EGT's on all cylinders of a Jabiru engine

[Captain]

I note J430's recent post titled EGT & CHT, however having just done an approx 9 hr round trip of Wagga/Mildura/Gawler/Swan Hill/Tocumwal/Wagga I wonder whether anyone else here has EGT readouts on all of their cylinders and who would be interested to share some figures, particularly to compare results and look at which are the warmest and what are the differences across them all.

 

 

[Captain]

Thanks Kev,

 

 

 

It would be a big help if he will allow you to post them.

 

 

 

Mine is hottest on #2. If possible, please see if your friend has the same thing and by how much it is up on the others.

 

 

 

Regards Geoff

 

 

[Guest J430]

It is most useful to have both EGT and CHT.

 

As Captain points out his EGT (I assume) is hottest on No2, and its probably the leaner of the cylinders, but his CHT may be cooler.

 

The post I placed of the C210 was of a pretty good bit of gear, trying to run it LOP provided rough running and via the data of CHT and EGT the "Rocket Scientist" we had driving was able to deduce faulty plugs in No1 cylinder.

 

Have fun!

 

J

 

 

[Captain]

And a supplementary question ..... has anyone seen a recommendation from Jabiru on which cylinder they suggest to install an EGT gauge on a 3300 if you are only having one EGT sensor?

 

 

[Guest J430]

Captain

 

With the new exhaust being individual extractors........I would say one in each!!!!:big_grin:

 

The old manifold made it possible to use one per bank.....and you got an average, but I do not know. They will all be different and vary load to load day to day RPM etc.......

 

So really the only way id to fit a Dynon engine display or an EDM 700 or 800 I guess.

 

Or just not worry!

 

Fly it with 2850-2900 RPM and enjoy the view!

 

J

 

 

[Captain]

So really the only way id to fit a Dynon engine display or an EDM 700 or 800 I guess. Or just not worry! Fly it with 2850-2900 RPM and enjoy the view! J

Thanks for all the little wisdoms.

 

 

 

I have Dynon with 6 EGT's and that is why I want to understand the results better if anyone else also has 6 sensors.

 

 

 

The reason for the suppl. question is that J often fit a single sensor for CHT & one as an optional EGT. I understand that they fit 'em on what they have proven to be the hottest cylinders (and I also assume not both on the same), so what I was asking was which ones do J fit 'em on. I guess that you don't have such a set-up.

 

 

 

Always will enjoy the view.

 

 

 

C

 

 

[jetjr]

CHT #2

 

Bit late but yes #2 is the hottest

 

Left bank is usually hotter than right

 

Jabirus idea is that so long as they reduce in cruise no real problem but did recommend fitting flow straightner in carb inlet to even out distribution in plenum

 

Anyone done it?

 

JR

 

 

[Guest J430]

I am going to move my CHT at the next service......No2 would not surprise me!

 

On an IO550 in a C210 of late it has been on a cylinder you would not expect also. Not Just the Jab it seems.

 

Come on Captain, you have all the gear and seem more than talented enough to do the job, shoot some pics and post 'em.

 

J:thumb_up:

 

 

[Captain]

J

 

 

 

My EGT is hottest on #2, assumedly due to natural bias in the length of the inlet and some selective flow in the plenum ..... (need to know more about the carb inlet flow straightener that JR is talking about).

 

 

 

CHT is hottest on #3, assumedly because it is stuck in between #'s 1 & 5 and airflow isn't quite as good on that side, as indicated by JR, I assume due to prop wash.

 

 

 

Will see what datalogger downloads I can post, as advised on the other thread.

 

 

 

Regards G

 

 

[Guest J430]

Agreed

 

CHT and EGT are two unrelated animals.

 

I too am keen to learn more about this intake thing!

 

J:wave:

 

 

[Guest brentc]

I assume that you are referring to the Jabiru 'Cobra Head' that is fitted to replace part of the intake scat hose?

 

 

[jetjr]

Yep the intake pipe into the carb, I havent even had a look at mine yet so dont really know whats involved

 

Data from my D180 in J200

 

CHT - 137,160,122,144,110,107

 

EGT - 689, 677, 643, 660, 654, 635

 

Cruise 2800rpm, 3500ft, 13 deg OAT, 119 TAS

 

Jab reckon CHT below 170 is OK but my span is a bit wide

 

EGT 700 max

 

Only relevant in cruise, bit over this for 5 min climb is OK.

 

What do thers reckon?

 

JR

 

 

[Guest J430]

Are you in SEQ by any chance? Would love to check this out more! And how are your CHT rings mounted?

 

I am thinking I might fit one on the No 2 head........might scare me more likely! from the rear left cyl I get 270F/132C on average.

 

Cheers!

 

J:thumb_up:

 

 

[jetjr]

No sorry Cent NSW

 

I just had one fiited to #6 for 500hrs, after fitting cowl extensions it got really hot

 

Hate to think what #2 was doing then

 

Ive now fitted D180 and all six monitored.

 

Great device and getting cheaper by the week. I bought it @ $0.79 AUD

 

JR

 

 

[jetjr]

2nd part

 

CHT rings mounted as per Dynon reccommendations, between plug and gasket washer - I will probably not do this again but mount directly to head under washer as getting these washers off damages them

 

JR

 

 

[Guest J430]

I use the NGK Irridium DR9EIX plugs and the compression washer just unscrews. Have not had any drama so far......famous last words!

 

J

 

 

[Bruce Robbins]

From the matronics forum. Not a jabiru airframe, but sheds some light on the uneven inlet distribution none the less.

