New Jabiru Engine

[Guernsey]

concerning different carb set ups for Jabiru take a look at what sonex are doing with their installations, they claim to have much better fuel distribution with even temps. Their carbs are reasonable price too, be worthwhile for someone to give it a run. Tom

It may be a false claim, however, it is well worth investigating....nothing ventured, nothing gained.

 

Alan.

 

 

[Thruster87]

It may be a false claim, however, it is well worth investigating....nothing ventured, nothing gained.Alan.

There has been a lot of discussion at: http://forums.matronics.com/viewtopic.php?t=62232

 

 

[facthunter]

Had a look thanks T87. Nev

 

 

[eightyknots]

Given the lack of testing and development in the past I wouldn't touch any 'new' Jabiru development till some other mug has put 1000 hrs on it. Normally you would expect an engine manufacturer to do that sort of testing themselves but we all know that Jabiru's test program is carried out by the folk who buy their engines. The same folk that regret it later.

I think they borrowed the customer-will-test-the-product concept from Microsoft.

 

 

[Dieselten]

Just my personal opinion:-

 

Changing the material of the cylinders to aluminium and using longer through-bolts will have most likely cause major changes in the resonances and vibrational nodes in the engine, from the crankcase right through to the heads, valves and everything in the chain. This effectively makes the engine a totally new engine and I just hope it is put through a complete re-testing and re-certification programme before it is unleashed on an unsuspecting public.

 

A case could be argued that the R&D dollars invested by Jabiru in this effort might have been better-spent doing the firewall-forward re-design for one of the Rotax 912/914 family of engines. At what point does a company cut its losses and go with a powerplant with a proven track-record instead of pouring precious man-hours and dollars into the unknown? Efforts such as this resulted in the bankrupting of Rolls Royce (the "Hyfil" fan-blades for the RB211 engine) and the British government had to bail the company out. Jabiru doesn't have pockets as deep as Rolls Royce had, and no Australian government is going to bail out a little company that sends itself broke.

 

Nobody wants to see Jabiru go to the wall or be taken over. None of us who own their products want to see our aircraft become orphans, bereft of spare-parts and technical support. We want Jabiru to be successful and stay around for a long time. But sooner or later someone in the company has to make the decision about whether it is appropriate to make the entire aircraft "in-house" or concentrate on the airframes and associated systems, leaving the engine to manufacturers whose track-record speaks for itself.

 

At the very least the factory might make a concession to reality and offer a choice of either their own engine, or the Rotax unit with a total firewall-forward package. Leaving third-parties to develop approved replacement conversions is just abrogating the responsibility of the manufacturer to produce the best product they can. It should not be necessary.

 

 

[winsor68]

Surely the factory realizes that there are growing numbers of pilots who have a Jabiru "no fly" policy whether justified or not.. Ra-aus will have to put it in the ops manual soon!!

 

 

[Powerin]

I just hope it is put through a complete re-testing and re-certification programme before it is unleashed on an unsuspecting public.

The current engine is certified....so certification is no guarantee. I don't know much about it, but it seems to me sometimes that certification exacerbates things. Once a manufacturer spends all the money and gets a design certified the design is set in stone and then they can't make any major changes without spending all the money to re-certify. Even if those changes would result in a safer product.

 

 

[facthunter]

Having a certified aviation product (Being a very costly process to achieve), makes modifying it more difficult and a case could be argued, for this being a less safe process than IF easily approved modes were more available. Some mods have been done to Jabirus over time, and I assume most of them are approved.

 

I wanted to install a throttle friction nut on the Citabria. Pretty much impossible to do legally, (and you wouldn't do it any other way). although just about all other aircraft have one.( problem with a certified aircraft)

 

An engine with through studs going right through to the heads, is another kettle of fish, but it's probably safer than relying on the tensile strength of the Al cylinders.

 

Alloy cylinders are fairly unusual on aircraft engines. Apart from thr Rotax (which is a quite small engine) the only one I know is the Franklin . The cylinders have to be quite "bulky" to have the strength in the Al and in the case of the Franklin have a pressed in cast iron liner, and integral cylinder head. There is probably little room on the jabiru crankcase for "bulky" cylinders

 

The new engine still has detachable cylinder heads which is still fairly rare in "mainstream" designs, which generally have a steel cylinder with a permanent( for all practical purposes) screwed and shrunk on alloy head which in some designs is forged. The head to cylinder joint is another thing to cause trouble and is better eliminated. Heat transfer is better if it is not there too, but servicing is a bit more difficult.

 

Steel is nowhere near as good a conductor of heat as aluminium is .

 

Jabiru markets engines for fitment to other aircraft besides their own. They are entitled to try to get a better result, and the purchaser is entitled to want to be convinced before he/she buys.

 

A "new" design can cause problems, but so can just changing the supplier of a part or billet of material. Hope they are successful. It's a market I wouldn't want to be in. (Though I have thought of building a couple of engines of my own, just for the fun of it)

 

They had a contest in the USA in the 20's where one of the criteria was that a motorcycle engine had to be used to power it. Nev

 

 

[geoffreywh]

Good to see Jabiru still investing in local manufacturing. Nikasil should be an improvement, and stop the rusting bores problem (I have to remember to run my engine on a weak 2-stroke mix before a long period of inactivity).Tough stuff, that Nicasil. When my wife's 1978 Guzzi was assembled they couldn't even get within the incredibly sloppy tolerances typical of Italian manufacturing at the time. The crank had so much movement the rings somehow chewed out the top of the Nicasil bores. When my engineer tried to bore out the barrels to insert iron liners, all his best cutting gear was wrecked.

