Engine Cooling for the Jabiru engine

The Jabiru Engine which is used in many other aircraft.

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lessersg
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Re: Engine Cooling for the Jabiru engine

Unread post by lessersg » Wed Feb 21, 2018 5:38 pm

So guys seems the plenum works, this is a full power climb out AOT 30 deg. Dont worry about Fuel flow, oil pressure etc, glitch with the IEFIS again.

Still room for improvement, front of the plenum needs to be blocked but that's about all. I'm sure we can still drop these temps further
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Re: Engine Cooling for the Jabiru engine

Unread post by Steve » Wed Feb 21, 2018 6:26 pm

So any indication when the units will be available as a kit to fit and what the price will be?
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Re: Engine Cooling for the Jabiru engine

Unread post by lessersg » Thu Feb 22, 2018 8:12 am

Steve wrote:So any indication when the units will be available as a kit to fit and what the price will be?
Steve this was the prototype to prove concept. Now that we know it works we need to make a few changes.

1. Front on plenum needs to be changed to stop bleed air moving forward.
2. Needs to be designed so bottom ducts can easly be installed. Right now as it stands requires a bit of glass work. Not ideal, but I have a few ideas

So.. Have one more mold to make from that the final plug will be made using tooling resin. I have no idea what the cost will be all depends on material cost per plenum, have not even thought of that yet. I have to make sure this works 100% first must be 100% plug and play lol dont want our jabi owners to still mess around trying to make it work. So Id say about 3-4 months before Im ready to say come and get them lol...
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Re: Engine Cooling for the Jabiru engine

Unread post by Marius Schrenk » Thu Feb 22, 2018 6:22 pm

Thank you very much for the R&D. =D> =D>
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Re: Engine Cooling for the Jabiru engine

Unread post by Patrick H » Thu Feb 22, 2018 9:42 pm

Very big well done on sorting the JAB cooling problem out on gen 3 and earlier models. I really think you onto a winner here. =D>
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Re: Engine Cooling for the Jabiru engine

Unread post by lessersg » Fri Feb 23, 2018 8:52 am

Patrick H wrote:Very big well done on sorting the JAB cooling problem out on gen 3 and earlier models. I really think you onto a winner here. =D>
I really hope so, think by cooling the whole engine and not just the heads is also helping plenty. Our oil temps dropped by 10 c as well in the cruise.
Its important to remember that the results are only as good as the installation, meaning that leaks have to be stopped. Same with the current ram air ducts. After sealing ours we managed to drop the temps substantially.
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Re: Engine Cooling for the Jabiru engine

Unread post by J430 » Sat Feb 24, 2018 2:15 am

I'm surprised to hear your oil temp dropped... are you running the big gold square oil cooler? I find that it works way too well, never getting anywhere near above the recommended temp, which is why I fitted the TOCA oil thermostat.
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Re: Engine Cooling for the Jabiru engine

Unread post by lessersg » Sat Feb 24, 2018 6:39 am

Nope standard oil cooler.....
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Re: Engine Cooling for the Jabiru engine

Unread post by lessersg » Thu Apr 19, 2018 11:26 am

Made a small modification to the front of the plenum, think I have it done now. Will see if I can get the new mold done in the next few weeks or so just very busy right now.
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Re: Engine Cooling for the Jabiru engine

Unread post by Flooi » Thu Apr 19, 2018 12:25 pm

Now another silly question.... why are the users.... the customers.... working so hard to
sort out a problem that is decades old? Why has the manufacturer not done this ages ago?
Simply cannot figure this out..... 8-[
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Re: Engine Cooling for the Jabiru engine

Unread post by lessersg » Thu Apr 19, 2018 1:38 pm

Flooi wrote:Now another silly question.... why are the users.... the customers.... working so hard to
sort out a problem that is decades old? Why has the manufacturer not done this ages ago?
Simply cannot figure this out..... 8-[

Maybe because they haven't realized there is a problem. Maybe I'm the only one having this problem because I have Fuel Injection rather than the Antiquated Bing fiasco....who knows. ANYWAY..my problem is sorted.
Might change a few things later if I have the time. Thinking off maybe having the top of the plenum removable, easier for maintenance as its a bit of a bitch removing the full plenum.
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Re: Engine Cooling for the Jabiru engine

Unread post by lessersg » Thu Apr 19, 2018 1:52 pm

I have a question for the boffins.

