Injection

[gwillimm]

looking at the XXXXX injection system has any one got it fitted to a 3300 jabiru engine and how did it improve the performance???

 

 

 

[Admin]

[Content removed]

 

Rotec have used this site in the past (in a manner that) caused them to be banned from here.

 

Post edited - Mod.

 

 

[gwillimm]

just need info??

 

:hittinghead:Where do u sudgest i get some honest infomation from??????

 

 

[Yenn]

There may be some info on homebuiltaeroplanes.com.

 

The XXXXX did get a mention on their forum a few weeks ago, but I havn't been following it.

 

 

[gwillimm]

Thanks Guys i will follow it up

 

Mick

 

 

[Captain]

Mick,

 

I was very interested to look at them if they can be proven to reduce CHT and EGT at equivalent or better performance and fuel usage.

 

But I will not take it further until there are heaps of favourable reports on their performance and reliability .... and even better would be an endoirsement from Jabiru (although that might be asking a bit much).

 

And I mean genuine fair-dinkum reports from multiple reputable owners with whom I can have a chat, and who are proven not to just be sudonyms of the manufacturer's employees, as appeared to be the case on this forum earlier this year.

 

On reflection after I saw them at Temora, I'm not sure I need an extra cable and mixture adjustment, nor to part with a $ grand, unless the performance and benefits are clearly demonstrated to be so great.

 

Regards Geoff

 

 

[gwillimm]

Jabiru injection

 

Thanks Geff for the reply i am still trying to find out as much info as i can before i Purchise one.

 

I am still doing my homework

 

Thanks MIck:hittinghead:

 

 

[cherk]

Jabiru injection;

 

Yahoo Jabiru engine group have users and lots of chattering re XXXXX,

 

............for what it's worth

 

 

[Steve Donald]

injection throttle body

 

looking at the XXXX injection system has any one got it fitted to a 3300 jabiru engine and how did it improve the performance???

Hiya yes i think it may prove a good system but XXXXX are expensive AERO VEE Make the same thing and is 1/3 the price, it has some very good reports,and has been and is being used on a number of Jab engines it would be worth a look and the company apparently are good to assist and provide all your needs, hope you have some luck cheers Steve

 

 

[Vorticity]

The aerocarb/aeroinjector uses a very different principle to that proposed by rotec. Have a read of the section regarding the aerocarb at Jeff Shultz's Sonex #0604 Building Log and then that at the rotec website. I think you will find some major differences.

 

 

[Admin]

I would 2nd that, Helmut did some incredible work on his Jab engine which has been going for quite a few years now - Helmut is on this site so send him a PM (hfrensch)

 

 

[facthunter]

Aero Carburetters-General.

 

I have a love hate relationship with all of them. IF you must use an Auto carb. the CV type is about the best as it does to a certain extent compensate for altitude. The common types are SU, Stromberg CD and the more common Bing.

 

To expect some marvellous improvement from fitting brand "X" over brand "Y" has been a common hope since the first carburetters were built.

 

They all mix petrol with air and if they are tuned right they do essentially the same job. Some have a slightly greater pressure drop as the air passes through them but the difference is not very much, not enough to go spending 1,000's of dollars for. Reliability is very important as a flooding carburetter can start an in flight fire. One of the worst things that can happen to you. The fact that petrol is evaporated inside them makes them prone to icing which is a nuisance and a serious safety consideration. A single carburetter installation or the Rotax set-up do not achieve even fuel distribution.

 

I do not like the aero-carb as it is floatless and any I have seen have been inclined to flood when starting if the thing is not sorted out and a good idle seem hard to achieve.

 

A simple fuel injection system would be the way to go. Even an adaptation of the drip system Used for the past 40 years in GA would be ok if done properly. Nev

 

 

[jetjr]

Even an adaptation of the drip system Used for the past 40 years in GA would be ok if done properly. Nev

 

Id guess thats what Jabiru are working on currently "maybe it will work, maybe it wont" says Rod

 

Theres a discussion on Yahoo Jab engines regarding interest in Kit EFI for Jab engines. US company SDS have most of the gear they are wondering how many are interested in complete kit - please register interest!!

 

 

[facthunter]

More.

 

I think it can be made to work. You have to run a pump but it does not have to be high pressure. probably engine driven, with one in the fuel tank for back-up. I also think that you could have a redundancy built into it, like a "manual mode'. where you can take control of it to get you home. I am old fashoned enough to want manual mixture control anyhow even with a Carby. Nev

 

 

[Vev]

I can’t say I love the Bing … the whole carby feels like a compromise of lesser evils and one tends to run the Bing mostly too rich to keep temps down across the working load range ... this is the only way to maintain acceptable levels on the hottest cylinder.

 

The idea of keeping things simple (no electronics) yet provide the pilot with the opportunity to adjust the mixture in flight is very appealing to me. It would be nice to be able to keep things rich and cool in climb and then adjust from your EGT readings to get set up for optimal cruise mixtures… currently with the Bing you end up with it too rich everywhere less you run the risk of burning a valve and cooking your top end.

 

I have had a look at the XXXXX, which looks like a copy of the Ellison TBI other than the regulator is remote, where the Ellison has the reg as an integrated part of the body. They both use a fuel bar which has many very small holes drilled along the delivery fuel tube (sometimes called a fuel bar) that becomes progressively exposed as a flat slide opens… the slide process is simular to a motorcycle slide on a 2 stroke carby. The fuel delivery volume is determined by the fuel bar position (which is controlled by rotating it ) and the angle of attack of the air passing through the throttle body…. By remotely (from the cockpit) rotating the fuel bar you change the mixture and set things up just where you want. The slide controls the volume of air entering the throttle body as well as exposing more of the delivery bar as it slides up. They both have a conventional idle circuit but they do need to be primed to get them to come to life as there is no fuel bowl to store fuel. I guess this is one of the real down sides of the TBI is one could over prime and end up with a lot of fuel over flow and increase the risk of fire at start up.

