrote:
> Glad to hear things are going well for you, Lynn. Others have not been so
lucky with the Rotec contraption. At least two other people that I know h
ave tried the Rotec and tossed it. Granted, it was the 3300 Jab, but the en
gines never ran right and were not reliable enough to fly with.
>
> To others who are considering the Rotec, be prepared to work your way thou
ght some disappointment.
>
> In my opinion.
>
> Doug Koenigsberg
>
>
> -----Original Message-----
> From: Lynn Matteson <lynnmatt@jps.net>
> To: jabiruengine-list <jabiruengine-list@matronics.com>
> Sent: Wed, Aug 22, 2012 1:54 pm
> Subject: Re: JabiruEngine-List: Newest GAMI lean test...probably off-topic
for most
>
> Hi Marvin-
> I wish I had taken better pictures, but these two pretty much show
> what I did. When I was building it, I was thinking of having the
> tubes go through a chamber that would have engine oil pumping through
> it, but later decided against that and sawed off some of the "oil
> box". In this picture, the box is still partly there. I would have
> had to finish enclosing the box...a HUGE job, so I quit thinking
> along those lines. The actual intake plenum is the trapezoid-shaped
> box immediately in front of (to the left) the TBI. The rest of the
> box...like where the bolt heads are showing, was to be the oil box.
>
>
>
> This shot shows the basic tubes completed, and I'm just starting to
> build the plenum box around the tubes. =46rom looking at these shots, I
> can see that I need to take some better pictures of the final product.
>
> As far as the Gami lean test is concerned, you start with a rich
> mixture, and then start to lean the engine in small increments,
> according to the fuel flow meter, watching the EGT readouts. The
> temperatures will rise as the engine is leaned, and then you will see
> the EGT's reach a peak temperature, and further leaning will cause
> the temperatures to start to drop. Normally this "peak and drop" will
> happen one cylinder at a time, over the course of leaning in very
> small increments....in my case I was leaning by 0.1 gph according to
> the flow meter. When I did this test back in 2009 right after I
> installed the TBI, (and using the original Jabiru manifold) the rear
> two cylinders peaked first, then one of the fronts, and finally the
> last one peaked. This was over the course of leaning that covered a
> 0.3 gph range. On a small engine like the Jabiru 4-cylinder, that
> shows that the fuel distribution in the intake manifold is not real
> good, but not terrible, either. But with the current manifold that I
> built, the EGT's will peak, and the next 0.1 gph reduction in flow
> (leaning), causes them all to start dropping right now. This shows
> excellent fuel distribution according to the Gami method of lean
> testing. The writings of people that I have read....John Deakin, Mike
> Busch, to name a couple...say that most carbureted engines don't have
> very good fuel distribution, so I'm pretty tickled with my results.
>
> The address for the lean test is: http://www.gami.com/gamijectors/
> leantest.php
>
> Some interesting reading about engine operation is found in John
> Deakin's writings. Here is the address for a complete index of his
> articles, Pelican's Perch:
>
> http://www.avweb.com/news/pelican/182146-1.html
>
>
>
> Lynn Matteson
> Kitfox IV Speedster, taildragger
> Jabiru 2200, #2062
> Prince prop 64 x 30, P-tip
> Electroair direct-fire ignition system
> Rotec TBI-40 injection (sleeved to 36mm)
> Status: flying with 1336 hrs... (since 3-27-2006)
>
>
> On Aug 22, 2012, at 11:03 AM, Marvin Williams wrote:
>
> > OK Lynn, I'll bite. Tell us 'dummies' exactly how you performed
> > your GAMI Lean Tests. Sounds interesting. Also, how about some
> > photos of your latest intake system.
> >
> > Nice to hear from you.
