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jetjr

Jabiru engine cooling

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We like the MGL Extreme EMS for legibility for its size (we're actually building a brand new panel for the ST that incorporates it and an iPad as standard, but that's some way off, though the trial mould looks encouraging ). The MGL Extreme handbook is worth downloading and having a read through, if only to give you a bit of a 'baseline' for capability; it pretty much ticked all our boxes for the combination of size, price, capability and readability. I'd not be surprised in the Dynon doesn't have even more capability. One thing we really like about the Extreme is the external connection of a 'something's happening' light we're going to sit between the ASI and Altimeter right at the top of the panel so it's in the line of peripheral vision (of my damn bifocals..) in normal flight - and since it's programmable for every condition, it's just a 'look at the damn Extreme and see what's happening' instant reminder.

 

 

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Yeah, my Dynon has LOUD alarm through headsets, plus whole bottom of screen goes red with alarm noted, goes off at shutdown and still frightens me. Without engine noise its pretty loud.

 

There is a skill programming alarms, too low they go off regulalry, too high you never know whats happening until too late. Also some things go into alarm on landing and taxi like oil pressure.

 

It has "yellow" limits for CHT and EGT (everything actualy), certainly catches your eye but no alarm

 

 

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Cooperplace anodising might be better but I've never seen it used. Every engine I have seen (bar model ones and that are usually colours for appearance) uses paint. I did say Thin coat. There have been tests done and even the surface finish matters. (Polished is bad). Whilst it as a radiation THING rather than conductive, the heat would be radiating out into a stream of air, so I suggest the effect would be significant if not earth shattering. A nice shiny billet machined motor might appeal to some but engines are rarely used in that condition. I'd like some airflow figures when the leading edge of the fins on the heads is a little more shaped aerodynamically too. Take a while to do it by hand but I would do it to one if I had it. Nev

 

 

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Getting a 4 in one guage that fits my existing hole, is proving a problem........ 2 in one, easy,

 

( Rotax 4 banger )

 

So 2 censors is better than just the one I spose , perhaps I site one on the LHR cyl, other RHF cyl. .??

 

Getting back to my current position, installing that "lip" has noticeably dropped the temp on my LHR cyl, surely then, one could assume that this has also had a positive effect on the other 3 cyls......surely.

 

Any.........drop in the engine bay must be benificial overall.

 

 

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You can make what are logical assumptions, but they are still assumptions. Originally I would have thought having 1 sensor per cylinder overkill. Perhaps move the sensor around and try to find the hottest cylinder, and in so doing have an idea of the difference. Nev

 

 

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have a look at these cheap as and they are a good unit.

 

http://www.mglavionics.com/html/velocity_singles.html

 

scroll down to this unit, TC-2 4-channel Thermocouple Monitor

 

or try this one; TC-3 12-channel Thermocouple Monitor

 

Either for about $350 and the AU dealer is a very helpful guy, if there is any trouble you ring him and he talks you through everything, he even sent a unit up on the bench for me when i was having trouble.

 

I just found the local guys contact details if anyone wants them;

 

[email protected]

 

 

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Once the installation is working OK it should stay that way unless it involves seals and baffles that have failed or deteriorated. These aspects should be easy to spot on normal inspections. You don't want your cockpit panel to look like an early Jumbojet, because you are supposed to be looking outside a lot. Nev

 

 

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Getting a 4 in one guage that fits my existing hole, is proving a problem........ 2 in one, easy,( Rotax 4 banger )

 

So 2 censors is better than just the one I spose , perhaps I site one on the LHR cyl, other RHF cyl. .??

 

Getting back to my current position, installing that "lip" has noticeably dropped the temp on my LHR cyl, surely then, one could assume that this has also had a positive effect on the other 3 cyls......surely.

 

Any.........drop in the engine bay must be benificial overall.

Keep single gauge fit 4position rotary switch to select all sensors indavidually

 

Mick w

 

 

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I'm using the MGL gauge (Brilliant).

 

Sourced the Thermo-couples from China through Ebay "Aerospace".

 

Special order with 12mm washers (Underplug), each with 2m of stainless sheathed wire probes, ended up around $4.00 ea so I got a few extra.

 

Did the boiling water test and each one was spot on.

 

Been in for around 3 years, never needed to use a spare yet.

 

But then I went to liquid cooled heads, so no overheating problems, just a fancy gauge to look at.

 

 

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Absolutely right - and very important. Jab. kicked a monumental own goal, I believe, by not mandating at least CHT reporting for ALL cylinders, on an engine that undeniably requires careful attention to operation. I'll bet London to a brick that there are a considerable number of owners who have been very careful, done all the right things as far as they could tell - and not been rewarded with the engine life they had every right to expect. And they have every right to be angry and feel that the engine has simply let them down, when better information about what was really happening could have made a vast difference to the life they got. Jabiru make strong recommendation about having probes on all cylinders for any non-factory installation, yet they skimped on the factory installs. They make a damn competitive airframe with most things costing way more to buy, yet they don't give it the chance to deliver its best by skimping on instrumentation.

The cost of three, or even five extra probes and a suitable instrument (e.g. the MGL Extreme EMS in a package deal with six CHT and 6 EGT probes), is about A$2k. That's a bit more than pocket change, for sure, but if you get just 400 extra hours to first overhaul as a result, it's paid for itself, what - about 4 times?

Oscar, how the hell is spending 2 grand on instrumentation going to save you an overhaul - if it's running hot, it's running hot, and you have still got to do something about it. In 2000 hours I have been through 4 engines and at least the same amount of top ends.

 

 

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Coz if a cylinder is running hot and you know about it you can fix it. If you dont know then you only have a pretty good chance of engine problems

 

Just watching one or two rear cylinders is a waste of time.

 

Problem is the engines dont run uniformly hot, can have rear one or two OK, and another VERY hot, without full instruments you wont even know its happening.

 

8 full rebuilds in 2000hrs would tell you something is wrong

 

Yours is maybe a good example of why you should have full instruments.

 

Additionally when flying and something goes wrong, you can tell earlier and do something about it rather than keep flying and do serious damage.

 

 

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interesting document dlegg, thanks.

 

Much of the head cooling problems are reduced with fine finned heads, I see they are battling with older versions.

 

J400 cowl inlet and oil cooler were under done and new J430 setup can work well but still needs adjustment.

 

Of much interest is the comments on pressurizing Bing and blocking of NACA inlet with tape and cutting hole.

 

My experience backs this and running with carb heat on, or even part way on, sees much more even EGT. Think some test bay work underway is also supporting that problem is developed upstream of carb.

 

I was going to try operating with "protected" inlet, (non heated air from inside cowl) but this is easier and could do similar.

 

 

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I found I had to disconnect naca duct on cowl to mixer box. With extra pressure the engine would run very rough at full revs. Runs fine now. Put a filter on naca to slow flow into cowl, but still plenty of fresh air to mixer box. Carb inlet temps also higher. Egt's much more even as a result. Full power climbs and middle cyls always run coolest egt.

 

 

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