C/S prop installation on Jabiru 2200 &fuel injection

[lyle janke]

hi all 

 i think about these mods from time to time 

are any of you running a fuel injection system  which type ? was it worth the change ?

 has anyone tried a C/S prop conversion any benefits? which one did you use ?

there doesn`t seem to be the interest  in replacing the carburetor 

[tillmanr]

There is a form of fuel injection available for your motor.

[lyle janke]

i`m aware off the rotec  TBI system   there is another rather exotic system that the use in south africa 

[facthunter]

Any large volume fuel system with atomised mixture all through it is a potential Hazard. Look what happens when some earlier type LPG systems backfire. Vee blocks split and conrods get shortened/bent. Nev

[onetrack]

The SDS EFI is anything but simple. Do you really want this level of complexity on an RA aircraft? - let alone the cost.

 

http://www.sdsefi.com/jabiru.htm

[RFguy]

Lyle the CS prop question would need some context - airframe, max, min flying speeds, desire to get off small strips etc.  

The BING in the Jabiru works pretty well if aligned right and is simple... Just do the float bowl inspection regularly and keep fuel system clean... Did you sell your J120 ?

[lyle janke]

1 hour ago, RFguy said:

Did you sell your J120 ?

hi yes  the J120 is now with a new owner  near canberra  . i`m currently waiting for the arrival of a J160

 

1 hour ago, RFguy said:

Lyle the CS prop question would need some context -

i was always wondering if there was any benifits to fitting in place of the jabiru plastic offering which was an improvement on the wooden one .having the pitching better matched to the motor requirements  with a C/S type  in the various phases of the flight 

[Ian]

11 hours ago, onetrack said:

The SDS EFI is anything but simple. Do you really want this level of complexity on an RA aircraft? - let alone the cost.

 

For many people the answer is yes. Cost and effort is another manner.

It provides the following advantages

• effective control of the fuel ratio in each cylinder,
• the reliability of solid state ignition,
• programmable ignition advance,
• The ability to use features like oxygen sensors to automatically optimize combustion,
• Strong spark for better starting,
• Not having to get magnetos services every 500 hours,
• significantly lighter in weight.

Modern engines are more reliable and flexible than old engines because they use solid state technology with fewer moving parts.

By comparison, wouldn't it be nice to get rid of something as complex as this with many moving parts and possible failure modes

and this

[Methusala]

11 hours ago, onetrack said:

The SDS EFI is anything but simple. Do you really want this level of complexity on an RA aircraft

Fact that EFI is all but universal in the auto field and has been for 20 years answers this question. The number of problems apparent with Bing and Mikuni carbs speaks volumes for the 'yes' case. Electronic ignition is also preferred vis the electro-mechanical alternative. Conservatism rightly has its place in aviation but should not blind us to better alternatives.

[RFguy]

Lyle see how your J160 goes  I think, J160 is a spirited aircraft compared to J170.  Yeah the plastic prop was a good upgrade.

I'd only move to a CS prop for a J160  if I had a very small strip to get out of...  (or a 914 rotax) . and even then, the improvements are limited, you only have 80HP. (or is it the 6 cyl) ? If it is the 6 cyl or a 912/914 rotax, there is more horsepower to make better use of so CS might be useful.

 

IMO with the EFI in a J160 you'll gain complexity and nothing else

 

-glen

[Methusala]

See also JG3's posts on propeller comparisons.

[skippydiesel]

It might be wise to look at the cost V effect/benefit of a CS.

 

Cost; Likely to be in the $10 k area  -$2k +6k depending on supplier.

Effect/benefit; As mentioned mainly in take off performance, with some top end benefit. 

[Yenn]

The cost of Rotec would be less than $1000, but it is only injection by name alone. It is not a fuel injection system any more than a Bing carbie is.

I wonder if a constant speed prop for a Jab plane with a Jab engine would be much of an improvement as the engine is working fairly hard at any time. On my Corby it would be ridiculous as I would be able to go over Vne so easily.

[facthunter]

Jab Motors are a bit hard on props. The safest is a two blade of wood. It's got effectively a flywheel at each end and no harmonic balancer anywhere.  Nev

[scsirob]

If you want a Jabiru with proven EFI and electronic ignition, why not buy a UL-Power engine?

They are a bit more expensive but less so than a Jabiru engine plus all the gizmo's you want to add, plus the installation and tweak time.

 

[Thruster88]

I see that Trent Palmer has removed the constant speed propeller from his freedom fox bush plane and gone back to a simple ground adjustable. The downside must have been greater that the benefit in his case.