> >
> > Marvin
> >
>
>
>
==========================
=========
==========================
=========
==========================
=========
==========================
=========
>
Message 7
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| Subject: | Re: Newest GAMI lean test...probably off-topic for |
most
Thanks Lynn and Barry.=0A=0AI assume that added volume in the intake system
is one of the reasons you have had success Lynn?- The Jabiru intake 'man
ifold' sure doesn't have the volume that it looks like yours has.- Seems
that your pipes to the heads are bigger also.- Am I wrong?=0A=0AI read th
e GAMI lean test article.- Seems to me that this test replaces the EGT sp
read criteria for proper cylinder balance.- Again, is that what you disce
rn?=0A=0AThe article talked about an engine having a fuel flow spread of .7
gph after GAMIs are installed.- I just wonder what the full fuel flow ra
te is?- If it's 15-17 GPH then the flow rate spread would be approximatel
y 5% of total flow rate.- I am no where smart enough to know what is good
and what isn't.- I'll just have to take the 'big boys' word for it.- B
ut I do find it interesting that EGT spread isn't talked about much anymore
.- Or did I just miss it?=0A=0AFWIW, I had GAMIs installed on my Mooney T
LS (TIO 540 as I recall) a long time ago.- For what it cost at the time,
I didn't think it was worth it.- I'll be quick to add that technology has
changed (improved) more than I know since then, and perhaps I myself am a
little (but not much) wiser now than I was then and it just might be that I
would recognize the improvement more now than then.- All conjecture obvi
ously.=0A=0AFortunately, now that I have been introduced to Fuel Spread tes
ts, I can easily run the test on our Jabiru 3300 with the engine analysis a
nd recording equipment we have, it should be a snap.- Fixing (or improvin
g) the issues will be the challenge.=0A=0AThanks again for the pictures and
your post!=0A=0AMarvin=0A=0A=0A=0A=0A________________________________=0A F
rom: Lynn Matteson <lynnmatt@jps.net>=0ATo: jabiruengine-list@matronics.com
=0ASent: Wednesday, August 22, 2012 10:46 AM=0ASubject: Re: JabiruEngine-L
ist: Newest GAMI lean test...probably off-topic for most=0A =0AHi Marvin-
=0AI wish I had taken better pictures, but these two pretty much show what
I did. When I was building it, I was thinking of having the tubes go throug
h a chamber that would have engine oil pumping through it, but later decide
d against that and sawed off some of the "oil box". In this picture, the bo
x is still partly there. I would have had to finish enclosing the box...a H
UGE job, so I quit thinking along those lines. The actual intake plenum is
the trapezoid-shaped box immediately in front of (to the left) the TBI. The
rest of the box...like where the bolt heads are showing, was to be the oil
box.=0A=0A=0A=0A=0A=0AThis shot shows the basic tubes completed, and I'm j
ust starting to build the plenum box around the tubes. From looking at thes
e shots, I can see that I need to take some better pictures of the final pr
oduct.=0A=0AAs far as the Gami lean test is concerned, you start with a ric
h mixture, and then start to lean the engine in small increments, according
to the fuel flow meter, watching the EGT readouts. The temperatures will r
ise as the engine is leaned, and then you will see the EGT's reach a peak t
emperature, and further leaning will cause the temperatures to start to dro
p. Normally this "peak and drop" will happen one cylinder at a time, over t
he course of leaning in very small increments....in my case I was leaning b
y 0.1 gph according to the flow meter. When I did this test back in 2009 ri
ght after I installed the TBI, (and using the original Jabiru manifold) the
rear two cylinders peaked first, then one of the fronts, and finally the l
ast one peaked. This was over the course of leaning that covered a 0.3 gph
range. On a small engine like the Jabiru 4-cylinder, that shows that the fu
el distribution in the intake manifold is not real good, but not terrible,
either. But with the current manifold that I built, the EGT's will peak, a
nd the next 0.1 gph reduction in flow (leaning), causes them all to start d
ropping right now. This shows excellent fuel distribution according to the
Gami method of lean testing. The writings of people that I have read....Joh
n Deakin, Mike Busch, to name a couple...say that most carbureted engines d
on't have very good fuel distribution, so I'm pretty tickled with my result
s.=0A=0AThe address for the lean test is:- http://www.gami.com/gamijector
s/leantest.php=0A=0ASome interesting reading about engine operation is foun
d in John Deakin's writings. Here is the address for a complete index of hi
s articles, Pelican's Perch:=0A=0Ahttp://www.avweb.com/news/pelican/182146-
1.html=0A=0A=0A=0ALynn Matteson=0AKitfox IV Speedster, taildragger=0AJabiru
2200, #2062=0APrince prop 64 x 30, P-tip=0AElectroair direct-fire ignition
system=0ARotec TBI-40 injection (sleeved to 36mm)=0AStatus: flying with 13
36 hrs... (since 3-27-2006)=0A=0A=0AOn Aug 22, 2012, at 11:03 AM, Marvin Wi
lliams wrote:=0A=0A> OK Lynn, I'll bite.- Tell us 'dummies' exactly how y
ou performed your GAMI Lean Tests.- Sounds interesting.- Also, how abou
t some photos of your latest intake system.=0A> =0A> Nice to hear from you.