Truth be told please------

Speaking to an instrument technician a few weeks ago, he indicated that it is the norm for the RDAC or any other make to measure the ambient temperature inside the cowl and add this to the CHT and EGT temp reading. Is anyone familiar with this equipment or can confirm this statement.

I do know that this happens with the MGL RDAC unless I misunderstood I did ask three times for an explanation ......
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Re: Engine Cooling for the Jabiru engine

Unread post by GPsucks » Thu Apr 19, 2018 2:58 pm

lessersg wrote:I have a question for the boffins.

Truth be told please------

Speaking to an instrument technician a few weeks ago, he indicated that it is the norm for the RDAC or any other make to measure the ambient temperature inside the cowl and add this to the CHT and EGT temp reading. Is anyone familiar with this equipment or can confirm this statement.

I do know that this happens with the MGL RDAC unless I misunderstood I did ask three times for an explanation ......
Sounds like BS to me. Park your aerie in the sun and check CHT and EGT readings, the EFIS should indicate OAT or a bit more on both, so 'cowl' temperature is already displayed. EGT, CHT will indicate respective temperature just as a tyre pressure gauge indicates pressure in the tyre which is gauge pressure because it measures 0 psi at 'rest' but the pressure on the gauge would be 14.7 PSI at sea level on a 'standard' day. (A bit less here in GP) In other words, a tyre pressure gauge indicates the difference between the pressure outside the tyre and the pressure within the tyre. The EGT CHT gauge would do the same IE measure the differential between cowl temp and EGT CHT, not add cowl temp to the value, rather subtract it.
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Re: Engine Cooling for the Jabiru engine

Unread post by heisan » Thu Apr 19, 2018 3:23 pm

lessersg wrote:I have a question for the boffins.

Truth be told please------

Speaking to an instrument technician a few weeks ago, he indicated that it is the norm for the RDAC or any other make to measure the ambient temperature inside the cowl and add this to the CHT and EGT temp reading. Is anyone familiar with this equipment or can confirm this statement.

I do know that this happens with the MGL RDAC unless I misunderstood I did ask three times for an explanation ......
A thermocouple (as used to measure CHT and EGT) measures the difference in temperature between the probe and the 'cold junction' (the point where the thermocouple wire connects to the display)*.

Old temperature gages just estimate environmental temp and display the result (so if the cold junction is 10 degrees hotter than normal, it will show 10 degrees *colder* than expected).

Modern EFIS systems though a re 'cold junction compensated' - there is a separate thermometer that measures that absolute temperature of the cold junction, adds the thermocouple relative temperature, and displays the real temperature (irrespective of environment temperature).

The MGL RDAC *is* cold junction compensated, so should be accurate in all conditions.

* NOTE: Some people extend thermocouple wires with copper wire. This moves the 'cold junction' to the join in the wire, and the resulting reading will be off by the difference between the temperature at the junction and the temperature at the instrument.
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Re: Engine Cooling for the Jabiru engine

Unread post by lessersg » Thu Apr 19, 2018 3:25 pm

GPsucks wrote:
lessersg wrote:I have a question for the boffins.

Truth be told please------

Speaking to an instrument technician a few weeks ago, he indicated that it is the norm for the RDAC or any other make to measure the ambient temperature inside the cowl and add this to the CHT and EGT temp reading. Is anyone familiar with this equipment or can confirm this statement.

I do know that this happens with the MGL RDAC unless I misunderstood I did ask three times for an explanation ......
Sounds like BS to me. Park your aerie in the sun and check CHT and EGT readings, the EFIS should indicate OAT or a bit more on both, so 'cowl' temperature is already displayed. EGT, CHT will indicate respective temperature just as a tyre pressure gauge indicates pressure in the tyre which is gauge pressure because it measures 0 psi at 'rest' but the pressure on the gauge would be 14.7 PSI at sea level on a 'standard' day. (A bit less here in GP) In other words, a tyre pressure gauge indicates the difference between the pressure outside the tyre and the pressure within the tyre. The EGT CHT gauge would do the same IE measure the differential between cowl temp and EGT CHT, not add cowl temp to the value, rather subtract it.
So what you saying is my EFIS is displaying the total value Cowl temp plus EGT and CHT? Why would they do this? I want to see what is at the probe. Suppose the probe will pick up ambient ( in the cowl ) as well. Its called cold junction compensation so I have been told. Was told if the probe is disconnected from the RDAC you would see terminal temperature. So that valve would be subtracted from the value seen on the IEFIS....Well that sucks .....Why is this done.

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