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Mixture control

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air.guerner(at)orange.fr
Guest

Posted: Fri Dec 26, 2008 11:55 am Post subject: Mixture control

Ron, 

 You will be adding a complicated system to an  already complicated engine. I am afraid this will further reduce the  reliability of your engine. Dealing with this sort of experiment on the  ground (I mean on a car or a motorbike) is something. Doing it on an airplane is  another story, especially if you want to use your bird as a reasonably reliable  cross country machine.

 Just my personal opinion.

 Regards

 Remi

  

 

 	  Quote: 	
		  >>>>>>>>>>N4211W not flying  yet, but have and will install a mixture control on 914.

First off installed  will be a Split Second mixture display that is driven
	


by a Bosch O2 sensor  (will weld a bung on the muffler inlet just

downstream of  turbo).



Slight different install on 914 because of Turbo compared to  912/s, but

will use a needle valve to leak pressure from normal airbox  pressure side

of enrichment solenoid to manifold cross tube. The more I leak  the leaner

the mixture will be.



This will require a run of hose to  cockpit then to manifold cross tube, I

will use high temperature Viton  tubing.



I will slight richen mixture on main jet and perhaps even jet  needle, I

always like to run slight rich when you are making a lot of BTUs  such as

100% power or in 914s case War emergency of 115%. It can also cool  things

a little on a hot engine (including when stuck on ground).



Then  will size a restriction on the controlled "leak" to manifold cross

tube so it  will allow me to only lean to ~14.7 at 18K.



Then will have an emergency  "rich" button that will allow me to activate

enrichment solenoid that could  further richen mixture on less than War

emergency power if I wish. In  addition the emergency "rich" button will

completely bypass all my additional  plumbing.



For either a 912/S or 914 install, if you at cruise power if  you pull

throttle without closing off your controlled leak, your engine is  probably

going to quit. On the other hand, if you set mixture at lets say 60%  power

and adjust mixture, if you increase power you will go richer than  probably

desired.



Another problem is if you lean at altitude, when you  come down things will

lean up further.



Having a Split Second display  is a nice tool for this control, a EGT

(which I have one on each side of  motor) is only semi useful.



HAC has or had a altitude adjusting bellows,  I would rather have full

manual control.



I am a motorhead and feel  very comfortable fiddling with carburation. If

you can't tune a lawnmower  engine to perfection by ear, owned a hot 2

stroke cycle that you managed to  run on the edge for long periods without

blowing up, probably not worth  considering the controlled 'leak' method of

adjusting Type 64 constant  depression carbs.



Ron  P.>>>>>>>>>>>>

    [quote][b]

terrys(at)cisco.com
Guest

Posted: Mon Jan 05, 2009 9:27 am Post subject: Mixture control

Hi Remi,

  

    We are members of the Experimental  Aircraft Association who have built an 'experimental aircraft'.  As such,  among other things not included in our standard kit, we have installed a mixture  control on our 912S which bleeds manifold pressure back into the carb bowl  vents.  Testing has shown that the standard rotax carb settings are  actually lean-of-peak at sea level on the front two cylinders and that it (of  course) gets richer with altitude, passing thru peak and on down the richer side  of peak EGT with increasing altitude.  It is our assumption that it is  acceptable for them to run the engines this way (lean of peak at take off)  because the heads are liquid cooled.

    We believe it is then a fair assumption  that we can run the engine lean-of-peak at altitude and <75% power, given  that the factory settings run the engine lean-of-peak at full power/sea  level.  Of course we monitor our exhaust, head, water, and oil temps just  to make sure everything is happy while leaning at altitude.

  

 regards,

 Terry Seaver

 A135/N135TD

 Monowheel XS, 912S, Airmaster  prop



   From: owner-europa-list-server(at)matronics.com  [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Remi  Guerner

Sent: Friday, December 26, 2008 11:53 AM

To:  Europa-List Digest Server

Subject: Mixture  control

 

 Ron, 

 You will be adding a complicated system to an  already complicated engine. I am afraid this will further reduce the  reliability of your engine. Dealing with this sort of experiment on the  ground (I mean on a car or a motorbike) is something. Doing it on an airplane is  another story, especially if you want to use your bird as a reasonably reliable  cross country machine.

 Just my personal opinion.

 Regards

 Remi

  

 

 	  Quote: 	
		  >>>>>>>>>>N4211W not flying  yet, but have and will install a mixture control on 914.

First off installed  will be a Split Second mixture display that is driven
	


by a Bosch O2 sensor  (will weld a bung on the muffler inlet just

downstream of  turbo).



Slight different install on 914 because of Turbo compared to  912/s, but

will use a needle valve to leak pressure from normal airbox  pressure side

of enrichment solenoid to manifold cross tube. The more I leak  the leaner

the mixture will be.



This will require a run of hose to  cockpit then to manifold cross tube, I

will use high temperature Viton  tubing.



I will slight richen mixture on main jet and perhaps even jet  needle, I

always like to run slight rich when you are making a lot of BTUs  such as

100% power or in 914s case War emergency of 115%. It can also cool  things

a little on a hot engine (including when stuck on ground).



Then  will size a restriction on the controlled "leak" to manifold cross

tube so it  will allow me to only lean to ~14.7 at 18K.



Then will have an emergency  "rich" button that will allow me to activate

enrichment solenoid that could  further richen mixture on less than War

emergency power if I wish. In  addition the emergency "rich" button will

completely bypass all my additional  plumbing.



For either a 912/S or 914 install, if you at cruise power if  you pull

throttle without closing off your controlled leak, your engine is  probably

going to quit. On the other hand, if you set mixture at lets say 60%  power

and adjust mixture, if you increase power you will go richer than  probably

desired.



Another problem is if you lean at altitude, when you  come down things will

lean up further.



Having a Split Second display  is a nice tool for this control, a EGT

(which I have one on each side of  motor) is only semi useful.



HAC has or had a altitude adjusting bellows,  I would rather have full

manual control.



I am a motorhead and feel  very comfortable fiddling with carburation. If

you can't tune a lawnmower  engine to perfection by ear, owned a hot 2

stroke cycle that you managed to  run on the edge for long periods without

blowing up, probably not worth  considering the controlled 'leak' method of

adjusting Type 64 constant  depression carbs.



Ron  P.>>>>>>>>>>>>

[quote]



href="http://www.matronics.com/contribution">http://www.matronics.com/chref="http://www.matronics.com/Navigator?Europa-List">http://www.matronhref="http://forums.matronics.com">http://forums.matronics.com

[b]

air.guerner(at)orange.fr
Guest

Posted: Tue Jan 06, 2009 3:00 am Post subject: Mixture control

Hi Terry,

  

 That interesting information. I am not surprised to  learn that the engine is running lean of peak at sea level, even at full power,  as this is consistent with the specific fuel consumptions advertised by  Rotax.

 I am interested in knowing more about your mixture  control system.

 My concern is about the reliability of this system  as you are adding piping from the engine to the cockpit and a sort of tap  to control the leak I suppose. What happens if one of the pipe connections leaks  or breaks? What are the effect of advancing or retarding the throttle if you  forget to enrichen first? Does that kill the engine?  

 Regards

 Remi

  

  

  

  

  

 

 	  Quote: 	
		  >>>>   We are members of the Experimental  Aircraft Association who have

built an 'experimental aircraft'.  As  such, among other things not
	


included in our standard kit, we have installed  a mixture control on our

912S which bleeds manifold pressure back into the  carb bowl vents.

Testing has shown that the standard rotax carb settings are  actually

lean-of-peak at sea level on the front two cylinders and that it  (of

course) gets richer with altitude, passing thru peak and on down  the

richer side of peak EGT with increasing altitude.  It is our  assumption

that it is acceptable for them to run the engines this way (lean  of peak

at take off) because the heads are liquid cooled.

   We  believe it is then a fair assumption that we can run the engine

lean-of-peak  at altitude and <75% power, given that the factory settings

run the engine  lean-of-peak at full power/sea level.  Of course we

monitor our exhaust,  head, water, and oil temps just to make sure

everything is happy while  leaning at altitude

 regards,

Terry  Seaver<<<<<<<<<<<



    [quote][b]

terrys(at)cisco.com
Guest

Posted: Tue Jan 06, 2009 9:49 am Post subject: Mixture control

Hi Remi,

  

 As I recall, we installed the Green Sky HACman mixture control system, see their  URL at;

 http://www.greenskyadventures.com/bing/HACmandetails.htm 

  

 Since we already had manifold  pressure (vacuum) behind our panel  (for the MP pressure transducer) it was only one additional line back to the  carb bowl vents to implement. My partner in the plane, Dave DeFord, is the one who did  most of the installation and testing,  so he knows it better than I do.  We use the mixture control on longer trips at altitude.   You would want to use the EGT on a  front cylinder to set lean-of-peak mixture (since  the front cylinders run leaner the the rear), although just leaning until  the engine gets rough and then richening  up a little also works just fine (like I used to do with the Cessna  152).  It does work better with the throttle closed just a little, but may work some even at full  throttle, I don't quite remember that part.  The engine can be expected to  run rough if you close the throttle and/or descend, but I don't ever remember it  actually dying.  Any aircraft will run rough if you descend without  readjusting the leaned mixture, so this is really not all that different, and  you are unlikely to close the throttle for any other reason than descending, are  you?

  

 I am not sure the  leaning mechanism has enough 'authority' to actually kill the engine, I will  check with Dave later tonight to see if he recalls testing for  that.

  

 regards,

 Terry  Seaver

   From: owner-europa-list-server(at)matronics.com  [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Remi  Guerner

Sent: Tuesday, January 06, 2009 2:58 AM

To:  Europa-List Digest Server

Subject: Mixture  control

 

 Hi Terry,

  

 That interesting information. I am not surprised to  learn that the engine is running lean of peak at sea level, even at full power,  as this is consistent with the specific fuel consumptions advertised by  Rotax.

 I am interested in knowing more about your mixture  control system.

 My concern is about the reliability of this system  as you are adding piping from the engine to the cockpit and a sort of tap  to control the leak I suppose. What happens if one of the pipe connections leaks  or breaks? What are the effect of advancing or retarding the throttle if you  forget to enrichen first? Does that kill the engine?  

 Regards

 Remi

  

  

  

  

  

 

 	  Quote: 	
		  >>>>   We are members of the Experimental  Aircraft Association who have

built an 'experimental aircraft'.  As  such, among other things not
	


included in our standard kit, we have installed  a mixture control on our

912S which bleeds manifold pressure back into the  carb bowl vents.

Testing has shown that the standard rotax carb settings are  actually

lean-of-peak at sea level on the front two cylinders and that it  (of

course) gets richer with altitude, passing thru peak and on down  the

richer side of peak EGT with increasing altitude.  It is our  assumption

that it is acceptable for them to run the engines this way (lean  of peak

at take off) because the heads are liquid cooled.

   We  believe it is then a fair assumption that we can run the engine

lean-of-peak  at altitude and <75% power, given that the factory settings

run the engine  lean-of-peak at full power/sea level.  Of course we

monitor our exhaust,  head, water, and oil temps just to make sure

everything is happy while  leaning at altitude

 regards,

Terry  Seaver<<<<<<<<<<<



[quote]



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href="http://www.matronics.com/contribution">http://www.matronics.com/c

[b]

gregoryf.flyboy(at)comcas
Guest

Posted: Sat Jan 10, 2009 9:09 pm Post subject: Mixture control

Terry,  

   

I like the idea of compensating the Bing carbs which would tend to run rich at high altitudes, anyway.  

Are you flying yet? Ie: Have you flown this arrangement, to see how well it worked, or how much fuel was being saved?  

   

Thanks in advance,  

Greg Fuchs, A050  

   

   

   

Hi Remi,  

   

   We are members of the Experimental Aircraft Association who have built an 'experimental aircraft'.  As such, among other things not included in our standard kit, we have installed a mixture control on our 912S ……….snip….  

regards,  

Terry Seaver  

       

  

       [quote][b]

terrys(at)cisco.com
Guest

Posted: Mon Jan 12, 2009 10:02 am Post subject: Mixture control

Hi Greg,

  

 We have been flying over 7 years, but only about one  year since installing  the mixture control.  My partner, Dave DeFord  did most of the testing, so he knows the specifics better than I do.  As I  recall, we can reduce fuel flow 5+%, at altitudes of 8000-10000 feet.  It  doesn't work well at full throttle, because it requires a pressure difference  across the carb butterfly to work.  This means it is less effective at very  high altitudes where you would need full throttle to get to cruise  power.

  

 The device we used is the Green Sky HACman mixture control  system, see their URL at; http://www.greenskyadventures.com/bing/HACmandetails.htm 

  

 regards,

 Terry Seaver

 A135/N135TD

   From: owner-europa-list-server(at)matronics.com  [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Greg Fuchs  

Sent: Saturday, January 10, 2009 9:06 PM

To:  europa-list(at)matronics.com

Subject: RE: Mixture  control

 

  

Terry, 

  

I like the idea of  compensating the Bing carbs which would tend to run rich at high altitudes,  anyway. 

Are you flying yet? Ie:  Have you flown this arrangement, to see how well it worked, or how much fuel was  being saved? 

  

Thanks in  advance, 

Greg Fuchs,  A050 

  

  

  

Hi  Remi, 

  

   We are  members of the Experimental Aircraft Association who have built an 'experimental  aircraft'.  As such, among other things not included in our standard kit,  we have installed a mixture control on our 912S ……….snip…. 

regards, 

Terry  Seaver 

    



[quote]



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href="http://www.matronics.com/contribution">http://www.matronics.com/c

[b]

air.guerner(at)orange.fr
Guest

Posted: Mon Jan 19, 2009 12:56 pm Post subject: Mixture control

Terry,

  

 I am coming back to this subject as I am doing some  maintenance on the engine and had to remove the exhaust system. I took this  opportunity to look at the coloration inside the exhaust elbows. Here is what I  found:

 Cyl 1: black

 Cyl 4: white

 Cyl 2 and 3: light brown

  

 So cyl 4 is the leanest on my engine. Cyl 1 is the  richest and the other 2 are in between.  My engine has 350 hours and no  adjustment of the carb needles were done since new. I could adjust the right  carb needle to run leaner on Cyl 1 and 3, but the two front cylinders (1 and 2)  would still run richer than the rear ones. This is different from what you  experienced with your own engine. Mixture maldistribution is obvious here and  does not seem to be repeatable on all engines of the type (912  ULS).

  

 Regards

  

 Remi Guerner

 F-PGKL

  

  

  

  >>>>>>>Testing has shown  that the standard rotax carb settings are actually lean-of-peak at sea level on  the front two cylinders <<<<<<<<

Terry Seaver  



    [quote][b]

grahamsingleton(at)btinte
Guest

Posted: Mon Jan 19, 2009 3:55 pm Post subject: Mixture control

Remi Guerner wrote:

 	  Quote: 	
		   Terry,

  

 I am coming back to this subject as I am doing some maintenance on the 

 engine and had to remove the exhaust system. I took this opportunity 

 to look at the coloration inside the exhaust elbows. Here is what I found:

 Cyl 1: black

 Cyl 4: white

 Cyl 2 and 3: light brown

  

 So cyl 4 is the leanest on my engine. Cyl 1 is the richest and the 

 other 2 are in between.  My engine has 350 hours and no adjustment of 

 the carb needles were done since new. I could adjust the right carb 

 needle to run leaner on Cyl 1 and 3, but the two front cylinders (1 

 and 2) would still run richer than the rear ones. This is different 

 from what you experienced with your own engine. Mixture 

 maldistribution is obvious here and does not seem to be repeatable on 

 all engines of the type (912 ULS).

  

 Regards

  

 Remi Guerner

 F-PGKL

Remi
	


the inlet to the carbs can have a marked effect. Some friends were 

struggling with a Jab6 installation, single Bing carb, the rear 

cylinders were overheating. After many fruitless efforts with cooling 

baffles over a frustrating year, the cure was to replace the nice smooth 

elbow at the inlet with a square box. Courtesy of Tony Higgins experience.

Graham

rparigor(at)suffolk.lib.n
Guest

Posted: Mon Jan 19, 2009 5:33 pm Post subject: Mixture control

Hi Remi



First and foremost you don't want to be running lean when you are making "a lot" of BTUs.



Make sure your carb jets and passages are not clogged with "carb snot" and your diaphragm is not ripped or torn.



If your forward cylinders run a little rich at lower RPMs, so be it, but at take off power your real interest is you are not running lean at all. Best taint slight towards richer at full power. Rotax has you check older 914s and newer ones with intake modifications (intercooler is a intake modification for carbon monoxide content and list a minimum, in other words they want to make sure you are rich enough at higher power settings. Pay very careful attension that you are not lean at high power.