=0A> =0A> Marvin=0A>
Message 8
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| Subject: | Re: Newest GAMI lean test...probably off-topic for |
most
That's too bad that those owners didn't have whatever it took to deal
with the proper installation, Doug. I've heard of a few who didn't
get it right the first time, but they got help, and are now flying
with it just fine. All these installations have to follow the
suggestions made by the factory...I'm wondering if they did?
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Prince prop 64 x 30, P-tip
Electroair direct-fire ignition system
Rotec TBI-40 injection (sleeved to 36mm)
Status: flying with 1336 hrs... (since 3-27-2006)
On Aug 22, 2012, at 5:02 PM, kayberg@aol.com wrote:
> Glad to hear things are going well for you, Lynn. Others have not
> been so lucky with the Rotec contraption. At least two other
> people that I know have tried the Rotec and tossed it. Granted, it
> was the 3300 Jab, but the engines never ran right and were not
> reliable enough to fly with.
>
> To others who are considering the Rotec, be prepared to work your
> way thought some disappointment.
>
> In my opinion.
>
> Doug Koenigsberg
Message 9
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| Subject: | Re: Newest GAMI lean test...probably off-topic for |
most
The larger plenum is probably part of the reason, Marvin. The tubes
are the same size as the original...1-1/4" O.D. I built the longer
tubes to take advantage of the "ram" effect, and that might be part
of the reason as well. Perhaps the longer tubes allow for more time
for the mixture to atomize, and this makes for a smoother-running
engine.
No, this is exactly the same test. All you are doing in this test is
verifying that the fuel flow difference between when the first
cylinder's EGT peaks, and the last cylinder's EGT peaks, is very,
very close. That determines how well the engine's air/fuel mixture is
distributed to the engine. If the first to peak is at say, 3.5 gph,
and the last to peak does so when the flow meter reads 3.0 gph,
that's a "GAMI spread" of a half-gallon per hour, and that is not
good distribution. If this were a direct-port injected engine, the
injector nozzles would be changed to bring the flow closer together
between the first, and the last, to reach peak EGT. This is what the
folks at GAMI do. But my engine, using a Rotec TBI, is basically a
carbureted engine, and you can't change individual nozzles like you
can with the direct-port engines.
The EGT spread is still talked about, but not the actual numbers from
what I've read. First you have to get the flow spread as close as
possible, then when that is done, then you can safely run lean of
peak EGT, knowing that each cylinder is enjoying very close to the
optimum share of the fuel/air mixture. If the flow spread is too far
off. some cylinders are too rich while others may be too lean, and
the engine will run roughly when leaned. And that's what all this is
about....being able to run LOP safely and comfortably. When the fuel-
flow spread is close, the EGT spread is close, and the CHT spread
will be close, and that is what makes for longer-lived engines.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Prince prop 64 x 30, P-tip
Electroair direct-fire ignition system
Rotec TBI-40 injection (sleeved to 36mm)
Status: flying with 1336 hrs... (since 3-27-2006)
On Aug 22, 2012, at 8:04 PM, Marvin Williams wrote:
> Thanks Lynn and Barry.
>
> I assume that added volume in the intake system is one of the
> reasons you have had success Lynn? The Jabiru intake 'manifold'
> sure doesn't have the volume that it looks like yours has. Seems
> that your pipes to the heads are bigger also. Am I wrong?
>
> I read the GAMI lean test article. Seems to me that this test
> replaces the EGT spread criteria for proper cylinder balance.
> Again, is that what you discern?
>
> The article talked about an engine having a fuel flow spread of .7
> gph after GAMIs are installed. I just wonder what the full fuel
> flow rate is? If it's 15-17 GPH then the flow rate spread would be
> approximately 5% of total flow rate. I am no where smart enough to
> know what is good and what isn't. I'll just have to take the 'big
> boys' word for it. But I do find it interesting that EGT spread
> isn't talked about much anymore. Or did I just miss it?
