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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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Re: Generation 4 Engine

Postby skypics234 » Thu Aug 08, 2019 3:37 pm

This is my 3rd Jab 2200. It is a Gen 4 2200.

I had to do quite a bit of modification to the air duct to fit under my low top cowl on my Avid MK 4.

I had some CHT temp issues with my front cylinders which were caused by my not installing the air dams correctly. The dams must be flush against the fins or else the airflow will dip under the cylinder instead of over it.

Here is what I have noticed on this engine (25 hours) as opposed to the Gen 2 engines.

1) This engine needs no oil between oil changes.

2) It starts instantly without ever using the choke. I believe this engine may be able to be hand propped. I will check it out.

3) It can idle smoothly as low as 500 RPM.

4) Oil stays cleaner much longer

5) This engine leans out much quicker when I turn the Hackman-type leaning knob.

6) This engine claims 80 HP as opposed to the earlier ones that claimed 85 HP.

7) I could not find a complete installation manual. When searching for it all I got was how to install the cooling duct.

8) The top two engine mounts were moved up 15 mm which necessitated buying a new $850 mount. Fortunately, I sold my engine and mount to recover some of the expense.

9) The engine seems to be much smoother

10) The CHT sensors are under a small screw that goes into the head between the plugs. I may change this setup to that way I measured the CHTs on my older engine. Namely, down deep in the hole between the plugs. I know from experience I will see higher temps, but I need to know how much higher.

11) The front two CHTs run higher than the rear two. The front two run around 300 F while the rear two run around 280 F in cruise at 85F OAT.

12) As on my older 2200s, I have found that here in SoCal replacing the 245 main jet with a 240 main works much better, especially when departing high elevation fields. On takeoff from high-density fields, I find that leaning out on climb out gives an additional 150 to 200 RPM while keeping the EGTs and CHTs in spec.

13) I do not have carb heat ability on this engine nor did I have it on all the others. I have a temp sensor mounted on the side of the carb body and have found while flying in snow and rain with OATs as low as 30 F the carb stays warm through conduction and convection from the engine.

In summary: I believe the weakest point on the older engines was the top end. Now with oil feed up the pushrods and into the rockers and valve stems I shouldn't have to reline the valve guides as I had to do on the older engines. The roller cam follower help in the smoothness. The much larger fins on the head and cylinders help dissipate the heat. The cast aluminum head/jugs combination allow closer tolerances to reduce oil usage.

I have sent my 1st oil change sample to Blackstone Labs for analysis just to get a baseline.

Finally: Jabiru says to use full mineral oil for break-in, but I have found that Phillips XC 20-50 can also be used for break-in and that is what I did.

I will report and new findings as I build more hours.

John M
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Re: Generation 4 Engine

Postby skypics234 » Sat Aug 10, 2019 11:23 pm

As I promised, here is a follow up on the Gen 4 engine.

It now has 28 hours and today I found a crack in the starter housing at the rear position.

I have posted a photo under the title Starter Motor Crack.

Will see what it takes to get a replacement from Jabiru Tennessee.

This should be a good test of customer support.

John M
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Re: Generation 4 Engine

Postby PKnight » Sun Aug 11, 2019 6:27 pm

I attach a copy of the 25hr oil analysis for information/comparison. Hope I have done it correctly.
My 3300 engine was a straight replacement on the engine mount (Jabiru standard fitting)
Attachments
PKNIGHT-33A2862-Friday, August 2, 2019.pdf
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Re: Generation 4 Engine

Postby skypics234 » Sun Aug 18, 2019 2:49 pm

RE: Gen 4 2200 cracked Bendix housing.

I received a replacement for the cast aluminum Bendix housing. The replacement is the billet style used on earlier generation engines.

This replacement actually looks better and I believe it can take the forces from the Bendix operation much better than the cast part.

Those with the new Gen 4 engines should inspect this part closely in the early hours of engine time. Maybe my issue was an aberration.

John M
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Re: Generation 4 Engine #2 EGT much higher than others

Postby skypics234 » Tue Sep 17, 2019 12:51 am

Hey guys;
Loving the Gen 4, but need your help on ain issue I am having. I am using only avgas on this engine. This concerns EGTs. I am not normally all concerned with the EGTs as long as the CHTs are well within spec. The CHTs run around 300 F.

Here is what concerns me. On full power climb out from my 533 MSL  field, all EGTs are in the low 1200s and only 20 degrees separate the highest from the lowest. These close readings are not that common. However, when I pull back tp cruise at 2850-2900 RPM the #2 EGT climbs way above the other three. It runs in the low 1300 F while the others run in the mid-1200s. Here's what I've checked:

There is no intake leak on that cylinder.
I have switched the thermocouples.

Still reads higher than the rest.

I have a leaning device (Hackman) in the engine as I used on the older engine. If I try to lean  #2 goes way over max very quickly. Compression is good a borescope shows normal exhaust valve condition after 50 hours.

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