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Yenn

Jabiru mixture

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Jabiru emailed me today touting their new mixture control. They have a you best electronic gadget that will inject air into each inlet manifold to ensure the mixture is correct for all stages of flight. It is fail safe they say.

 

Given that Jabiru have used the supposedly automatic mixture control carbide for years, are they saying that the carbide is not efficient, or not reliable? Either way I would rather replace the carbide with the injector produced for Stones.

 

 

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As a non Jab person, I always wondered about the ability of a single carburettor to deliver the same air/fuel mixture to  every combustion chamber  - particularly on the 6 cylinder models.

 

 

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As a non Jab person, I always wondered about the ability of a single carburettor to deliver the same air/fuel mixture to  every combustion chamber  - particularly on the 6 cylinder models.

 

 

 

Jabiru emailed me today touting their new mixture control. They have a you best electronic gadget that will inject air into each inlet manifold to ensure the mixture is correct for all stages of flight. It is fail safe they say.

 

Given that Jabiru have used the supposedly automatic mixture control carbide for years, are they saying that the carbide is not efficient, or not reliable? Either way I would rather replace the carbide with the injector produced for Stones.

 

No single  carb system delivers even fuel mixture to all cylinders. Even lycos and conts have uneven distribution. It’s just that they don’t measure it on most aircraft so you don’t know it, and they are big heavy cylinders which handle heat better so the cylinders don’t fail as much ( but still plenty do. ) if they are uneven so there isn’t the effort put to sort out uneven distribution cos it’s not as important. But jabs are really light, don’t have the heat sink capability of a massive amount of metal etc. so distribution becomes more important and more of us monitor  every cylinder for both CHT and EGT. 

 

Yenn - you are conflating two different issues. The carby is not unreliable and it’s reliability and function  is not affected or changed by the fuel control unit they’ve come up with. 

 

The carby does its bit more or less as its supposed to ( but personally I reckon it does it as marked but it’s a crap idea and I have long wished I had a normal carby that I could control leaning etc but that’s a different story. )

 

But the new control  unit  does all its stuff downstream of the carby and basically makes up for fact the mechanical pathway ( not the carby) stuffs up the work of the carby. It would be just fine if we had it feeding just one cylinder. 

 

What concerns me with the new system is it seems - maybe I’m wrong - that it relies on some cylinders running  rich  and then leans them match the leaner ones. 

 

Wonder how we deal with situation where none are rich  ( they’re just right say) and some are already lean. Then it leans out the just right ones  too make them lean to match the lean one. 

 

So now you run them all lean. 

 

So then you have to rejet the carby. Bigger job pulling carby out put it back retest it pull it out again if needed.  

 

Big job.  

 

 

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Soooooo! -  why not  scrap the carbi & install a fuel injection system ?

 

Cost predominantly. 

 

Jabiru sold engines with fuel injection to military customers  for a while so they have the technology. 

 

but it would cost more than they make to have the injection systems certified for use in manned aircraft. Theres less and less money in recreational aircraft and engines. And it’s being split up between more and more manufactures. 

 

If it’s not financially viable it won’t happen. 

 

 

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Cost predominantly. 

 

Jabiru sold engines with fuel injection to military customers  for a while so they have the technology... 

 

There is a significant market for fuel injection, so why not offer it as an option, to be fitted at the owner's risk?

 

I'd happily pay good money for a FI system that had been adapted to the Jab engine.

 

 

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There is a significant market for fuel injection, so why not offer it as an option, to be fitted at the owner's risk?

 

I'd happily pay good money for a FI system that had been adapted to the Jab engine.

 

Nothing is ever " at owners risk". 

 

There will always be a vulturous lawyer and an easily manipulated widow when these things go pear shaped.  It's amazing how the law so easily removes all fault from the dead victim and transfers it the living - especially if the living have deep pockets or are perceived to have deep pockets. 

 

 

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Nothing is ever " at owners risk". 

 

There will always be a vulturous lawyer ...

 

There's your first mistake, Jaba. A tautology.

 

With apologies to Kaz and any other ethical practitioners...

 

 

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There's your first mistake, Jaba. A tautology.

 

With apologies to Kaz and any other ethical practitioners...

 

Nah. I have to be careful and always adjectify that one. Have a number of mates ( one flying and two not) who slave at the coalface of the law so i have to be ever mindful of that. Just like I never assume all practitioners of my art are as altruistic as I am!  ??           ?

