Jab engines

[Yenn]

We have had a load of waffle about Jab engines and the thread drift is going on all the time. Here is your chance to say what you "know" about Jab engines.

I have a 2200 Jab in a Corby Starlet, it runs well although I got poor mogas and busted a piston with detonation. Avgas is the go for me. I would like to try a different carburettor from the Bing, although the Bing runs fairly well.

Don't bother talking about the engine if you don't run one or regularly fly one.

[turboplanner]

We have had a load of waffle about Jab engines and the thread drift is going on all the time. Here is your chance to say what you "know" about Jab engines.

I have a 2200 Jab in a Corby Starlet, it runs well although I got poor mogas and busted a piston with detonation. Avgas is the go for me. I would like to try a different carburettor from the Bing, although the Bing runs fairly well.

Don't bother talking about the engine if you don't run one or regularly fly one.

There is a very significant difference in specification between the new Gen 4 engines and the previous engines, and just lumping them all together is likely to create total confusion.

[jetjr]

And no definitive break between the "Gens" although the latest is by far the biggest change in one move

[kgwilson]

Mine is a Gen3 3300A. Always run on Mogas. Originally I used BP 95 but that has become difficult to obtain as the BP stations around here no longer supply it but have in its place 94 which has ethanol in it so I switched to 98 which I get from a petrol station just around the corner from the aerodrome & it is a busy station on a main road. Starts first time every time, runs smooth and the engine is clean. I change the oil (3 quarts) & filter every 25 hours with Shell W100 plus. The oil stays fairly clean & I never have to top up between changes. I've used Avgas only once when away as that was all I could get. I didn't notice any difference.

 

I just completed a 100 hourly & the compressions are 75 - 80. I got a miss after 2 hours running & traced it to a dud new plug. I like the engine for its simplicity and easy maintenance & it is direct drive. Getting the mixture right on both banks has been a tricky exercise with one side running slightly richer than the other. I put a vane in the cobra head which I can bend in order to direct air and getting this spot on is a mission so I have given up. I only monitor CHT on 1 cylinder & have moved it around but the difference is relatively small & I monitor EGTs on the rear 2 cylinders only. My engine runs quite cool & the EGTs are very close. I get 18-20 lph cruising at low altitude at around 2800 rpm. Up high 6-8000 plus it is around 24 lph at 2850-2900 rpm

[Old Koreelah]

My early hydraulic-tappet 2200 is going well after a dozen years. It runs well with good leak-downs and fairly even temperature spread on heads and exhaust gas. Mine is fed AvGas and I don't mind paying the extra to know it's getting clean fuel. It starts easily and purrs away for hours without a worry.

 

I love this engine because it's simple and has the best power to weigh ratio available in that class.

Without Jabiru engines, lots of us could not afford to fly.

[Roscoe]

My 2200 Gen3 is running fine on Avgas since new in 2014.

Leakdowns all good and am getting 14 lph in cruise at around 2850 RPM.

Oil and filter change every 25 hours using Shell W100 Plus and little or no oil between oil changes.

Maintenance always in accordance with the Jabiru Schedule.

Smooth and quiet, no complaints.

[kgwilson]

In the 2018 Annual report from Ra-Aus there were some interesting stats. They did not produce such a report in 2019

The following are the numbers of 3 axis aircraft on the register for the top 10 brands

 

Jabiru 886

Thruster Aircraft 216

I C P 184

Tecnam 186

Aeroprakt 159

Austflight ULA 158

Skyfox Aviation 133

Howard Hughes Engineering 128

Zenith Aircraft 103

Rand 67

 

This will of course have changed somewhat in the last 18 months but it does show there are a lot of Jabirus out there. If you add the VH registered Jabirus and all of the other aircraft flying with Jabiru engines, I would guess that there are at least 1200 Jabiru engined aircraft in Australia which is not an insignificant number.

[Thruster88]

Great to see thruster in 2nd place in 2018, the rotax 2 strokes are either friggin awesome ( I think they are) or owners are not reporting failures.

 

By far the biggest active fleet in Australia is powered by lycoming and Continental, way more than 5000 aircraft some with two engines and almost zero in flight failures, that is a benchmark to compare your favourite engine to.

[FlyBoy1960]

Dont dream about the engines, give hours operating for your comments to be valid please

[turboplanner]

Dont dream about the engines, give hours operating for your comments to be valid please

You can get details over a lot of years, so a big sample from this link: Accident and defect summaries - RAAus

Click Filter and enter the name you want to search on.

You can see what happened in flight and what was found after landing.

People often complain there's not enough detail here, but you can only get what the owner enters.

Over the years I've found the reports good for statistics.

[Bruce Tuncks]

I think my engine might have been the first with an oil cooler supplied as standard. It was bought in 1998, and has run fine in the air ever since. The 2 rear cylinder heads are the next iteration and were about 2003 manufacture. I changed them over because the old rear heads were running too hot, and the later model heads had substantially more fin area. Yes, the rear heads are different from the front ones. It has the old 32mm carb.

After about 20 years, the EGT's and the CHT's are finally running fairly equal. This was the end result of monitoring all 4 cylinders , thanks to jab 7252's expertise and Arduino for making an affordable computer system.

The engine has always run on avgas because that is what we have in the bowser.

[Guest Machtuk]

I run 95 RON in my 2200A with flashlube, change oil/ filter every 20 hrs (cheap) several hundred hrs runs like a Swiss watch as I never run it beyond 3000 rpm?

[Yenn]

Wow. Where are all the knockers?

[pmccarthy]

Wow. Where are all the knockers?

On the Big Boobs porn site.

[Paul davenport]

Happy with my 230 now I have the mixture and cht problem sorted. A pilot up the valley has a 160 apart from servicing no problems and he has around 600 trouble free hrs all leak downs in the 70s plus

[coinz]

We have had a load of waffle about Jab engines and the thread drift is going on all the time. Here is your chance to say what you "know" about Jab engines.

I have a 2200 Jab in a Corby Starlet, it runs well although I got poor mogas and busted a piston with detonation. Avgas is the go for me. I would like to try a different carburettor from the Bing, although the Bing runs fairly well.

Don't bother talking about the engine if you don't run one or regularly fly one.

I run my 3300A on 98,after modding the ducts it ran at a too cool 245F as i realized after 30 hours plugs were always black even after repeated

cleaning,did some carb tuning ended up dropping the needle and changing out the main jet temps have risen to 255F,after 2 oil changes using

Camgaurd am going to W100+ as recommended here,

the thing i don't get is why did Jab changed out all those cylinder heads seems like a lot of expense,when i could simply redo my ducts and end up

with a motor that ran "too" cool? Ducts,cut horizontally,lifted 15 at front,30mm at rear,extended at rear i can squeeze fingers into rear gap,aids

airflow to the rear,yes i have read all the stories on closing these gaps ,i disagreed then and still do.

Gaps between cylinders,i tried alu strips,yes they soon cracked,replaced those with extended fibeglass strips that were angled in and when set

hold in place by pressure.

Seems to me the ducting should have been better investigated.More volume and allow more cool air flow through too the rearmost cylinders.

Other issues i have with this motor,rocker bearing shafts appear very small diameter,rockers as far as i can tell have no spring to control side movement,

i can move the rocker sideways and easily hear clicking,i have 2 hours till next oil change,valve clearance check so i will investigate this more

thoroughly, but do these engines have any reputation for higher than normal rocker wear.I will back the adjusters right

off and check for bearing to shaft wear.Is it all the same in the Gen 4?,or have they gone to a hollow and bigger bearing area.

cheers

colin

[facthunter]

There's "normal" wear and galling type wear, where the oil film fails. Wear where the oil contains dust or metal particle will accelerate wear. Without these factors wear is usually quite low. Bigger wear surfaces reduce load but adequate is enough if it doesn't fail. Nev

[tillmanr]

I run my 3300A on 98,after modding the ducts it ran at a too cool 245F as i realized after 30 hours plugs were always black even after repeated

cleaning,did some carb tuning ended up dropping the needle and changing out the main jet temps have risen to 255F,after 2 oil changes using

colin

I believe that the plugs will always be black/brown running unleaded. Only grey if running leaded..

[facthunter]

Idling mixtures are always richer and the plugs only get hot enough to evaporate the soot on high throttle openings. Plug readings are only valid if the engine's cut at a high throttle setting and not allowed to idle. This is impractical with aircraft and was mostly used with motorcycle race engine tuning. Aero leaded fuels have agents (chemicals) to reduce the lead fouling that makes the exhaust pipes white on the inside if the mixture's lean enough. Nev

[Bruce Tuncks]

Coinz, 245F is too cold I agree. Was this the max on climbout? How was it measured? I have never heard of such a cold running Jabiru (or Lycoming) engine.

While I can't argue with the results, I can't see how any air which doesn't come into contact with the hot metal removing any heat. I imagine hot engine molecules vibrating strongly causing adjacent air molecules to be shot away, taking energy from the engine with them.

Please don't be offended by my questions, I am quite capable of being wrong. Gosh, it has taken me 20 years to get the 4 temperatures fairly equal in my old 2.2 engine.

[Yenn]

Air should remove heat, even if it doesn't come in contact with the metal. It absorbs heat from the adjacent air that does touch the metal. The actual amount of air in contact with the metal is very small and probably not moving very fast due to surface friction.

[M61A1]

Wow. Where are all the knockers?

You eliminated them when you said only owners or operators could respond. A bit like saying you can’t knock a Hilman Hunter unless you own one.

Of course none of those who bought one will denigrate them, although there was someone on this site a few years ago that used to regularly voice their displeasure about how often the Jabs at his flying school broke.

[turboplanner]

Of course none of those who bought one will denigrate them, although there was someone on this site a few years ago that used to regularly voice their displeasure about how often the Jabs at his flying school broke.

That included one or two which failed on the flight home from Bundaberg, and the reason for that is that the issues were intermittant; they occurred at all sorts of hours in all sorts of applications with all sorts of maintenance skills. Those are the hardest issues to solve because you can't pre-set a maintenance regime to replace the part before the engine is likely to stop, and the manufacture can't quickly pinpoint the issue and come out with a kit or a change of oil specification etc. What Jabiru did with the Gen 4 engine is give operators the chance to go to a new product and still be below the Competitor's cost.

Intermittant means that many of those engines will never have a problem, so it's not surprising there are good reports.

[Paul davenport]

At Narromine last year Jabiru had a new head in development as a replacement for the Gen 1,2,3 series motors, looked identical to the G4 motor heads but held on with bolts. This head is being test

You eliminated them when you said only owners or operators could respond. A bit like saying you can’t knock a Hilman Hunter unless you own one.

Of course none of those who bought one will denigrate them, although there was someone on this site a few years ago that used to regularly voice their displeasure about how often the Jabs at his flying school broke.

I suspect the reason that non owner operators were asked not to reply was to stop drift and,

hear say advice. No one can stop you from commenting but your comments carry very little credence

[Bruce Tuncks]

Conduction, convection (free or forced ) and radiation are the only ways to transfer heat.

If delta T=100C, A=.5sqm, delta x=1cm then my calculation of the heat transfer is: Forced convection=25kW and conduction= 130 watts through 1 cm.

So the cooling of an air-cooled engine is mainly forced convection. Air is of very low conduction which is why thermal insulation consists of air-containing stuff.

Radiation is also trivial. Feel free to check these calculations via google. I used 505W/sqm-K as the midpoint forced convection coefficient.