>
> FWIW, I had GAMIs installed on my Mooney TLS (TIO 540 as I recall)
> a long time ago. For what it cost at the time, I didn't think it
> was worth it. I'll be quick to add that technology has changed
> (improved) more than I know since then, and perhaps I myself am a
> little (but not much) wiser now than I was then and it just might
> be that I would recognize the improvement more now than then. All
> conjecture obviously.
>
> Fortunately, now that I have been introduced to Fuel Spread tests,
> I can easily run the test on our Jabiru 3300 with the engine
> analysis and recording equipment we have, it should be a snap.
> Fixing (or improving) the issues will be the challenge.
>
> Thanks again for the pictures and your post!
>
> Marvin
>
>
> From: Lynn Matteson <lynnmatt@jps.net>
> To: jabiruengine-list@matronics.com
> Sent: Wednesday, August 22, 2012 10:46 AM
> Subject: Re: JabiruEngine-List: Newest GAMI lean test...probably
> off-topic for most
>
> Hi Marvin-
> I wish I had taken better pictures, but these two pretty much show
> what I did. When I was building it, I was thinking of having the
> tubes go through a chamber that would have engine oil pumping
> through it, but later decided against that and sawed off some of
> the "oil box". In this picture, the box is still partly there. I
> would have had to finish enclosing the box...a HUGE job, so I quit
> thinking along those lines. The actual intake plenum is the
> trapezoid-shaped box immediately in front of (to the left) the TBI.
> The rest of the box...like where the bolt heads are showing, was to
> be the oil box.
>
> <100_1055.jpg>
>
>
> <100_4853.jpg>
>
>
> This shot shows the basic tubes completed, and I'm just starting to
> build the plenum box around the tubes. >From looking at these
> shots, I can see that I need to take some better pictures of the
> final product.
>
> As far as the Gami lean test is concerned, you start with a rich
> mixture, and then start to lean the engine in small increments,
> according to the fuel flow meter, watching the EGT readouts. The
> temperatures will rise as the engine is leaned, and then you will
> see the EGT's reach a peak temperature, and further leaning will
> cause the temperatures to start to drop. Normally this "peak and
> drop" will happen one cylinder at a time, over the course of
> leaning in very small increments....in my case I was leaning by 0.1
> gph according to the flow meter. When I did this test back in 2009
> right after I installed the TBI, (and using the original Jabiru
> manifold) the rear two cylinders peaked first, then one of the
> fronts, and finally the last one peaked. This was over the course
> of leaning that covered a 0.3 gph range. On a small engine like the
> Jabiru 4-cylinder, that shows that the fuel distribution in the
> intake manifold is not real good, but not terrible, either. But
> with the current manifold that I built, the EGT's will peak, and
> the next 0.1 gph reduction in flow (leaning), causes them all to
> start dropping right now. This shows excellent fuel distribution
> according to the Gami method of lean testing. The writings of
> people that I have read....John Deakin, Mike Busch, to name a
> couple...say that most carbureted engines don't have very good fuel
> distribution, so I'm pretty tickled with my results.
>
> The address for the lean test is: http://www.gami.com/gamijectors/
> leantest.php
>
> Some interesting reading about engine operation is found in John
> Deakin's writings. Here is the address for a complete index of his
> articles, Pelican's Perch:
>
> http://www.avweb.com/news/pelican/182146-1.html
>
>
> Lynn Matteson
> Kitfox IV Speedster, taildragger
> Jabiru 2200, #2062
> Prince prop 64 x 30, P-tip
> Electroair direct-fire ignition system
> Rotec TBI-40 injection (sleeved to 36mm)
> Status: flying with 1336 hrs... (since 3-27-2006)
>
>
> On Aug 22, 2012, at 11:03 AM, Marvin Williams wrote:
>
> > OK Lynn, I'll bite. Tell us 'dummies' exactly how you performed
> your GAMI Lean Tests. Sounds interesting. Also, how about some
> photos of your latest intake system.
> >
> > Nice to hear from you.
