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scsirob

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    WANTED : Jabiru Tachometer with inductive sender

    in Instruments, Radios and Electronics

    Posted

    On 20/02/2022 at 7:18 AM, Bruce Tuncks said:

    The Jabiru sender is interesting in that it is screwed directly onto the engine block against the sender instructions.

    So it fails from vibrations...

     

     

    Actually, the oil sender fails from rapid fluctuations in the oil pressure. Several have researched this and it comes from the pressure regulator valve hammering open-close-open-close. The oil pressure sender is just a wire-wound potentiometer resistor with a mechanical wiper, and it dances with the rapid pressure pulses. This quickly wears out the wire and that makes the sensor fail.

    • Like 1
    • Informative 2

    Oil Cooler Orientation

    in Engines and Props

    Posted

    7 minutes ago, skippydiesel said:

    Wow! thatch one very nice looking set up. What brand/size cooler is that?

    Thanks! I built a plenum around the sump so the air passes along the sump and through the oil cooler, then down and out through the bottom of the cowl. That way it doesn't upset the low pressure needed for head cooling too much. Got two 3-into-1 CAMit mufflers, so there's ample space.

     

    The cooler is a universal type, I got it from a local VW hotrod shop: https://www.hotrod.nl/shop/contents/nl/p3271_Oliekoeler_element_48_rijen_____280_x_190_x_40_mm_.html

    I've seen similar ones in webshops around the world. In retrospect I should have gotten one size smaller, perhaps I'll swap it out later this year.

    • Like 1

    Camit 3300 reliability?

    in Engines and Props

    Posted

    6 minutes ago, rnothard said:

    Zhou look zein om u te ontmoeten. Win vaaren naar Europa in demo RE van Australia.

    Sounds like a great adventure! Just let me know when (if?) you are visiting The Netherlands, would be great to meet! Hele fijne reis en misschien tot ziens 😉

    Camit 3300 reliability?

    in Engines and Props

    Posted

    That would be 33SLRE-64 then, the '5' is actually an 'S'. Never found a decoder ring for the letters, but SL probably means 'Solid Lifter' (which they all are).

    The serial number is past the early piston spring issues and before Camit had to scrape the bottom of the barrel for parts. Others may know more about the piston issues, but I'd take that engine any day.

    • Like 1

    Camit 3300 reliability?

    in Engines and Props

    Posted

    Do you know the serial number? I have 0112L which was produced a month or two, maybe three before the demise of Camit. It runs pretty sweet, no signs of trouble after ~250hrs in my Rans S-6S. When mine was built, Camit was already struggling. The highest serial number I have heard of was from someone in South America, around 0121 or so.

     

    Early Camit engines were said to have been fitted with wrong material piston rings and/or fragile pistons, but that would have shown after less than 200 hrs. Ask for maintenance logs, ask if there was any major work done, ask why the owner wants to sell after just 200 hrs.

    airworthiness suggestion AS/JAB/1

    in Engines and Props

    Posted

    On 14/06/2021 at 6:01 AM, facthunter said:

    A properly designed and installed "O" ring should not require sealant.

    Jabiru seems to not know that. They have used sealant on the rubber rings of the intake manifold from day one. They also use sealant on the oil pump that also has O rings installed, both on the back plate as well as the housing. On the Gen-4 engine they have changed the back plate design to include a second O ring (found in the CAMit engine), and they removed the sealant requirement there.

    Running a Jabiru engine on Mogas?

    in Jabiru

    Posted

    This is my local experience in The Netherlands. I ran my previous Jabiru 3300 exclusively on Mogas (Euro-95) without ill effects. My current CAMit 3300 has 150 hours on it with Mogas as well. Last year after local authorities upped the Euro-95 ethanol content to 10% I started to notice rough running in some situations. I moved to Euro-98 BP Ultrium. This is labelled E5 which means up to 5% ethanol, but we have written confirmation that BP Ultrium for now has zero ethanol in it. Mogas keeps the engine relatively clean.

    • Like 2

    Carby heater on a Rotax 912

    in Engines and Props

    Posted

    I wonder if it is trying to heat the carb body close to the venturi and not the air passing through.

    It's attached to the input side of the carb. The largest risk of ice forming is at the opposite side, at the butterfly. Especially with low power settings and the butterfly almost closed.

