Jabiru Phil Posted April 16, 2014 Posted April 16, 2014 How would a chamber from the carby channelled to feed EACH pot go? With say an adjustment mechanism to fine tune each cylinders requirements? Just thinking like.
facthunter Posted April 16, 2014 Posted April 16, 2014 They are still connected and full of combustible mixture. A plenum doesn't distribute mixture evenly ( Unless it is gas then it is less likely to separate, but still has to be mixed in the first place). Nev 1
JabSP6 Posted April 17, 2014 Posted April 17, 2014 Too all those thinking about upgrading to one of Ian's motors I would suggest you take the time to talk with Ian about all the changes he has made. He will be at natfly for those who can't make it Bundy to talk in person with Ian. Last weekend I did the 175 hr service on the engine. Unfortunately I have nothing out of the ordinary to report for you all. All the head bolt tensions were good. All the valve clearances were spot on. Everything is performing the way it should. We pulled both the plugs from each cylinder to look at the top of the pistons and check the sealing faces of the valves. Ian was there to look at this and was pleased at the results. Everything was looking nice and clean inside. The leak downs are all 76/80. Prop pull thrus are all very positive with engine both cold and hot. Nice positive kick back even when I land straight after every 2 hr flight. It is good to be able to just do the normal regular maintenance and not have to remove heads due to low leak downs. I am finally enjoying flying my plane with a lot more confidence in the motor and spending less time working on it which is great. Safe Flying Andrew 6 1 1
Oscar Posted April 17, 2014 Posted April 17, 2014 Andrew - great to have the continuing feedback. Do you have chts and egt's on all pots? - it'd be useful to hear what temps you are getting!
JabSP6 Posted April 17, 2014 Posted April 17, 2014 Yes I have an MGL mini Efis fitted. I have done extensive work modifying the air inlets and outlets on the engine cowls as well as the oil cooler ducting. The highest CHT's I have seen is in climb out during summer. 145 degrees. Normal cruise temp are between 110 in winter and 125 in summer. I have all 6 temps within about 10 degrees. The egt's still have about 40 degrees spread in cruise which I have not done too much about yet. In all I am very happy with Camit's engine and I am looking forward to doing many more hours flying without having any issues. I will keep everyone informed. Safe flying Andrew 1 3
biggles Posted April 17, 2014 Posted April 17, 2014 Too all those thinking about upgrading to one of Ian's motors I would suggest you take the time to talk with Ian about all the changes he has made. He will be at natfly for those who can't make it Bundy to talk in person with Ian.Last weekend I did the 175 hr service on the engine. Unfortunately I have nothing out of the ordinary to report for you all. All the head bolt tensions were good. All the valve clearances were spot on. Everything is performing the way it should. We pulled both the plugs from each cylinder to look at the top of the pistons and check the sealing faces of the valves. Ian was there to look at this and was pleased at the results. Everything was looking nice and clean inside. The leak downs are all 76/80. Prop pull thrus are all very positive with engine both cold and hot. Nice positive kick back even when I land straight after every 2 hr flight. It is good to be able to just do the normal regular maintenance and not have to remove heads due to low leak downs. I am finally enjoying flying my plane with a lot more confidence in the motor and spending less time working on it which is great. Safe Flying Andrew Good to here some positive comments about Jab engines Andrew . Keep us informed of future developments pls. Bob
Powerin Posted April 17, 2014 Posted April 17, 2014 Good to here some positive comments about Jab engines Andrew . Keep us informed of future developments pls.Bob Umm...they're not Jab engines. 1
Oscar Posted April 17, 2014 Posted April 17, 2014 Yes I have an MGL mini Efis fitted. I have done extensive work modifying the air inlets and outlets on the engine cowls as well as the oil cooler ducting. The highest CHT's I have seen is in climb out during summer. 145 degrees. Normal cruise temp are between 110 in winter and 125 in summer. I have all 6 temps within about 10 degrees. The egt's still have about 40 degrees spread in cruise which I have not done too much about yet.In all I am very happy with Camit's engine and I am looking forward to doing many more hours flying without having any issues. I will keep everyone informed. Safe flying Andrew Very, very encouraging temps there. The work you have done on the cooling airflow is obviously working well and hopefully with information being exchanged amongst owners we will assemble a good picture of what works and what doesn't, and perhaps CAMit can be encouraged and assisted to compile some sort of 'here's a compendium of mods that you might try' guide for people who install their engines. Incidentally, how do you find the MGL? We're planning to use an 'Xtreme' EMS and any advice would be welcomed.