 

Bruce

 

Oct 23 2005

 

 

Cooling improvements on the Zenith 601HDS w/Jabiru 3300

 

 

During my first few hours of flight, I experienced elevated cylinder head temperatures on my Zenith 601HDS with Jabiru 3300A engine. Also had issues with Exhaust Gas Temperature imbalance at full throttle. The following is a summary of changes made to improve the situation. This really just builds on the recommendations of Jabiru and Zenith to provide plenty of cooling for the 6 cylinder engine. I would like to thank Jeff Small, Fred Hulen, Stan Challgren as well as Pete Krotje at US Jabiru and Andy Sylvester at Sun Coast for their contributions. As a place to start, US Jabiru provides some good cooling suggestions at their website:

 

My aircraft has the following modifications:

 

 

1) Fuel Economy Carb Kit as supplied by Jabiru.

 

 

2) Gull wing baffles between cylinders as recommended by Jabiru

 

 

3) Full deflectors angled down between the spark plugs of cylinder #5

 

& #6 as recommended by Jabiru.

 

 

4) Smaller deflectors angled down between the spark plugs of #3 & #4. These middle cylinder deflectors usually need some tuning. Would suggest starting with 3/4" tall. On #3, I stayed at 3/4", on #4 ended up trimming down to 1/2".

 

 

5) The inlet to the ram air ducts has a gap between the duct and the cylinders at the bottom. This allows air to escape downward without doing any useful work. I added some .025" aluminum plates that butt up against cylinder's #1 & #2 to prevent this from happening. To reduce the over cooling of the front two cylinders and force more air upward to the rear cylinders, I angled the material upward about an 2-3??. The exact height needs to be determined by trial end error. The new XL cowl has openings that are quite small and located high on the cylinders. My modification attempts to duplicate the XL cowl openings and seems to work quite well. At the onset, this change appears to be counter-intuitive. Just keep it mind, the goal is to get as much use out of every air molecule as possible!

 

 

6) Small baffles mounted between valve tappet covers. This prevents

 

more air from escaping without doing any useful work.

 

 

7) There is a temptation to add an L angle to the bottom rear of each ram duct. I tried this change and it elevated my temps rather than reducing them.

 

 

8) The oil cooler inlet is keep quite small to allow more air to find it's way through the cylinders. I ended up with about a 1.75" x 4.00" opening. The Jabiru website provides a good discussion on this. I tried a much bigger opening as can be seen in the picture and it provided very

 

little benefit.

 

 

9) Don't forget to keep your oil level midway between the Full and Add mark. Jabiru indicates that overfilling can cause high oil temps.

 

 

10) My #1 cylinder was running much cooler than the #2 cylinder with identical intake openings. I rotated the bottom of the carb 5-10 degrees towards #1 and that took care of it. The main jet feeds the carb at the bottom so if the carb is tilted, it can direct more fuel towards one bank of cylinders than the other.

 

 

At full throttle, EGT's from left to right bank were 150 F different. I suspected that air entering the carb through the 90 degree intake elbow was piling up on the outside of the curve. I installed a vertical divider in the elbow to keep left side air separated from the right side air. This worked beautifully. My EGT's are now balanced within roughly 50 F at all throttle settings including WOT. The divider was fabricated out of a piece of 6061T6 aluminum - 5.25" x 3" x .016". The upper and lower edges were rolled around a 1/16" cable to add stiffness and prevent cutting of the rubber elbow. Finished height is just slightly over 2.25 inches so it fits snuggly within the elbow. After rolling the edges, the part was bent 90 degrees to fit the elbow contour by wrapping around a 2" diameter plastic pipe. After it springs back, you end up with a 2" bend radius which is equivalent to the center radius of the elbow. Once the part is finished, the cable can be removed (prevents a potential corrosion issue). The rubber elbow is quite pliable in the free state, so the flow divider installs quite easily. After installation, the divider is trapped pretty well in all directions.

 

 

With the Aid of my Engine Information System from Grand Rapids Technology, I was able to monitor my progress for each Cylinder Head Temperature: I now have the following readings at 60 F ambient temperature (my engine has 28 hours TT, so temps have fallen after break-in):

 

-------------------------------------------------------------------------------

 

RPM IAS CHT1 CHT2 CHT3 CHT4 CHT5 CHT6 EGT5 EGT6

 

 

-------------------------------------------------------------------------------------

 

2600 110 247 228 259 247 272 245 1465 1423

 

2700 120 242 221 253 239 265 240 1486 1451

 

2800 125 242 226 252 242 265 244 1512 1498

 

2900 130 253 246 260 260 268 262 1482 1538

 

WOT 138 288 293 293 298 301 297 1463 1482

 

 

-------------------------------------------------------------------------------

 

 

This was a quickie test and temps/speeds were not totally stabilized. Oil temps varied from 200-230F depending on Throttle setting. This is an area where a NACA inlet could improve Oil Cooler efficiency. The new XL cowl incorporates one of these. The Flight Test was run at 3500 ft MSL and an ambient of 60F. Wheel pants and gear fairings are installed with an otherwise stock airframe.

 

 

The Jabiru is running very nice. I'm happy with the installation, power and smoothness after getting through these initial teething problems. Fuel burn at lower cruise settings is estimated at a miserly 4 gph. With the fat wing, I suspect fuel burn will go way up at the higher cruise speeds.

 

 

Chuck Long

 

Zodiac 601HDS

 

N601LE, 28 hr TT