 

 

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There is a significant market for fuel injection, so why not offer it as an option, to be fitted at the owner's risk?

 

I'd happily pay good money for a FI system that had been adapted to the Jab engine.

 

Haltech could sell you a system if you fitted the necessary sensors, to them it would be just another 2.2l 4 cyl. Would it make the jab more reliable? I can't see it. Would it save 1-2 lph  maybe, it would be a long pay back. 

 

 

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Literally hundreds of millions of cars run on our roads utilising fuel injection - and have done for more than 40 years, in some cases.

 

Todays EFI is efficient, highly reliable, and a fuel-saver - and it's much more likely you would have a rotating/moving major engine component failure (valve, rings or piston), than an EFI component failure, if you had EFI fitted.

 

Carburettors may be very simple, but they are as anachronistic as wire strut wing supports, and bicycle wheels for undercarriage.  :stirrer:

 

 

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EFI

 

It has a limited fuel flow-through,

 

At 20 litres an hour most auto types would be past their capacity.

 

Big bore drag cars use carburetors to get the fuel "hundreds of litres per run" (650L,P,H,) to make their crazy horse-power.

 

" Under full throttle a modern top fuel dragster engine burns approx.11 gallons of fuel a minute. The fuel pump is capable of delivering 77 gallons per minute through a 2.5"diameter fuel line.

 

The fuel tank holds 17 gallons of fuel. A 55-gallon drum of nitromethane today costs about $900. "

 

Just a quick check, !

 

spacesailor

 

 

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I don't think I'll be needing 650l/h, Spacey. 

 

Those dragsters have almost nothing in common with the sort of power needs of our little planes.

 

 

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no more carb ice, less likely to burn out an exhaust valve, engine runs lean of peak all the time

 

 

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EFI

 

It has a limited fuel flow-through,

 

At 20 litres an hour most auto types would be past their capacity.

 

...........................................................................

 

spacesailor

 

This doesn't sound right to me -  Might be sort of right for smallish Euro/Asian engines but what about the big bore Yanks ?? (Yah I know the Euro's have a few  upmarket large capacity engines as well) A fuel injected 5-7 L is going to be able to turn mega litres of petrol into exhaust gas.

 

These days you just need a high pressure common rail system feeding  the electronic computer controlled injectors sing a fly by wire throttle and a few sensors so that the computer knows how much fuel to deliver ( did I make that sound easy or what?).

 

 

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Spacey, I don't think too many RA-Aus aircraft owners are into launching their aircraft skywards on takeoff, like an F-18 on full afterburners.  :laugh:

 

 

 

 

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You may be right

 

but

 

the bigger the equipment is, the bigger the DOLLAR sign.  ( never saw a High pressure rail like: ( 77 gallons per minute through a 2.5"diameter fuel line). that's about 10 times my 4 litre engine High-pressure rail.

 

77gal=291.477 litres: That wont fit through my high-pressure motor system. It wont even fit my fuel tank. LoL

 

spacesailor

 

 

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but it would cost more than they make to have the injection systems certified for use in manned aircraft. Theres less and less money in recreational aircraft and engines. And it’s being split up between more and more manufactures. 

 

 If it’s not financially viable it won’t happen. 

 

 

 

Nothing is ever " at owners risk". 

 

There will always be a vulturous lawyer and an easily manipulated widow when these things go pear shaped.  It's amazing how the law so easily removes all fault from the dead victim and transfers it the living - especially if the living have deep pockets or are perceived to have deep pockets. 

 

Well blow me away, a certified Jabiru engine? and “vulturous lawyers” Wat a combination. 

 

I did sum flying training up at a northern Victoria flying school about a year ago with a well respected CFI , nice chap, and the flying school Jabiru that I was flyin, I discovered was powered by the new generation engine. The engine was having a minor problem and that’s when I discovered that the engine was different to my Jabby engine. I made the comment that students, one who was me, are CRASH TEST DUMMYS. 

 

As I was paying muney to fly this aeroplane, where would I stand if I crashed this flying school aeroplane ???

 

Howcum Jabiru are using flying schools to test engines ??

 

I don’t think this is right, wat do you blokes recon ??

 

Ova to you. ....

 

 

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You may be right

 

but

 

the bigger the equipment is, the bigger the DOLLAR sign.  ( never saw a High pressure rail like: ( 77 gallons per minute through a 2.5"diameter fuel line). that's about 10 times my 4 litre engine High-pressure rail.