Oscar Posted April 18, 2014 Posted April 18, 2014 Well - an early report from Natfly says the CAMit stand is 'take a ticket' stuff at the moment! I hope we'll get some posts here from people who have made the pilgrimage and viewed the Mona Lisa(s) letting us know what they think. It's easy to be enthusiastic when you have seen the stuff at the factory, but the real test is people bouncing their experiences off Ian Bent and being able to evaluate what work has been done (and why) to fixing the problems they have had. There is nothing better than the exchange of information in a situation where both sides can dig down through the problems and look at them in decent depth, and I have no doubt that Ian Bent will be listening very hard to what people have to tell him. I'm prepared to bet that Ian will return to CAMit with more ideas for improvements, because he is by nature the sort of person who listens to what people tell him. This can only be good for the future of we Jab./Jab-based engined aircraft owners. 1
bexrbetter Posted April 18, 2014 Posted April 18, 2014 They are still connected and full of combustible mixture. A plenum doesn't distribute mixture evenly ( Unless it is gas then it is less likely to separate, but still has to be mixed in the first place). Nev A plain plenum doesn't but they can be woirked to do so and all the majors who supply good V6 and V8 aftermarket intake plenum manifolds do a lot of flow testing in this area with runners that are short or long into the plenum as well as dams and dividers. Many stock V8 manifolds often have small directional dams at the base of the plenum.
facthunter Posted April 19, 2014 Posted April 19, 2014 And a lot that go for max power, just run one induction per cylinder with slide near port throttles. I've used unbalanced (or with balance) siamesed port engines reluctantly and it some point they hardly get any real power out of one or two cylinders , over the whole rev range and are very susceptible to valve overlap. Individual optimised length risers with injectors seems the norm but individual carbs tune easily too. The two carb set-up on the Rotax 912 is not much good either., nor is it on the volkswagens as the firing order is not optimum for single port heads.Nev 1 1
XAIRVTW Posted April 19, 2014 Posted April 19, 2014 They had a stand at NATFLY the engine on display was a very neat & well built engine. Couple of noticeable changes they run a alternator, the base of the barrels are thicker. The was always a crowd at the stand every day I was there & the chap that ran the stand was well informed with his product & even being bombarded by one blokes smart arse questions. My personal opinion I think its a lot stronger engine than the one Jabiru is selling. But the only way to prove it is flight time to see how it will hold.
bexrbetter Posted April 19, 2014 Posted April 19, 2014 , nor is it on the volkswagens as the firing order is not optimum for single port heads.Nev Indeed yet people running around claiming 100hp for Subaru EA81s with the same inherently flawed setup. 1
Bob Llewellyn Posted April 19, 2014 Posted April 19, 2014 Indeed yet people running around claiming 100hp for Subaru EA81s with the same inherently flawed setup. Small horses. Once upon a time I had an overpropped Rotax 503; would not get properly on the pipe at static (or, indeed, below about 25kts...). I fitted a 50mm PVC elbow and about 40cm of straight pipe to one carby; it jumped the chocks... we strangled it, and fitted another inlet runner to the second carby, and fired it up (tied to the scenery, elephants etc). Gutless. More gutless than with no runners. I angled the runner to the front carby, to separate the inlets. Very little change until I had it nearly in the prop, then it roared. So I threw away the plastic and got another prop... 1
Oscar Posted April 19, 2014 Posted April 19, 2014 They had a stand at NATFLY the engine on display was a very neat & well built engine. Couple of noticeable changes they run a alternator, the base of the barrels are thicker. The was always a crowd at the stand every day I was there & the chap that ran the stand was well informed with his product & even being bombarded by one blokes smart **** questions. My personal opinion I think its a lot stronger engine than the one Jabiru is selling. But the only way to prove it is flight time to see how it will hold. Interesting; was the 'smart' person actually asking questions or just in the main telling Ian what his (the person's) opinion was? Questions are good when genuine information is being sought; pretty useless waste of time when they are just a way of forcing one's opinion down everybody's throat. There's plenty of the latter goes on with Jabiru engines.. 2 3
XAIRVTW Posted April 20, 2014 Posted April 20, 2014 Interesting; was the 'smart' person actually asking questions or just in the main telling Ian what his (the person's) opinion was? Questions are good when genuine information is being sought; pretty useless waste of time when they are just a way of forcing one's opinion down everybody's throat. There's plenty of the latter goes on with Jabiru engines.. He was just plan rude he would talk over Ian, Wouldn't allow Ian to finish answering his question. Question are an essential part of these gatherings but you don't have to be down right rude about. I went back to Camit display a couple of times during the course of the day my opinion I think Ian has a good product it just needs time in the air to prove its reliability. 1 4