[RFguy]

The UL260i would be a good+suitable  upgrade to improve an 80HP powered jabiru aircraft like the J170. 

At 21k USD that's a competitive alternative to the 912ULS (about 24kUSD with most of the accessories you need) .

[Flightrite]

I bought my RA flying machines for simplicity. They are cheap to run and maintain with parts avail in a milk bar! I like to be able to fix it by the side of the road with fencing wire if need be👍KISS method, fancy gizmo’s buys a lot of fuel👍

[facthunter]

I guess it depends whether you want to fly or fiddle with a plane (and spend $$$'s) Well targeted maintenance is all you need to be SAFE.  IF fiddling be your thing , Play on. Maestro. . Nev

[kgwilson]

The Jabiru composite prop is made by Bolly. Jabiru set the pitch and specify it should not be modified. You can modify it though easily but if the aircraft is factory built there may be a problem legally there. Jabiru do not recommend any props for their engines other than their own but there are some thousands of Jabiru engined aircraft with all sorts of different props.

 

I installed a 60 inch 2 blade Bolly Bos5 which is/was their top of the range ground adjustable prop made to fit the 3300A engine and it was a quantum leap ahead of the old wooden prop I replaced. It took 4 adjustments before I got the pitch right for the sort of lying I do.

 

If you fly from a short strip tune the prop a bit finer to give better takeoff & climb performance. You may lose 4 or 5 knots from top speed but who flys around flat out all the time anyway.

 

If you have plenty of runway length tune the prop to provide maximum continuous power in straight and level flight and this will provide the best economy at cruise settings and not overstress the engine.

 

Regardless of all this tune the prop for the sort of flying you do.

 

A constant speed or in flight adjustable will possible provide a small advantage but the disadvantages of extra weight, complexity and huge cost outweigh that by a considerable margin.

 

From what I have heard the TBI Rotec system provides little if any benefit and a full electronic injection system is going to cost an arm and a leg if you can even source one and get it working properly. Rod Stiff has been asked on numerous occasions about injection and the answer is always No for many reasons including cost, complexity and reliability.

[facthunter]

Jabiru have always warned of over propping which LUGS the engine, Like as in overgearing, as well as reducing the take-off performance. The way aero engines operate,  a simple fuel injection system near each port  would suffice and reduce the risk of damage due backfiring in a fuel mixture laden manifold, Setting something up for traffic etc is another thing entirely with constant power changes and idling.. I don't  think people realise what engine damage can happen when an engine backfires at a high load.  Nev

[Flightrite]

I operate my Jab donks at full noise for no more than 20-30 secs, only on T/off, 2800 rpm max at any other time, I expect they’ll outlast me😂

Edited January 22, 2022 by Flightrite

[Old Koreelah]

12 hours ago, Thruster88 said:

I see that Trent Palmer has removed the constant speed propeller from his freedom fox bush plane and gone back to a simple ground adjustable…

One of our club members had no end of problems with his CS prop.
He made sure to select the fixed-pitch prop option on his next plane.

 

5 hours ago, facthunter said:

Jabiru have always warned of over propping which LUGS the engine, Like as in overgearing, as well as reducing the take-off performance...

I don't  think people realise what engine damage can happen when an engine backfires at a high load.

A well-respected LAME I know always advised overproping (and having a little carb heat all the time).

Lots of Jab owners are happy with the results.
The couple of cruise knots you lose are insignificant compared to a buggered engine.

[facthunter]

As a rough rule if your cruise speed is below 110 Kts you don't need CS or in flight adjustable. Weight, cost and complexity  are the downside. Schneider Trophy racing seaplanes had fixed pitch wooden props. I was very impressed with a kiev prop fitted to one plane a flew a bit. Wood is down a few % on efficiency because you can't thin the sections as well as composite.  I've flown U/Ls with CS and of course they perform better but the plane was fast and had retracts as well.  Nev

[skippydiesel]

2 hours ago, facthunter said:

As a rough rule if your cruise speed is below 110 Kts you don't need CS or in flight adjustable. Weight, cost and complexity  are the downside. Schneider Trophy racing seaplanes had fixed pitch wooden props. I was very impressed with a kiev prop fitted to one plane a flew a bit. Wood is down a few % on efficiency because you can't thin the sections as well as composite.  I've flown U/Ls with CS and of course they perform better but the plane was fast and had retracts as well.  Nev

If I recall Schneider Trophy racing seaplanes didn't need CS props because there is little limit/obstructions when taking off so climb performance (fine  pitch) is sacrificed for high speed cruise (course pitch)