     

    The engine is a huge air pump. At 4600 rpm and 1200-1350cc displacement, you are looking at about 40 liter of air per second passing through that venturi. That's a lot of cooling capacity. Having 50W or 100W of electric heater on the outside of the carb body won't make a dent in the temperature of the mixture passing the butterfly.

     

     

    Carby heater on a Rotax 912

    in Engines and Props

    Posted

    From the pictures it looks like it is on the input side of the carby. That makes no sense. No amount of available electric power on that side will significantly raise the input air temperature enough to avoid carb ice.

     

    There's other electric carb heaters producing about 50W that attach to the butterfly side where it may help a bit, and they are hardly effective. I'd opt to remove this pre-heater contraption and find a way to install proper hot air carb heat from near the exhaust pipes

     

     

    • Agree 2

    CAA Exemption for 25 Khz radios. . .

    in UK/Europe General Discussion

    Posted

    Our airfield frequency changed from 129.825 to 129.830 last month, ( in case you're flying nearby ). . .

    Nope. The frequency didn't change. Only the identifier did. In 8.33 world they don't speak of frequencies, they speak of channels. And Channel 129.830 happens to transmit and receive on 129.825MHz.

     

    The only thing that changed is the bandwidth. If you keep down your voice, your 25kHz radio will transmit nicely within the 8.33kHz wide channel. And you'll be able to hear those 8.33kHz stations just fine, but you may have to turn up the volume a it.

     

    The only problem is that your 25kHz radio may splatter over the adjacent 8.33 channels.

     

     

    How to improve the reliability of the 6 Cylinder Jab

    in Jabiru

    Posted

    Jaba

    There are no droplets of fuel if that was the case the carby is not doing its job. Also it’s not possible one side of 

     

    the engine to run lean and other run rich.

    You are kidding, right?? *THE* documented way to even out left-to-right EGT's in Jabs is to tilt the carby slightly to the left or right. The only reason this has any effect is because the poorly mixed stream hits the manifold divider, guiding more or less fuel to the left or right bank depending on offset of the carb atomizer and air stream. If the fuel was mixed properly, any tilt would have zero effect.

     

    I wish I could find the video again, but Pete Krotje, long-time USA dealer for Jabiru, had a transparant manifold made, to study what goes on. It shows solid fuel droplets coming from the carby. There are several documented mods for the carby to improve atomization, but distance from carb to manifold simply is too short for the fuel to atomize properly.

     

     

    • Agree 3

    How to improve the reliability of the 6 Cylinder Jab

    in Jabiru

    Posted

    Short of some major changes nothing much will change that. Stiffy was always reluctant to change to a more complex system for a lot of reasons. 

    The only real way to change things is to separate the carby from the plenum. This will allow the air+fuel droplets to change into a real mixture. Right now the fuel droplets simply don't have time to atomize and mix before getting to the plenum. This means puddles of fuel in unpredictable places and uneven mixture that changes seemingly random.

     

    Limbach used to have a setup where the carby was on top of the engine, and the fuel/air mixture had to travel half a meter through an aluminum tube to get to the plenum below the engine. This worked a lot better.

     

     

    • Agree 1

    Iridium plugs

    in Jabiru

    Posted

    With all the varying installations and different user techniques that the engine is exposed to it's completely unlikely that just ONE plug type will be suitable for all occasions.

    Plug temperatures have more to do with the ability to dissipate heat in balance with the amount generated by the engine. Heat Range : NGK Spark Plugs Australia | Iridium Spark Plugs | Glow Plugs | Oxygen Sensors | Ignition Leads | Ignition Coils

    Considering the strict ranges dictated by Jabiru for CHT and EGT, I would suggest that differences in installations are not much of a contributor. Jabiru users usually run their engines just below recommended maximums, or they struggle to keep the engine run cool enough and plug heat range is least of their worries. For EGT the user has no control over how the carb sets mixture unless you start fiddling with the needles and jets, or run a throttle body.

     

     

    Iridium plugs

    in Jabiru

    Posted

    ..Not having much choice of heat range of the plugs is a bit worrying also . It's never mentioned. How ridiculous to have not investigated it in the Jabiru fisaco

    I'm confused now. What fiasco? Are you saying that plug temperature is a factor? Where's the proof? It's not for a lack of available plugs, D7EA and D8EA are just as abundant as D9EA, but I have yet to see any evidence or even hints that this may be a good idea. You are not encouraging people to deviate from the manufacturers choise, are you??

