---------------------------------------------------------- JabiruEngine-List Digest Archive --- Total Messages Posted Wed 08/22/12: 10 ---------------------------------------------------------- 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 _____________________________________ Time: 07:20:10 AM PST US From: Lynn Matteson 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... (since 3-27-2006) ________________________________ Message 2 _____________________________________ Time: 08:34:28 AM PST US From: Marvin Williams Subject: Re: JabiruEngine-List: 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 =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 =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 _____________________________________ Time: 10:53:41 AM PST US From: Lynn Matteson 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 > ________________________________ Message 4 _____________________________________ Time: 11:17:45 AM PST US Subject: Re: JabiruEngine-List: Newest GAMI lean test...probably off-topic for most From: FLYaDIVE Marvin: Read Here: http://www.gami.com/gamijectors/leantest.php Barry On Wed, 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 > > > ------------------------------ > *From:* Lynn Matteson > *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 _____________________________________ Time: 02:03:42 PM PST US Subject: Re: JabiruEngine-List: Newest GAMI lean test...probably off-topic for most From: kayberg@aol.com 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 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 _____________________________________ Time: 02:15:49 PM PST US Subject: Re: JabiruEngine-List: Newest GAMI lean test...probably off-topic for most From: Marvin 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 > To: jabiruengine-list > 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 _____________________________________ Time: 05:04:58 PM PST US From: Marvin Williams Subject: Re: JabiruEngine-List: 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 =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 _____________________________________ Time: 05:37:14 PM PST US From: Lynn Matteson Subject: Re: JabiruEngine-List: 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 _____________________________________ Time: 06:04:15 PM PST US From: Lynn Matteson Subject: Re: JabiruEngine-List: 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 > 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 ____________________________________ Time: 06:26:16 PM PST US Subject: Re: JabiruEngine-List: Newest GAMI lean test...probably off-topic for most From: FLYaDIVE 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, 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 > To: jabiruengine-list > 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 > > > > > * > > > * > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message jabiruengine-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/JabiruEngine-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/jabiruengine-list Browse Digests http://www.matronics.com/digest/jabiruengine-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.