Oscar Posted April 20, 2014 Posted April 20, 2014 Well, that's unfortunate and no doubt an annoyance for those who would have liked to be able to talk to Ian more usefully. However, it seems to be somewhat of the norm for any gathering of people discussing Jabirus, and quite often, coming from someone who does not actually OWN a Jab. engine but is regurgitating stuff he's heard from 'mates', or on forums etc. as if it's gospel. My co-owner did attend, and deliberately went around talking to as many Jab. owners as he could find, and the general reaction he got was one of 'no significant worries' - including several who were somewhat bemused at the strength of discussion on cooling. Just about all of these had full cht/egt monitoring set-up, and just perhaps it is the fact that they take the trouble to find out what's happening in their engine that they seem to be those with few problems! One Jab. 3300 engined Sonex owner reported that he was entirely happy with his temps, using the standard Jab. cooling inlet set-up, and didn't see what all the fuss was about. 1 1
facthunter Posted April 21, 2014 Posted April 21, 2014 Faster flying aircraft seem to suit the Jab motor. Prop load perhaps? There IS a bit of baiting goes on It's not pleasant for those who are getting a good run out of their engines and don't get much exposure to serious discussion. Quite a few ring me privately. Camit are making a serious attempt to improve a product that is significant in the field, and should be supported. There are NO fit and forget aero engines. Know and look after your engine and you go along way to making your own luck. Nev 3 1 1
Bob Llewellyn Posted April 21, 2014 Posted April 21, 2014 Faster flying aircraft seem to suit the Jab motor. Prop load perhaps? There IS a bit of baiting goes on It's not pleasant for those who are getting a good run out of their engines and don't get much exposure to serious discussion. Quite a few ring me privately. Camit are making a serious attempt to improve a product that is significant in the field, and should be supported. There are NO fit and forget aero engines. Know and look after your engine and you go along way to making your own luck. Nev I wonder how much of the Jabiru cooling story is told by the pressure field around the cooling outlet(s)? Given the std jab cowl outlet location, even between two "identical" Jabs, a slight difference in wing static incidence or control surface rigging could produce a substantial change in outlet zone static pressure; as could a small change in climb speed or climb weight. Moving the outlet rearwards on a Glassair definitely improves things... "Faster flying aircraft" are also low drag, so one would not expect large static pressure fields near the front. Perhaps the simple solution is to cut the noseleg off all Jabirus? Is Thruster.... is good! There is no accident in the position of the Hawker Sea Fury cowl outlets, ditto the Douglas Skyraider, Thorp T-18, P-51 Mustang, DH Mosquito... whereas the early US GA cowl with a hole at the back on the bottom for the hot air to fall out, has very little to recommend it.
Old Koreelah Posted April 21, 2014 Posted April 21, 2014 Bob years ago you got me thinking about this issue. Any low-wing can dump engine cooling air into the low-pressure zone above the wing leading edge. Mine does and the heads run so cool that I have been incrementally reducing the inlet area. 1
Bob Llewellyn Posted April 21, 2014 Posted April 21, 2014 Bob years ago you got me thinking about this issue. Any low-wing can dump engine cooling air into the low-pressure zone above the wing leading edge. Mine does and the heads run so cool that I have been incrementally reducing the inlet area. Sounds good - speaking as a speed freak (who flies Thrusters...), reducing the outlet area as a nozzle should give a bit of "thrust", provided you don't increase the positive pressure field around the inlet. Anyway, reducing the cooling flow certainly reduces the cooling drag.
Oscar Posted April 21, 2014 Posted April 21, 2014 I wonder of anybody has ever looked at the CHTs on a Jab with the front wheel spat vs no spat.
Bob Llewellyn Posted April 21, 2014 Posted April 21, 2014 I wonder of anybody has ever looked at the CHTs on a Jab with the front wheel spat vs no spat. Good question. At a guess - and it's just a guess - the spat is far enough below the cowl outlet for the effect to be small. For reference, the DC-3 fuselage was found to increase the nacelle (engine) drag by ~11% or so... and those engines weren't terribly close to the fuselage!
Old Koreelah Posted April 21, 2014 Posted April 21, 2014 ...reducing the outlet area as a nozzle should give a bit of "thrust", provided you don't increase the positive pressure field around the inlet. Anyway, reducing the cooling flow certainly reduces the cooling drag. A few years back I had my hot exhaust squirting into the mouths of a pair of exhaust augmenters (based on 1942 NACA research). They worked well, sucking cooling air past the engine and making a measurable difference to climb performance. The penalty was black muck over the wing root and $1070 dollars for an ANR headset. I removed the augmentors. The 3-4% extra efficiency was not worth the damned noise. 1
deadstick Posted April 21, 2014 Posted April 21, 2014 For Anyone that was at Natfly and attended the Camit stand: - what's the cable system bolted to this 3300 crank case?
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