     

     

    • Agree 1

    Iridium plugs

    in Jabiru

    Posted

    Your engines reliability is a much higher priority. A resistor MUST lower the AMPS. and it does affect the spark. It may jump the gap but it's much less intense. The plug points last longer because the spark energy is less. Nev

    Straight from the horse's mouth : PLUG STUDIO / NGK

     

    The resistor is not there to make the points last longer, it's there to stop RF from traveling back into the ignition wires and causing noise.

     

    AMPS are not a factor. The ignition system is a high VOLTAGE system (20kV+) with a limited amount of energy (<50 milliJoules) available. That means very low amps. Lets take 1mA as an example. At that current, the loss across a 5kOhm resistor would be 5V. Now how much impact would losing 5V out of 20.000V have? Even if you'd lose 50V (@10mA), or 500V (@100mA), the effect would be negligible.

     

    Here's an interesting article about ignition systems, voltages and energy: ignition comparison - EFII

     

     

    • Like 1

    Iridium plugs

    in Jabiru

    Posted

    NGK does not recommend using their product on aircraft engines at all. I can't find a link right now but recall seeing something along the lines of "Not for aircraft use" on the box that the NGK spark plugs ship in. The gap spec for the D9EA comes from Jabiru, we must take their word for it that that's a good starting point in their engines.

     

    As for gapping in common terms, NGK FAQ ( FAQ : NGK Spark Plugs Australia | Iridium Spark Plugs | Glow Plugs | Oxygen Sensors | Ignition Leads | Ignition Coils ) says the following:

     

    "What is the maximum I can open or close the gap?

     

    For nickel spark plugs the maximum is 0.1mm. We do not recommend adjusting the spark plug gap any further than this as the centre and ground electrodes won’t line up properly, hindering spark plug performance.

     

    For precious metal spark plugs, NGK Spark Plugs (Australia) do not recommend adjusting the gaps as the fine centre electrode is not designed to withstand mechanical force and can easily be damaged."

     

     

    Iridium plugs

    in Jabiru

    Posted

    The worst thing you can do to a high voltage system is open circuit it.. A shorted out circuit does no harm at all.

    Agree. The energy has to go somewhere. Without a spark plug to dissipate the energy, it will find some other path. That may well be inside the magneto, causing irreversible damage to internal insulation.

     

    If you recommend things relating to an aeroplane, you have an obligation to not publish anything that may be dangerous. Nev

    Can't see that I made any recommendations, other than not to fiddle with the Iridium spark plug gaps.

     

     

    Iridium plugs

    in Jabiru

    Posted

    The series resistor is fairly small (~5kOhm), and does not affect the ignition system by much to initiate a spark. The resistance of the wire insulation is orders of magnitude larger than the series resistor. When the high-voltage energy travels through the ignition wire, it sees no resistance. Even when it gets to the resistor, it passes right through without energy loss, as no current flows just yet. The voltage potential builds up, trying to find a way to ground.

     

    When the HV potential reaches the tip of the spark plug, the air gap between the tip and the ground pin breaks down and the spark starts. That's when current flows, and that's when there's an effect on energy. The spark will be slightly less energetic as less energy is available to 'feed' the spark and keep it going. But the effect is also that RF from the spark which tries to make it's way back to the ignition wire gets dampened by the series resistor. For RF, the ignition system has a low impedance so the impact of the series resistor is large.

     

    At altitude, thinner air will have an effect when your ignition wire insulation is in poor shape and a path through the insulation and thin air breaks down before the path through the spark plug does. This may happen sooner with a resistor spark plug, as the energy that is supposed to feed the initial spark at the plug now has to overcome the extra resistance and finds an easier path. When your ignition wire is in good condition, this is not going to happen.

     

    As for gapping the plugs, leave them as delivered. The spec from Jabiru is for regular plugs which have a much larger tip surface. The Iridium plug tips are much thinner, concentrating the HV energy onto a smaller surface. That makes it easier to bridge the gap at factory setting.

     

     

    • Like 1
    • Informative 1
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