> >
> > Marvin
> >
>
>
Message 10
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| Subject: | Re: Newest GAMI lean test...probably off-topic for |
most
Doug:
It with tong in cheek, I have to laugh when you say "work your way
through". I joined the RATAX group to gain some insight. But, instead I
gained some track shoes to run away from RATAX as quick as possible. They
have so many problems it is amazing anyone would even consider that engine.
Yet, the they brag about the military using them on UAV's... Sure the
military can... They have unlimited funds to keep them running.
Barry
On Wed, Aug 22, 2012 at 5:02 PM, <kayberg@aol.com> wrote:
> Glad to hear things are going well for you, Lynn. Others have not been so
> lucky with the Rotec contraption. At least two other people that I know
> have tried the Rotec and tossed it. Granted, it was the 3300 Jab, but the
> engines never ran right and were not reliable enough to fly with.
>
> To others who are considering the Rotec, be prepared to work your way
> thought some disappointment.
>
> In my opinion.
>
> Doug Koenigsberg
>
>
> -----Original Message-----
> From: Lynn Matteson <lynnmatt@jps.net>
> To: jabiruengine-list <jabiruengine-list@matronics.com>
> Sent: Wed, Aug 22, 2012 1:54 pm
> Subject: Re: JabiruEngine-List: Newest GAMI lean test...probably off-topic
> for most
>
> Hi Marvin-
> I wish I had taken better pictures, but these two pretty much show
> what I did. When I was building it, I was thinking of having the
> tubes go through a chamber that would have engine oil pumping through
> it, but later decided against that and sawed off some of the "oil
> box". In this picture, the box is still partly there. I would have
> had to finish enclosing the box...a HUGE job, so I quit thinking
> along those lines. The actual intake plenum is the trapezoid-shaped
> box immediately in front of (to the left) the TBI. The rest of the
> box...like where the bolt heads are showing, was to be the oil box.
>
>
> This shot shows the basic tubes completed, and I'm just starting to
> build the plenum box around the tubes. From looking at these shots, I
> can see that I need to take some better pictures of the final product.
>
> As far as the Gami lean test is concerned, you start with a rich
> mixture, and then start to lean the engine in small increments,
> according to the fuel flow meter, watching the EGT readouts. The
> temperatures will rise as the engine is leaned, and then you will see
> the EGT's reach a peak temperature, and further leaning will cause
> the temperatures to start to drop. Normally this "peak and drop" will
> happen one cylinder at a time, over the course of leaning in very
> small increments....in my case I was leaning by 0.1 gph according to
> the flow meter. When I did this test back in 2009 right after I
> installed the TBI, (and using the original Jabiru manifold) the rear
> two cylinders peaked first, then one of the fronts, and finally the
> last one peaked. This was over the course of leaning that covered a
> 0.3 gph range. On a small engine like the Jabiru 4-cylinder, that
> shows that the fuel distribution in the intake manifold is not real
> good, but not terrible, either. But with the current manifold that I
> built, the EGT's will peak, and the next 0.1 gph reduction in flow
> (leaning), causes them all to start dropping right now. This shows
> excellent fuel distribution according to the Gami method of lean
> testing. The writings of people that I have read....John Deakin, Mike
> Busch, to name a couple...say that most carbureted engines don't have
> very good fuel distribution, so I'm pretty tickled with my results.
>
> The address for the lean test is: http://www.gami.com/gamijectors/
> leantest.php
>
> Some interesting reading about engine operation is found in John
> Deakin's writings. Here is the address for a complete index of his
> articles, Pelican's Perch:
> http://www.avweb.com/news/pelican/182146-1.html
>
>
> Lynn Matteson
> Kitfox IV Speedster, taildragger
> Jabiru 2200, #2062
> Prince prop 64 x 30, P-tip
> Electroair direct-fire ignition system
> Rotec TBI-40 injection (sleeved to 36mm)
> Status: flying with 1336 hrs... (since 3-27-2006)
>
>
> On Aug 22, 2012, at 11:03 AM, Marvin Williams wrote:
>
> > OK Lynn, I'll bite. Tell us 'dummies' exactly how you performed
> > your GAMI Lean Tests. Sounds interesting. Also, how about some
> > photos of your latest intake system.
> >
> > Nice to hear from you.
> >
> > Marvin
> >
>
>
> *
>
>
> *
>
>
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