 

77gal=291.477 litres: That wont fit through my high-pressure motor system. It wont even fit my fuel tank. LoL

 

spacesailor

 

Cant say for sure as  you are quoting figures well outside my little experience. The thirstiest aircraft I ever flew cruised at around 32 L/hour and probably maxed out at take off power somewhere around 45-50L/hour (just guessing as this was all befor nice little electronic digital flow meters etc)

 

 

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Well blow me away, a certified Jabiru engine? and “vulturous lawyers” Wat a combination. 

 

I did sum flying training up at a northern Victoria flying school about a year ago with a well respected CFI , nice chap, and the flying school Jabiru that I was flyin, I discovered was powered by the new generation engine. The engine was having a minor problem and that’s when I discovered that the engine was different to my Jabby engine. I made the comment that students, one who was me, are CRASH TEST DUMMYS. 

 

As I was paying muney to fly this aeroplane, where would I stand if I crashed this flying school aeroplane ???

 

Howcum Jabiru are using flying schools to test engines ??

 

I don’t think this is right, wat do you blokes recon ??

 

Ova to you. ....

 

Not sure who or what have you the idea they are testing the engines for Jabiru. 

 

Thats just bollocks. 

 

 

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Well blow me away, a certified Jabiru engine? and “vulturous lawyers” Wat a combination. 

 

I did sum flying training up at a northern Victoria flying school about a year ago with a well respected CFI , nice chap, and the flying school Jabiru that I was flyin, I discovered was powered by the new generation engine. The engine was having a minor problem and that’s when I discovered that the engine was different to my Jabby engine. I made the comment that students, one who was me, are CRASH TEST DUMMYS. 

 

As I was paying muney to fly this aeroplane, where would I stand if I crashed this flying school aeroplane ???

 

Howcum Jabiru are using flying schools to test engines ??

 

I don’t think this is right, wat do you blokes recon ??

 

Ova to you. ....

 

The Jabiru airframe is among the most rigorously-tested and safest there is. Their engines are among the most reliable, as well as being the lightest and cheapest in their class.

 

If you want the (perceived) extra reliablity of Lycoming, Continental or Rotax, you'd have to pay double or more.

 

Ova to you...

 

 

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The Jabiru airframe is among the most rigorously-tested and safest there is. Their engines are among the most reliable, as well as being the lightest and cheapest in their class.

 

If you want the (perceived) extra reliablity of Lycoming, Continental or Rotax, you'd have to pay double or more.

 

Ova to you...

 

I agree on the airframe - top little aircraft BUT the engine !!??

 

Its great to support your motivation type but lets not get too carried away.

 

Reliability ? This sounds like you have been subjected to some pretty intensive mind altering the  therapy - I strongly doubt that, across the Jab engine fleet, their reliability can be compared to LyCon & Rotax.

 

As for cost: Yep ! they are a lot of engine for the purchase dollar but as with most things in life there is a down/flip side - you then pay in on going higher operating costs (save now pay later).

 

 

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...Reliability ? This sounds like you have been subjected to some pretty intensive mind altering the  therapy - I strongly doubt that, across the Jab engine fleet, their reliability can be compared to LyCon & Rotax.

 

As for cost: Yep ! they are a lot of engine for the purchase dollar but as with most things in life there is a down/flip side - you then pay in on going higher operating costs (save now pay later).

 

 Crickey Skip, it's been decades since any substances altered my mind! 

 

Seems that, in an effort to be economical with words, I have been less than clear. I wasn't saying the Jab engine is as reliable as the big three. I was saying it's not far behind and compares favourably with many, especially lots of cheaper engines.

 

I suspect many rec. airframes have to make comprises in structural robustness to accommodate the weight of the Rotax.

 

I'm a fan of the Jab engine for several reasons, including its simplicity. Without it my little plane would be handicapped with a low-powered, hand-started VW derivative.

 

 

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OR the little admired "HIRTH"

 

" The Hirth 3002, 80 HP, and 3003, 110 HP engines are unique in the industry. The are a four cylinder horizontally opposed air cooled engines. The 3002 is tuned for high torque, low rpm, and the 3003 is tuned for high horsepower. These engines are a great alternative to the Rotax 912 series engine"

 

Just googled & copied.

 

spacesailor

 

 

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Spacey, you forgot to mention the Hirth is little-admired, because it mostly converts gobs of fuel into lots of noise.  :cheezy grin:

 

 

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