Zenith Aircraft Builders and Flyers
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3300 low power ?
HiHo,
I suspect that my Jabiru 3300 motor is underpowered because it does not get up to the required RPM when stationary on the ground. I reach a maximum of 2100 rpm.
It has no measurable effect when using different propellers from the same manufacturer and identical length (Helix). I have tried propellers with 10, 11 and 12 degrees pitch and always the same effect, never more than 2200 rpm when standing on the ground.
Today I removed the air filter and the supply air now comes directly into the Bing carburetor, again without significant effect.
More RPM does not come from this.
It also doesn't matter if you turn on the additional electric fuel pump or not.
What else could it be and in what order do I best proceed to isolate the problem?
Too little fuel, possibly the wrong jetting, no or too little compression?
Does anyone have a suggestion for me please ?
Thank you and happy new year to you all.
Replies to This Discussion
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Permalink Reply by Shane Ballingall on
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My suggestion would be to speak to Jack Donsen at Topfun aviation - he has diagnosed and solved all the jabiru issues and now looks after a large fleet of engines.
there are several known issues with the Jabiru engines from the factory, including materials, pistons, loss of compression and failures in flight (I’ve had a complete engine failure on a jabiru 2200 before).
you can contact Jack at Topfun.net.au.
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Permalink Reply by Steffen Glatz on
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WILCO, thanks ...
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Permalink Reply by Don Burkholder on
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Any recent changes?
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Any recent changes, as I assume it was fine before....
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It was fine in test flights, not with me, but some hours later it is now the low power ....
I changed the run in oil to new shell .....
Still nothing ???
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What are the EGT's at wide open throttle? You should have about 1150F to 1250F
Did you verify that you have wide open at the Bing?
You said you removed the filter, did you remove the air connection at the inlet of the Bing and then tried?
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Yes, I removed all in front of the bing.
But I will follow your idea and inspect the bing from the air intake side on full throttle with an endoscope or mirror to verify if it is really fully open.
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You do not need anything to verify full throttle in cockpit equals throttle butterfly wide open. The Bing has a throttle blade, or butterfly, at the entrance and a controlling arm on the outside. Deeper inside the throttle bore is an air piston that varies it's opening based on the airflow your engine produces. Hence a constant velocity carburetor or CV Carb.
This piston has a tapered needle attached to the bottom that controls the volume of the fuel flowing through the needle jet or, main jet.
I would suspect that there is a restriction of fuel to the float bowl by means of an air leak on the suction side of the fuel pump or clogged fuel filter. This is one reason why I had a fuel pressure gauge on my 701 and found I had over the 3 psi maximum the Bing requires and made modifications to maintain constant 2 psi...
I suspect you are getting just enough fuel to allow a 3.3 liter engine to run 2100 rpm..
Too bad you don't live closer to Hershey Pa so I could help.
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That was my next suspect, that fuel flow might be to weak.
So I have to examine that ....
Will report ;-)
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What are the best working carburettor jets in the bing ?
I have to check that too.
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Permalink Reply by John Austin on
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How to jet the Bing: Tuning the Bing Carburetor on Jabiru Aircraft Engines.
John
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Or turn to the Sonex AeroInjector soon ... ?
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