Comment

Comment by Mark Ertz on March 14, 2011 at 10:50pm

Biggest reason for airbox is to take in outside air which is clean and cool.  Jabiru engines tend to leak exhaust at the pipe and muffler fitting. The inside of the cowl is generally warmer, too.  I got a Sonex friend who has trouble with inline filter getting dirty after 3 or 4 hours.  I ran my intake inside the first winter to avoid icing but I lost about 125 rpm.  *When you get the bing tuned it is a joy to fly with. 

Comment by Michael Herder on March 14, 2011 at 4:11pm

If the big headache here is the silly 90 degree bend right before the carb... Can anyone tell me why we aren't running a system with a cone shaped K&N filter attached directly to the bing with electric carb heat to prevent icing?

Is anyone running such a system with a 601 FWF kit, if so what are your results?

Does it even fit???? I know it looks like our nose gear might get in the way, I'd hate to have to do a taildragger conversion for this
http://www.esatclear.ie/~xair/jabiru%20carb%20heat.htm

Comment by Mark Ertz on March 14, 2011 at 10:09am

Understanding what your jabiru is telling you is like understanding women.  Until you get 50 plus hours on your bird the numbers will lie. Get the engine out of break in and then fine tune.  I did this dance.  First, what is your prop set up?  49 degrees is best(will turn 3300 rpm).  I use a 51 degree prop from sensenich (will turn 3100 rpm).  Can't say about the others.  #1 fix is get your intake smooth over the front sensors!

From your notes, this is my input.  Start by writing it down, the numbers will start all running together in your head after awhile.  Different altitude, different climate, different power settings make different numbers.  2, The Germany Bing Carby on your Ausy engine are unique and mostly misunderstood.  Sonex never figured it out.  Don't look at this carby like stateside systems.  The sensors that operate your mixture work together well when you get clean smooth air flow into the carby.  Changing to a smooth intake tube hose is required.  However, two things got to be right.  The sensors infront of the carby should be unblock from any hose edge or rough surface and the small hose most be fitted tight.  Next, stop the turbelance or rough flow of air crossing over those sensors.  After many tries, I put a divider vertically down the middle of the intake hose.  Got the ideal from this blog site and a 601 builder @ Oshkosh. 

Basically, cut some 6061 and stand it up in the intake hose.  I put a hose clamp in the corner around the outside to hold it in place.  This improved my EGTS, CHTS, static run up and my top rpm.  Do this first and then change jets if nessecary.  I cannot over state how important it is to get the intake right.  A lot of 601 / Jabiru pilots are operating at lower power settings because they do not get their intake correctly setup. 

Your Jabiru should be run @ cruise at about 2650 - 2850 rpm by design. Slower than that you should have bought a 80 hp jabiru and run it at 65 %.  The 3300 runs best @ 70% power which is circa 2700 rpm.  This is all prop related however.  Think of it as a trany on a car.  Change to gear ratio you change the rpm, speed and the load.

So, pull your intake hose and put the vertical divider in which smooths the air over the front sensors and lets your mixture system function correctly.  It is really easy.  I made my divider fit the length of the hose and made sure not to connect the sensors. 

Last, true understanding of the health of your engine is a combination of the following: Spark plug color, exhaust color, smoothness at all throttle settings, fuel burn, oil burn, belly exhaust stain, cht temps & egt temps preety much in that order.  Look for grey colors, smooth starting and running, 5 gph burn @ 2700 rpm w/ chts of 320s +/- and egts 1350 +/-.  All jabiru engines are not the same.  So, know the stated limits and stay below them.  Egts less than 1420 are ok.  Chts less than 356 are ok.  lower is better.

Last, climate, altitude, load are real important to the numbers.  Extreme cold or hot plays a different game for operations.  Just know that in my opinion, most 601s / jabirus are detuned and running fat.  Just finger their exhaust and you will see they are mostly black as coal.  Good Luck w/ your Jabiru & woman....    

   

Comment by Michael Herder on March 13, 2011 at 9:28pm

Fantastic information Stephen.  Ironic or uncanny that #5 is my problem child as was yours too. It's not extremely bad, but it's measurably warmer than the rest.  I could understand why 6 is running so cold, but you would think 5 would do better than 1 or 3.  I wish there was a way to "balance" like we do with HVAC systems.  Closing 1 damper to let more or less air in.  I will play with the divider.  For today's results tilting the carb definitely helped.  Turned out to be nice flying today, despite earlier winds. 

Comment by Stephen R. Smith on March 13, 2011 at 8:47pm

Michael,

Take a look at this blog post with pictures.

Jabiru 3300, Bing carburetor and air intake system on in the Zodiac XL

 

Steve

Comment by Ralph Sanson on March 13, 2011 at 4:36pm

as per Phill's comment  I run a vane assembly prior to the carb. originally (after trialling smmoth hose, cobra head f/glass and 4 vane temporary measures I built a tube with 6 vanes inside about 2" long and that has been OK ever since.

 

If you still have one bank lean, loosen the carb and tilt a few degrees rotating the bottom of the carb to the lean side.

 

Ralph

Comment by Phill Barnes on March 12, 2011 at 8:32pm

Hi Michael

The air inside the intake tube spirals and the scat tube would break it up with a lot of turbulence. So if you have added a nice clean tube the spiral will make it to the carby and get divided unevenly by the vane at the carby. What many have done is to add a vertical alloy vane inside the tube to straighten the air. Jabiru are brining out an intake tube and airbox kit for around $1000 AUD. It has a horizontal vane inside the intake tube so as not to divide the air inline with the vertical carby vane and favour on side. Long story short, cut a piece of .032" alloy to fit into the tube in the horizontal position. One of my friends here have installed a vertical vane in his rubber radiator hose used for intake and he achieves higher RPM than before. Quick and easy thing to trial so give a go and post your outcome. Please note that I am not gauranteeing that this is your problem but it sound like the problem many have had.

 

Phill

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