 

Intuitively (I’m guessing) the XXXXX approach may be slightly better at creating a more homogenous fuel/air distribution in the atomisation phase and therefore a reduction in the variations in CHT/EGT temps across the cylinders owing to a more even air/fuel mix… may be someone out there can verify or dismiss this my assumptions???

 

Personally I am still sitting on the fence and waiting to hear more reports from users and get some hard facts regarding performance before I dump the Bing…. However there are a lot of these out there, just not sure how many on Jabs and how they are going?

 

Cheers

 

Jack

 

 

[jetjr]

Evidence from users shows all the improvements from mixture control you stated however very little improvement in EGT spread so mixture control isnt able to achieve as much as hoped.

 

This possibly due to the issue being distribution problems downstream of carb, whatever brand

 

They are nicely made and do work but issues in Jab intakes still there.

 

Only solution I can see is port injection of some kind

 

 

[gwillimm]

Thanks for all your replies i have been getting much info as i can from the different forums. I am looking into fuel injection as well. Still studying

 

I will let you all now the out come.

 

Thanks

 

Mick

 

 

[Methusala]

G'day All,

 

I ran a VW conversion in my Volksplane with EFI based on original Bosch hardware off a 1600 TS and driven by a Haltech computer. Over 11 years I only had one problem which was related to a crook automotive spade type fuse. This was done by a relatively inexperienced amateur. I believe that someone could fashion a similar system for Jabiru. On the question of mixture, I had 2 egts and a 10k potentiometer that allowed me to alter the programmed mixture 10% either side so I did have the option if required. It ran all electrical demand off the simple alternater installed on the Aeropower. EFI is the best fuel metering system. Millions of cars prove the point. Don

 

 

[facthunter]

Convince me.

 

When you can park on a cloud and ring the NRMA I will accept that argument Don. I have had Sxxxloads of trouble over the years with EFI. At the power settings that aero engines run any error will hurt the engine. Mechanical systems can be finely calibrated and made fail safe. Some people may not like the need to manually lean the motor, but a flowmeter will take the guessmork out of it. Nev

 

 

[Methusala]

G'day All,

 

I'm just putting it out there as information. The system ran, as I said, without problems, needed no carburettor heat and through a manifold pressure meter, adjusted mixture automatically. The thing about EFI is that it can use the same electronic technology that we rely on to drive everything from pacemakers to fly by wire aeroplanes to deliver the precise amount of fuel needed to each cylinder. After all the reason for this thread is to investigate whether there is a better way to do things. Don

 

 

[facthunter]

Sensors.

 

Sure, Don and we all have different opinions. I'm only putting forward one.

 

You need a mass airflow figure and that is quite complex and normally there is a consideration of the amount of oxygen left in the exhaust gases, to fine tune it, (requires at least 3 sensors) ALL injection systems are an improvement icing wise on a carburetter and fuel distribution to individual cylinders is more even. The Jabiru has tried hard to get a manifold to be a good shape but (as has been pointed out) you never get even mixture distribution. You can do well with multiple carbs (ONE per cylinder) but aeroplanes should be simple. Especially ours, so we can build and service them, and have RELIABILITY. Often peak efficiency is sacrificed for reliability. The concept of redundancy is important too so you should have a "limp home" mode. This is not hard to arrange with a manual control base. I like to give myself a fighting chance. Nev

 

 

[Methusala]

Yes but....

 

G'day again. Seriously, I wonder how many incidents that we see called "landing mishaps" are related to induction icing? A friend of mine who is normally a very cautious pilot ended up tangled in a fence because he was approaching in a 503 powered plane on a trailing throttle and had unexpected sink just before the threshhold. When he eased the power lever forward the engine didn't respond. Oh dear! I really appreciated the simplicity of not havingthat carby heat control to worry about. And then there is mixture... another one that had been done away with by clever electronics. Once upon a time cars had manual advance, mixture and the accelerator was on the steering wheel. We can do better than to simply not trust modern technology. Don

 

 

[Yenn]

Don

 

A lot of people subscribe to the theory that you won't get carby ice with a 2 stroke. I know it does happen and have landed in a paddock because of it. I don't thing the Rotec will be 100% free of the same problem. There must be a big cooling event as the fuel leaves the tube and evaporates.

 

There was a post a long while ago by someone who used to be chief experimental engineer with Mitsubishi Australia. He described how he had fitted injection to his Jabiru. I will see if I can find it as I think I saved it somewhere.

 

 

[facthunter]

Trusting modern technology.

 

I don't think that "I don"t trust modern technology" does justice at all to the position I am describing. Cars use their method of engine management to achieve a better pollution outcome. car engines idle, have stop-start situations and run cruise control with automatic transmissions. The throttle is working all the time, and rarely sits in one position for long. The average power output is not high so quite lean fuel/air ratios can be used, most of the time.

 

Aircraft use Take-off power where the engine(s) are run over-rich for a short period,(usually up to five minutes) and cruise , most of the time, where the engine is run at about 70% power at various chosen altitudes. The comparison with the car situation, has limited validity. An idle descent is not a good thing for piston engines, for many reasons, either. Nev

 

 

[gwillimm]

Still getting infomation

 

Thanks every body for your replies But is there some one out there who has the rotec system fitted to there plane and are you happy with it.:hittinghead:

 

Thanks Mick