Then lower power settings, I am an advocate to run them to point where engine does not hesitate. After carbs are verified "OK" and you sync them, you can fool with airscrew adjustment, turning in richens mixture and out leans them up. Go a little at a time until engine hesitates then go a bit richer. This is only going to be in effect at idle and not much over. Black can accumulate from lower speed operations. 



*Thus go over carbs and connections with a fine tooth comb

*Verify at 105% and at 85% you are not too lean on any cylinder, easier said than done, if you have EGTs you can temporarily turn off fuel and see if you ar rich of peak, if you don't get a rise, you may be lean or even lean of peak, running peak and lean of peak at high power settings goes against long engine life

*Cruise is where you spend most of your time, thus remember that running mogas does not give a very good inducation of mixture on plugs, run some 100LL and cruise and land as quick as possible and take a plug reading, see what things look at.  You can take a plug reading then at taxi power settings and see what that looks like. A bit hard on motor but to take a good full power plug reading, you would need to have full power for a while, then turn off motor after not too long a cool down and take a reading. Unless a Tri or Mono glider you best not want to a deadstick on a Mono short wing?



Ron P.

Visit -  www.EuropaOwners.org

air.guerner(at)orange.fr
Guest

Posted: Tue Jan 20, 2009 2:35 am Post subject: Mixture control

Graham,

  

 I agree that the inlet configuration is important.  As I am using the Rotax 912 series optional airbox, this may be the cause of the  different mixture distribution compared to the same engine type fitted with the  Europa airbox.  

  

 Remi 

  

  

 

the inlet to the carbs can have a marked effect. Some friends were  

struggling with a Jab6 installation, single Bing carb, the rear  

cylinders were overheating. After many fruitless efforts with cooling  

baffles over a frustrating year, the cure was to replace the nice smooth  

elbow at the inlet with a square box. Courtesy of Tony Higgins  experience.

Graham

    [quote][b]

air.guerner(at)orange.fr
Guest

Posted: Tue Jan 20, 2009 2:54 am Post subject: Mixture control

Hi Ron,

  

 Better too rich than too lean, I  agree.

  

 Remi

  

  

  

 >>>>>>>>If your forward cylinders run a little rich  at lower RPMs, so be it, but at take

off power your real interest is you are  not running lean at all. Best taint

slight towards richer at full  power<<<<<<<<<

    [quote][b]

terrys(at)cisco.com
Guest

Posted: Tue Jan 20, 2009 9:18 am Post subject: Mixture control

Hi Remi,

  

 It is quite possible that I got the front and rear  mixtures mixed up.  I will check my notes when I get home tonight to see if  this is the case.  The point I was trying to make was  that;

 1) the intake manifold does not feed all cylinders  symmetrically, causing some to be leaner than others,

 2) The evidence suggests that on our 912S, the lean  cylinders start out lean of peak at see level.

  

 We believe this lean of peak is acceptable because the  heads are liquid cooled.

  

 regards,

 Terry



   From: owner-europa-list-server(at)matronics.com  [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Remi  Guerner

Sent: Monday, January 19, 2009 12:50 PM

To:  Europa-List Digest Server

Subject: Mixture  control

 

 Terry,

  

 I am coming back to this subject as I am doing some  maintenance on the engine and had to remove the exhaust system. I took this  opportunity to look at the coloration inside the exhaust elbows. Here is what I  found:

 Cyl 1: black

 Cyl 4: white

 Cyl 2 and 3: light brown

  

 So cyl 4 is the leanest on my engine. Cyl 1 is the  richest and the other 2 are in between.  My engine has 350 hours and no  adjustment of the carb needles were done since new. I could adjust the right  carb needle to run leaner on Cyl 1 and 3, but the two front cylinders (1 and 2)  would still run richer than the rear ones. This is different from what you  experienced with your own engine. Mixture maldistribution is obvious here and  does not seem to be repeatable on all engines of the type (912  ULS).

  

 Regards

  

 Remi Guerner

 F-PGKL

  

  

  

  >>>>>>>Testing has shown  that the standard rotax carb settings are actually lean-of-peak at sea level on  the front two cylinders <<<<<<<<

Terry Seaver  



[quote]



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[b]

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