 

Ahhh I was working with Guzzi in 1978..with the endurance racing team..... That wear at the top of the nigasil (guzzi patent) bore was normal only after 100,000kms + with paper filters or 5000kms running with K&N filters or similar, The bottom end would last with a well maintained motor over 250,000kms ( UNLESS you had the 850T that had NO filteration) where 5000kms would see you with a worn out crank! The crud would fill the cavity in the crank big end journal and then spill into the big end bearings, goodbye crank.....

 

 

[Old Koreelah]

Ahhh I was working with Guzzi in 1978..with the endurance racing team..... That wear at the top of the nigasil (guzzi patent) bore was normal only after 100,000kms + with paper filters or 5000kms running with K&N filters or similar, The bottom end would last with a well maintained motor over 250,000kms ( UNLESS you had the 850T that had NO filteration) where 5000kms would see you with a worn out crank! The crud would fill the cavity in the crank big end journal and then spill into the big end bearings, goodbye crank.....

Tell us more! I did a bit of pitwork for an endurance race last Sunday in Darwin, but those bikes were only doing 20min sprints before swapping transponders. Nothing like the endurance races run in Europe.

 

I had no idea Guzzi engines would last that long, given my experience. My V65 Lario is currently in hospital and I look forward to riding a proper bike again! Hopefully I'll get many years out of it.

 

 

[jetboy]

I was expecting to see some sort of announcement by now, maybe the testing hasnt gone well, looks like roller camfollowers are the answer for 2013

 

www.facebook.com/JabiruAircraft

 

 

[dazza 38]

Lets hope they have done a better job with this design than they have with their previous designs.

 

 

[eightyknots]

The main question will always be: how many GENUINE hours before the major overhaul is required?

 

 

[facthunter]

80K I think I know what you are driving at. This response is not directed at you.

 

TBO is an hours figure. Does not mean that no work be done. You monitor compressions not to note them but to do something about them if they do not meet specs. A full engine life (TBO) means a major rebuild is required, at that point regardless. Are some expecting that these engines will go the full time without a top for instance? Few engines will achieve that, and an engine in a plane flown with compressions low will not keep going for very long.

 

I wouldn't run a Jab over about 300 hours without seriously considering a TOP. ( heads off) inspection. A worn valve guide will subject you to the possibility of a head broken off the valve. Not an uncommon occurrence, and you will certainly know about it. You inspect your plane, change the brake pads, discs and tyres. Your engine is not a fit and forget item, just because it is a bit more mysterious. Visit the Jabba site. It's not high tech but it is relevent. Nev

 

 

[dazza 38]

I reckon alot of owners would be really jacked off if they had to remove a cylinder off a Rotax 912 at 300 hours. Actually they would be really jacked off it they had to remove a cylinder before 2000 hours.

 

 

[facthunter]

Maybe they would, but the parts are about 4 to 5 times as expensive and the rotax has starter (rectified later,if you did it) exhaust cracking and inlet rubber problems as well as a requirement for the reduction clutch to be inspected/serviced at about 400 hours. It also has the added complexity of being water cooled (in part). with hoses everywhere for oil and coolant. There is a lot of difference in the design philosophy of both engines. the Jab engine had to be made to replace an engine that was no longer available and was to be simple aircooled and cheap.

 

Different strokes for different folks. Neither engine is perfect. Can we be constructive about all this? Most car engine adaptions are far more unreliable and two strokes also. If you don't like the engine don't use it. I am not a basher or a promoter. If some pilot asked my opinion I would discuss the pro's and con's of both and let the person then make a decision.

 

If we had a bit more weight allowance we would have a bigger choice outside of the two that have been it for a long time now.. For reliability the Lycoming o-233 would be the best choice, but Wide and a bit heavier and pricier . Nev

 

 

[Old Koreelah]

I sure don't want to stir up any Jab bashing. I'm quite happy with my Jab 2.2 engine, which is lighter and more powerful than the VW donk it replaced.

 

A few years ago I had a long conversation with the factory about the possibility of a compression reduction (I don't need 85hp) to improve reliability and perhaps allow it to run on lower- octane fuel.

 

There are several engines in the 100+hp range but few choices below 80hp.

 

They were not supportive of these modifications; perhaps reducing output would have no effect on reliability.

 

 

[Sapphire]

Just keep flying the Jabiru and you will get an automatic reduction in compression, without trying.

 

 

[facthunter]

They retarded the timing instead which I reckon will lose power and make it run hotter. I think they did lower the compression by packers as well and the later cylinders are a bit longer. Clearly they think detonation is lurking. I agree so watch you temps and fuel used and it's age. Nev

 

 

[alf jessup]

Just keep flying the Jabiru and you will get an automatic reduction in compression, without trying.

Also the added bonus of a reduction in care factor from the company, if you don't buy it someone else will is the motto.

 

Fantastic airframe shame about the thing that spins the spinny thing.

 

Alf