Latest Jabiru 2200 - reliability

[Old Koreelah]

9 minutes ago, facthunter said:

I don't know what rotated means in your context. Do you mean swapped or made to rotate (which can be done with special washers" Hydraulic lifters often use stronger valve springs also increasing loads.  Nev

Sorry Nev, not swapping. I mean turning each valve stem to make sure the lifter isn’t jammed solid.

[facthunter]

I presume you mean run out of adjustment? You have to bleed the oil out of it to check that. My choice would be roller followers with manual adjustment.  Nev

[RFguy]

Balazs
"It this could cause the seals to deform and be ejected, which I also wanted to avoid."
No, this will not occur . too much oil and it will simply be ejected out the dipstick crankcase breather. It is suspected (no proof) that high oil levels  can contribute to oil foaming and loss of oil flow and higher temps, but you dont have this problem.

 

100-115kmh.  (57kts) 

This is  too slow.  The manual specifies a minimum of 2.4 inches of water (600 Pascals) at 25 deg C  across the inlet plenum and the cowling inside . 

JEM3302 .  see section 11.9.    2.4" of water across the plenum requires about  3.4" of water  ram air pressure - depending on cowling exit size. 

so the minimum airspeed that this can be acheived is 65 knots (120 km/h)  and that's at 25 deg C

 

Use of a negative p[ressure cowl lip to increase the pressure differential is likely required.  It really is just too slow for a Jabiru eninge with standard plenums

 

I highly recommend you read chapter 11 " cooling system  " of the JEM3302 manual (engine installation)  !

https://jabiru.net.au/wp-content/uploads/2020/04/JEM3302-9-_Inst-03_04-20.pdf

 

 

[Old Koreelah]

1 hour ago, facthunter said:

I presume you mean run out of adjustment? You have to bleed the oil out of it to check that.

 

I guess that’s what they meant. 

1 hour ago, facthunter said:

My choice would be roller followers with manual adjustment.  Nev

My preference also, but I have to soldier on with what I have. Converting it to manual adjusters is not simple and I doubt the parts are still available.

[Balázs Dianovics]

Thanks to everyone for the replies so far. You gave me great ideas and I am optimistic! I'm done with a small modification, but I've been sick, so unfortunately I haven't been able to reassemble and test it, but maybe soon. I still have a lot of faith in increasing the speed, and I try to block the air leaks before the first test.
My question is, what kind of material should I use there, which can be shaped well and withstands the necessary heat? A rubber sheet would be good, for example, or epoxy resin painted and glued on fiberglass, or what would anyone recommend for sealing?
In the attached image, I have marked in magenta what I want to block from the outflow path. I also found two rather large holes on the inner side of both flow pipes (also colored in the picture) that I would block. Maybe it would be used to connect the ignition cable, but I think I won't have a problem with it if I don't have a cable there and seal it.

[Old Koreelah]

Good morning Balázs. 

Your installation looks neat, but those big leaks need to be plugged.

I’d use Vinyl Ester resin if available, because it is more tolerant of heat than epoxy. To plug small gaps temporarily I just scrumple up some aluminium foil and jam in. Silicon rubber sealant might be useful around your ignition cables.
 

Those two big holes cut in your ram air ducts by the Jabiru factory are meant to provide cooling air to the crankcase and the rest of the engine, but they sure reduce the air pressure where it’s needed most: through the heads.
I closed mine off long ago. Likewise for the small ducts that direct cooling air towards the ignition coils. I plugged them. Now my coils are cooled by a pair of 25mm scat hoses that run directly from the front of the cowl. That cooling air probably helps cool the rest of the engine.

You could make a small fitting out of sheet aluminium to plug the air gap between the two tappet covers. It could be held in place by the two nearest cap screws.

 

From your pictures, it’s not clear if air passing through your oil cooler exits separately, under the cowl. It’s prefered to do this, so there’s lower air pressure under the engine, which help suck more cooling air down through the fins.

[Markdun]

On 23/7/2023 at 2:01 PM, Old Koreelah said:

 

I guess that’s what they meant. 

My preference also, but I have to soldier on with what I have. Converting it to manual adjusters is not simple and I doubt the parts are still available.

The hydraulic valve lifters bottoming out (out of adjustment) and holding a valve slightly open is a not uncommon problem with the 3300 with the older longer pushrods (Gen3) and which have suffered some head recession.  What I was advised by Jabiru to do was to check at each oil change whether the rockers could be moved by hand fwd and bkwd (sliding) along the rocker shaft a fraction of a mm at TDC power stroke. No need to rotate valves. If the rocker can’t slide along the rocker shaft a smidgen (it will also swipe the top of the valve stem), then you need to investigate further.

 

Also when assembling the engine extract the oil from the lifters so they are all bleed down and measure the tappet clearance when assembled. There’s only 3mm working movement of the lifters so to be in the middle of the range you should have about half of that (it’s not exactly half because the rocker aren’t 1:1). I’ve found in most engines you can swap around the pushrods as they are not of identical lengths to get a pretty consistent set up. In a couple of engines I’ve found a couple of pushrods significantly different in length…obviously mix ups with early and later versions.  
 

I think someone (Jabiru) should produce a colour card for the rocker boxes colour, like spark plug manufacturers. I’ve come across some totally black ones: real doosies.  I too, expect shiny ‘silver’ aluminium and have my CHT panic alarm set a bit higher at 155C.

 

 Cheers, Mark

[Old Koreelah]

I just found a resource that might be helpful when checking oil level: