Jab engines

[Old Koreelah]

I run a battery isolator mounted under the panel. 1/4 turn to disconnect. It serves to stop any possible battery leakage as well when hangared.

If it's the type I used, it's prudent to completely remove the key, rather than simply leave it in the off position.

 

I installed one on my Guzzi because it had a current leak I couldn't track down. I thought I'd be smart by having the red plastic key turned about 90 degrees by a lever concealed under the side cover. Several times it drained the battery, even though turned off.

Turns out that, even in the off position, it only takes a slight pressure on the plastic key to make a connection.

[Mhalc]

Be very aware of the weight of the new prop Mhalc.

In addition to the weight of the CS prop, I am adding an additional 9.5lbs to the back of my Gen 4 3300. I have worked out the design, and started fabrication of a supercharger mount and drive assembly. I hope to complete the mount/drive assembly and start testing on a test stand in the next few weeks.

 

[tillmanr]

If it's the type I used, it's prudent to completely remove the key, rather than simply leave it in the off position.

 

I installed one on my Guzzi because it had a current leak I couldn't track down. I thought I'd be smart by having the red plastic key turned about 90 degrees by a lever concealed under the side cover. Several times it drained the battery, even though turned off.

Turns out that, even in the off position, it only takes a slight pressure on the plastic key to make a connection.

Yes, I do as a part of shut down.

[Yenn]

I have a switch to completely isolate the battery. That stops any fire problems, or leak down problems. The same as mentioned above I think. I installed the same switch on the RV4 I built and was always amazed how the majority of Rvs using a solenoid operated master switch, which needs power to it even when the master is off.

[Bruce Tuncks]

Wow Mhalc, this might be the first supercharged Jabiru. It sure will be interesting to see how it goes. Good luck with the project.

I know of a guy who daydreamed of just such a thing when he was at 14,500 ft and his Jabiru ran out of puff.

[Flightrite]

Super chargers cost power to make power hence you see very few in the aviation game.

[Old Koreelah]

Wow Mhalc, this might be the first supercharged Jabiru. It sure will be interesting to see how it goes. Good luck with the project.

I know of a guy who daydreamed of just such a thing when he was at 14,500 ft and his Jabiru ran out of puff.

I dimly remember a videoclip from the US of a bloke installing a turbo on his 3300 Jab engine.

[Blueadventures]

Bruce I'll be installing an LED near my key to show when the starter is getting juice.

I have an automatic battery isolator near my right knee. A weighted lever connected via a wooden rod to the battery's earth pole; any sudden forward or downward acceleration disengages the power.

I have on a long flight accidentally disconnected the battery by hitting it with my knee; no drama, engine keeps going, just a few instruments drop out.

Hi OK and BT this is where I mounted my LED (Towards top left of image - Amber) and its a push to test as well, worthwhile addition as if ever the starter remains engaged it will over heat (usually destroy themselves) and suck the battery dry (usually damage or destroy the battery) and therefore usually results in cost and maintenance to starter and battery etc. Rarely happens; but has and does so the LED will prevent the inconvenience and costs).

 

[Mhalc]

I dimly remember a videoclip from the US of a bloke installing a turbo on his 3300 Jab engine.

I tossed around the turbo idea for my Gen 4 3300, but the exhaust heat added under the cowling and exhaust back pressure/heat on the valvetrain lost out to the simpler supercharger. I did add a twist, an electrically controllable blow-off-valve and small controller to provide variable (user defined) boost profiles. Very much like a turbo-normalized engine without the excess hear under the bonnet.

[Mhalc]

Wow Mhalc, this might be the first supercharged Jabiru. It sure will be interesting to see how it goes. Good luck with the project.

I know of a guy who daydreamed of just such a thing when he was at 14,500 ft and his Jabiru ran out of puff.

Thanks for the well-wishes. As an engineer I know the devil is in the details, BUT the proof is in the testing. Where I fly in the southwest US I climb to 9,000’ or more to go on any x-country to get over the mountains.

[brinykraut]

Forgot to mention in that last post...

 

The starter Bendix cover developed a crack at 50 hours. It was cast, as much of the Gen 4 is now. Jabiru replaced it with a CNC cut cover. Then the Bendix itself failed to engage properly and they replaced that on warranty.

 

John M

Had identical issue with the cast cover on my Gen 2 2200 at--~50 hrs! Jab US sent the machined replacement.

[horsefeathers]

Hi OK and BT this is where I mounted my LED (Towards top left of image - Amber) and its a push to test as well, worthwhile addition as if ever the starter remains engaged it will over heat (usually destroy themselves) and suck the battery dry (usually damage or destroy the battery) and therefore usually results in cost and maintenance to starter and battery etc. Rarely happens; but has and does so the LED will prevent the inconvenience and costs).

 

 

Hey Bluead

 

Any chance of posting a simple mudmap (hand drawn would be fine) of your led circuit please?

[dlegg]

I tossed around the turbo idea for my Gen 4 3300, but the exhaust heat added under the cowling and exhaust back pressure/heat on the valvetrain lost out to the simpler supercharger. I did add a twist, an electrically controllable blow-off-valve and small controller to provide variable (user defined) boost profiles. Very much like a turbo-normalized engine without the excess hear under the bonnet.

If going down the blown engine route you will need to entertain the idea of fuel injection. That bing simply won't do the job. Then of course you will have excess heat to take care of. Your electrical system will have to reflect the changes, Rotec make an alternator mount and pulley for the jab. I wish you well on your endeavour.

[Blueadventures]

Hey Bluead

 

Any chance of posting a simple mudmap (hand drawn would be fine) of your led circuit please?

Connect the LED positive wire the solenoid terminal that supplies power to starter. Other to ground. That way one when starter circuit energised it will be lit. If you use a push to test type lamp same plus the push to test connect is wired to a 12 volt source. Cheers

[Mhalc]

If going down the blown engine route you will need to entertain the idea of fuel injection. That bing simply won't do the job. Then of course you will have excess heat to take care of. Your electrical system will have to reflect the changes, Rotec make an alternator mount and pulley for the jab. I wish you well on your endeavour.

As for the fuel injection/electronic ignition I wanted to preserve the Jabiru’s traditional aircraft engine approach with fixed timing simplified fuel delivery. I do have an AeroCarb and Rotec TBI which I plan to test with in addition to the Bing. The AeroCarb being only 35mm will be the least likely to keep up with the ~220CFM boosted flow rate, but the Rotec and Bing being 40mm should be fine at this modest boost rate. The boost control computer and electrically controllable boost regulator valve require less than 2A’s, that combined with my current power load, keeps the total well below 20A’s, not sure why I need a bigger alternator. As for heat, flight tests will tell the tail, but my gen 4 is running well below the continuous limits now and thermodynamic calculations keep me below these limits as well as well below the knock limit.

 

The devil is in the details, but the proof is in the TESTING :).

[jetjr]

I understood, the 40mm Bing was near max flow for the 3300, Jab were testing a twin setup

Could be part of the problem with uneven fuel distribution across cylinders at differing throttle settings

If you don't sort this out, any increase in induction pressure will make problems more serious

A SDS port injection system can be used with Bing as backup, with the dual controllers you can vary each cylinder fuel flow - BUT $$$$$

[facthunter]

Having a "blower" downstream of a carb helps to distribute the fuel mix more evenly. You are adiabatically heating the induction air and loading the engine to drive the blower as well. Most decent sized Radials have blowers many of which are variable speed driven for higher altitudes. More power from the engine the more heat it has to disperse. A Water Methanol injection for the TO power may help. It will probably reduce carbon build up as well. I once owned a Twin Commanche that was factory fitted with Turbochargers as it regularly operated over the Rockies near the Canadian border in the west . Even though it only restored ground Sea Level performance at height the whole motor was beefed up from the "normal" engines. fitted. Nev

[Mhalc]

Having a "blower" downstream of a carb helps to distribute the fuel mix more evenly. You are adiabatically heating the induction air and loading the engine to drive the blower as well. Most decent sized Radials have blowers many of which are variable speed driven for higher altitudes. More power from the engine the more heat it has to disperse. A Water Methanol injection for the TO power may help. It will probably reduce carbon build up as well. I once owned a Twin Commanche that was factory fitted with Turbochargers as it regularly operated over the Rockies near the Canadian border in the west . Even though it only restored ground Sea Level performance at height the whole motor was beefed up from the "normal" engines. fitted. Nev

In my case the carb/TBI is downstream of the supercharger, and between the SC and carb/TBI is an electrically controllable blow-off-valve (BOV). A small computer (boost controller) controls the position of the BOV to regulate the boost levels into the carb/TBI. The user can configure the boost level from 30” to 42” of MAP (testing will establish the practical maximum). So one options would be to operate the SC as a “normalized” engine with SL HP to ~16,000’ or boosted power to ~10,000 then dropping back to SL HP at ~16,000’.

[facthunter]

It all depends on how well your engine can dissipate the extra heat, because it's definitely there to contend with. The Lycoming engines I described were also equipped with oil jets to the bottom of the Pistons.. Pretty large modifications when the MAX horsepower was never exceeded. When you pressurise the carburettor as well you are involving a lot of flammable mixture and a lot of damage when a back fire is considered and you can never completely rule out such a possibility. Nev

[Bruce Tuncks]

Has a jabiru engine ever been modified to make a longer pipe between the carby and the individual cylinder take-offs?

The sole purpose of this pipe would be to even out the mixtures as seen by the different cylinders.

[kgwilson]

Do you mean modifying the intake manifold? I don't know where else you could put it. The carb is attached to the rear of this & intake pipes feed the cylinders individually from the manifold. In the 3300 the pipes to cylinders 1 & 2 are a lot longer than to cylinders 5 & 6. On my engine cylinder 6 runs richer than any of the others with the plugs always black while the other 5 are considerably cleaner. I've fiddled around with the carb orientation and have a vane in the cobra head to direct air and have it so egts are pretty much the same on both sides but have never been able to get No 6 to run as lean as the rest so I gave up & anyway the engine runs as smooth as silk.

[facthunter]

Flowing inlet tracting is a dark art if you are trying to get even mixtures. You can try to match pulses lengths or the join angles. Never works. The best way is a carb to each cylinder OR individual injection. The Rotax 912 is one of the worst setups possible The pulsing is as wrong as it can be. The only good feature is it's short length and that means less combustible mixture if a backfire happens which is a much more damaging thing than most realise. Nev

[Flightrite]

Flowing inlet tracting is a dark art if you are trying to get even mixtures. You can try to match pulses lengths or the join angles. Never works. The best way is a carb to each cylinder OR individual injection. The Rotax 912 is one of the worst setups possible The pulsing is as wrong as it can be. The only good feature is it's short length and that means less combustible mixture if a backfire happens which is a much more damaging thing than most realise. Nev

 

For an engine that is "one of the worst" there's an awful lot of them!?

[facthunter]

I said the MANIFOLD is one of the worst... Happy to answer for what I actually say. Nev

[Red]

Should I close the Jab Engines group?, it seems to be superflous with 99% of activity in this thread.

Probably better to keep all the info in one place....what you think?