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Generation 4 Engine

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Generation 4 Engine

Postby PKnight » Sun Jan 06, 2019 9:51 pm

Has anyone got a Generation 4 engine yet? If so any early views on it?
Peter
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Re: Generation 4 Engine

Postby bdirdal » Fri Jan 25, 2019 9:27 am

I have 2200 Gen 4 with 23 hour on the meter. Easy starting power-full engine.


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Re: Generation 4 Engine

Postby PKnight » Sat May 18, 2019 9:09 pm

I can now answer my own question as I have had a generation 4 engine fitted to G-PHYZ. It is engine number 3300. 2862

It is smooth and free of any significant vibration, but it is a (very) new engine with only 7 hours on the clock.

My comments are as follows:-
CHT's are well within the allowed range. With an OAT of 15 Deg C I was getting all CHT's in the Cruise as between 125 - 135 deg C On full power climb out the maximum was about 145 deg C.

The EGT spread is acceptable and seems to be comfortable at the lower end of the allowed range with readings from 615 deg C (min) to 645 deg C (max). I am not convinced that you can read much into these EGT's as very small variations in probe positions can lead to quite significant changes in the average temperature of the EGT probe. Incidentally the exhaust down pipes from the cylinders have been pre-drilled to take the EGT probes. The engine comes with these holes filled with a small blocking rivet that has to be removed but the process seems more convenient than drilling the SS steel of the downpipes. (nice touch).

On some 3300 Generation 4 engines there is the suggestion that the oil filter adapter plate has an off-set on it so that the filter can clear the cooling fins of Cylinder no 2. That is not the case with mine which has a cast bottom end. The oil filter fits on as normal with sufficient clearances.

The flywheel bolts are Norloc washers and can be easily seen without removing any bits. I think the actual flywheel is lighter so it may be that this fixing method removes the risk of the flywheel bolts breaking. They are certainly much easier to inspect.

Another small change is that the dip-stick has three holes drilled in it as Min/Max/ and mean oil level. It is easy to see and also easy to remove the dipstick when hot. (that used to be impossible on my old engine as the stick just expanded to the point where it was almost immovable)

The engine has new cylinders and these are effectively permanently screwed into the cylinder heads so there is no head tightening to do as was the case with the previous configuration. As with Generation 3 engines the pistons have valve recesses in them to avoid a problem with a sticky valve, double rocker springs and roller cam followers on the hydraulic tappets. As the cylinder heads are effectively permanently attached to the cylinders this is not an engine that you can tinker with. I think Jabiru have decided that the less maintenance is left to the owners that more likely it is that the engines will last without any excitement. That's fine with me but others may like to mess with the oily bits for their own satisfaction.

Now for a boring comment. If you look at the maintenance and the overhaul manuals for this engine they are comprehensive and well written. It is a professional job. The overhaul manual details good engineering practice and clear instructions that have not always been a feature of past publications by Jabiru!¬ 9 out of 10 for this (in a world where no one gets 10 out of 10).

This engine seems to address the concerns that have arisen with earlier types and so far they have been in production for 2 years and there have been no SB's or SL's that I am aware of so it is looking good. Only grumble is that it is still difficult to adjust the tacho pickup so that it works with the very small clearance 0.4mm., But once set it is ok. Oil use is negligible but too early days to sign this aspect off as a success.

From placing the order (with Skycraft) to delivery and clearing customs was about 6 -8 weeks which is acceptable.

My overall conclusion is that the generation 4 engine is a significant improvement over its predecessors but is designed to reduce the opportunity for (creative) owner tinkering. I fully accept that it is early days and I am a sceptical pilot always expecting something to go wrong. If it does I will let you know but I thought these comments might help those who are thinking about the differences that the Generation 4 engine offers to Jabiru (and other ) flights.
Happy to answer any questions if I can.
Peter
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Re: Generation 4 Engine

Postby diablo » Sat May 18, 2019 9:54 pm

Nice write up ... ;)

Can we have some pics of your installation please ?

thx
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Re: Generation 4 Engine

Postby PKnight » Sun May 19, 2019 8:32 am

Picture of Flywheel bolts. Easy to inspect without obstructions.

The Attachment of the exhaust and inlet pipes has changed. They are now secured by a clamp that holds both pipes for each cylinder. The clamp has a single (large) bolt retained with Norloc washer between the pushrod tubes. It is technically a single point of potential failure but much easier to check and should not be under significant load.

I will try for better pictures next time I am in hanger
Attachments
IMG_4194.JPG
Inlet and exhaust tube retainers
IMG_4186.JPG
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