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EGT probes

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jbuseman

Joined: 04 Feb 2010
Posts: 5
Location: Iowa

Posted: Tue Mar 08, 2011 1:19 pm Post subject: EGT probes

Hi guys I am looking for some opinions on where to put some temp probes on the M-14. I am using the Dynon Skyview which allows me up to 14 probes in any variety. Just looking for suggestions as to how you would divide them up ex. 9 EGT/5 CHT or 9CHT/5EGT or any other such arrangement.  Also which cylinders would be most desirable to have the probes on. Is it typical on the engine to have certain cylinders run hotter than others?  My engine is Fuel Injected. Thank you.

viperdoc(at)mindspring.co
Guest

Posted: Tue Mar 08, 2011 2:07 pm Post subject: EGT probes

The top three cylinders typically run the hottest. As to how to do the probes, I don't feel qualified to answer that. One of the engine guys can give a better answer than I can.

Doc



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mark.bitterlich(at)navy.m
Guest

Posted: Tue Mar 08, 2011 2:37 pm Post subject: EGT probes

Ummm.... when you have time, could you please tell us exactly what fuel

injection you have, where you got it, and how well it performs? 



THANKS! 



Mark Bitterlich

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radiopicture

Joined: 23 Jun 2008
Posts: 263

Posted: Tue Mar 08, 2011 5:09 pm Post subject: EGT probes

One thing to be careful of is proper drilling and de-burring of the the hole for the bayonet EGT probe. Failure to do so can result in exhaust cracks. It's fussier than you might think.



On Mar 8, 2011, at 4:20 PM, jbuseman wrote:



 	  Quote: 	
		   

 

 Hi guys I am looking for some opinions on where to put some temp probes on the M-14. I am using the Dynon Skyview which allows me up to 14 probes in any variety. Just looking for suggestions as to how you would divide them up ex. 9 EGT/5 CHT or 9CHT/5EGT or any other such arrangement.  Also which cylinders would be most desirable to have the probes on. Is it typical on the engine to have certain cylinders run hotter than others?  My engine is Fuel Injected. Thank you.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=333249#333249

keithmckinley

Joined: 11 Aug 2008
Posts: 434

Posted: Wed Mar 09, 2011 6:37 am Post subject: Re: EGT probes

Cracks my not be much of an issue if you do it the right way and have a threaded bung welded on the exhaust.

keithmckinley

Joined: 11 Aug 2008
Posts: 434

Posted: Wed Mar 09, 2011 6:38 am Post subject: Re: EGT probes

Cracks my not be much of an issue if you do it the right way and have a threaded bung welded on the exhaust.

radiopicture

Joined: 23 Jun 2008
Posts: 263

Posted: Wed Mar 09, 2011 12:09 pm Post subject: EGT probes

A bung (like a flange?) instead of a clamp on the exhaust... Which sounds great.... However, welding the titanium exhaust is tough. For one thing, the titanium rod you need to use is nearly 100% titanium. As Al Neri would say: "Difficult... not impossible." The ones I've seen use the hose clamp method... obviously not as classy.

On Mar 9, 2011, at 9:37 AM, keithmckinley wrote:



 	  Quote: 	
		   

 

 Cracks my not be much of an issue if you do it the right way and have a threaded bung welded on the exhaust.

 

 --------

 Keith McKinley

 700HS

 KFIT

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=333305#333305

mark.bitterlich(at)navy.m
Guest

Posted: Wed Mar 09, 2011 12:26 pm Post subject: EGT probes

Ok... Just being curious.  



Are we saying here that there is less of a chance of a crack, in a

titanium exhaust system, if we totally remove the whole exhaust, take it

over to a welding shop, weld in a threaded bung ... and just a

second.... what type of metal threaded bung are we going to weld INTO

this exhaust?  What is the metal composition of the bung?  Dissimilar

metal issues?  And then by the way, when you weld into that exhaust

pipe, it tends to just blow up in smoke unless you get a REALLY REALLY

good welding shop (I've seen this happen with my own eyes when the

threaded smoke bung in a Sukhoi had to be repaired) ... and we are doing

this to all NINE exhaust pipes..... 



And this is being done instead of: 



Drilling a clean hole and putting a strap around the pipe to hold in an

EGT probe?  



Gents with due respect .... method number one is really classy.  It also

requires you to remove and re-install the whole exhaust system, take the

chance of the guy screwing up the weld and really making a mess of your

exhaust in the process, and this is being done because ..... 



Drilling a hole is not classy?  And if you drill it poorly it MIGHT

crack?  In which case you would weld the crack?  



Sorry.... um... hand me the drill.  



Mark Bitterlich and JUST my 2 cents here.  



P.S.  I have seen the welded bungs for a smoke system crack ALL the time

in Sukhoi aircraft.  On the contrary, I have also seen the smoke system

that just drills a hole and puts in an injection nozzle held in place

with a stainless hose clamp.  Method number two can be easily repaired

and lasts a long time.  Method number one is a real pain in the ass.

Sometimes the simple method is better than the classy method.  



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keithmckinley

Joined: 11 Aug 2008
Posts: 434

Posted: Wed Mar 09, 2011 3:27 pm Post subject: Re: EGT probes

didn't know it was titanium and by the way one can find fault with just about anything if one really tries.

radiopicture

Joined: 23 Jun 2008
Posts: 263

Posted: Wed Mar 09, 2011 7:02 pm Post subject: EGT probes

Yea, and brittle as hell because it's not really an alloy. There are a few stray impurities, but it's almost pure.

On Mar 9, 2011, at 6:27 PM, keithmckinley wrote:



 	  Quote: 	
		   

 

 didn't know it was titanium..

 

 --------

 Keith McKinley

 700HS

 KFIT

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=333387#333387

keithmckinley

Joined: 11 Aug 2008
Posts: 434

Posted: Wed Mar 09, 2011 9:25 pm Post subject: Re: EGT probes

those things sound pretty expensive...

aerostar6

Joined: 26 Jun 2008
Posts: 33
Location: Amersham, UK

Posted: Thu Mar 10, 2011 1:15 am Post subject: Re: EGT probes

FWIW, my experience. Had two threaded bosses welded into my YAK 50 exhausts for smoke injectors. Very nice and pretty, but the stacks both had to come off within three years for re-weld due to cracking. As I remember it, this was a specialist job, as the weld had to be done in an argon(if my memory correct) atmosphere.



That said, I switched from flexible to rigid lines where the pipes meet the injector, and haven't had a problem since, and that was 8 years ago.. My buddy has, on the other hand, had the simple hole/strap arrangement on his '50 for the same time with no problems at all.

radiopicture

Joined: 23 Jun 2008
Posts: 263

Posted: Thu Mar 10, 2011 6:10 am Post subject: EGT probes

We've done the Sukhoi exhaust stacks (both sides that include the terminus) several times. The flange that accepts the smoke injectors do crack, and the correct welding rod and technique takes some research and some trial and error, even for the best welders. Also, you're correct, the hose for the smoke oil needs to be flexible (to slow down cracking), and it matters where it's fastened, etc. To be airshow ready, Rick felt it necessary to have a pair of spare stacks repaired and on hand (they're scarce as hen's teeth). It's a matter of slowing down the cracking, not stopping it (in this case).



Just due to reduced mass and the fact that the thing isn't welded on with all of the accompanying problems, I think the simple hole is better, as Mark pointed out. Of course, that's not an option with the smoke nozzles, and I also realize there are other applications where the threaded flanges might work better for EGT probes. 



Really, I'm talking about the SU-26M and thinking Yaks are probably similar in this respect.

On Mar 10, 2011, at 4:15 AM, aerostar6 wrote:



 	  Quote: 	
		   

 

 FWIW, my experience. Had two threaded bosses welded into my YAK 50 exhausts for smoke injectors. Very nice and pretty, but the stacks both had to come off within three years for re-weld due to cracking. As I remember it, this was a specialist job, as the weld had to be done in an argon(if my memory correct) atmosphere.

 

 That said, I switched from flexible to rigid lines where the pipes meet the injector, and haven't had a problem since, and that was 8 years ago.. My buddy has, on the other hand, had the simple hole/strap arrangement on his '50 for the same time with no problems at all.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=333431#333431

dabear(at)devere.us
Guest

Posted: Thu Mar 10, 2011 6:23 am Post subject: EGT probes

I put nine probes on the EGT side to monitor instant changes of the

cylinders and then 5 on the CHT side monitoring the first 5 Cyl.  That gave

me plenty of measurements.  Now I've heard of some folks putting switches in

between the sensors and the Dynon to switch between sets of sensors and get

all 18 but I don't think it is needed.



I'm enjoying the heck out of the SV system.  I think you'll like it once it

is installed and de-bugged.



Bear



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