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912 Exhaust Temp Question

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ricklach

Joined: 20 Jun 2006
Posts: 127
Location: Kernville, Calif.

Posted: Sat Oct 30, 2010 8:17 am Post subject: 912 Exhaust Temp Question

After installing a new Grand Rapids EIS 2000 to monitor my Rotax 912S engine, I now have a lot more information to worry about. The first thing that Iâ€™m not to sure about is the EGT readings. Itâ€™s showing 1550 to 1680 all the time. The sensors are about three inches from the cylinder heads per the installation instructions. The other important thing, the exhaust pipes are wrapped to the muffler with Exhaust Insulating Wrap. I sure this increases the temperature in the pipe, but by how much? What are you guys with digital EGT set-ups seeing for temps? Can you give me any comparison temperatures, to give me an idea as to what I should be seeing.  One more thing, Iâ€™m running premium auto gas.

_________________
701Driver
N35 26.700, W118 16.743

ollie6a(at)embarqmail.com
Guest

Posted: Sat Oct 30, 2010 10:31 am Post subject: 912 Exhaust Temp Question

My temps with EIS run about 1550* I run both 100 and auto and don't

see any difference.



On Sat, Oct 30, 2010 at 12:17 PM, ricklach <rick(at)ravenaviation.us> wrote:

 	  Quote: 	
		   



 After installing a new Grand Rapids EIS 2000 to monitor my Rotax 912S engine, I now have a lot more information to worry about. The first thing that I’m not to sure about is the EGT readings. It’s showing 1550 to 1680 all the time



 --------

 701Driver

 N35 26.700,  W118 16.743





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=317497#317497




	


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 	  Quote: 	
		  From Central Florida,

 Ollie

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sat Oct 30, 2010 1:28 pm Post subject: Re: 912 Exhaust Temp Question

If you use exhaust header wrap you absolutely can't have the wrap touching the sender on the top, underneath or the sides. I did a research project on this with Dynon units and found that what ever the composition of the wrap is it interferes with the milli volt signal in the sender. I talked to Rotax and Dynon and no one had any explanation. It happened to me and as soon as I moved the wrap away from the sender my temps were not swinging and fell back about 80-100 degrees. Normal EGT temps depending on the OAT and if you have a cowl and or a tight cowl may be between 1350F-1480F. This is some of the problem with the new digital EMS's is that they give a lot of info, but you need to know how to interpret that info or you may lead yourself down the wrong path and if nothing else go insane. Many people don't have a digital EMS so they never see any of this data and most likely live a more stress free life, so don't get to over wrought with trying to make numbers always be like some one else's or make them perfect. There is no such thing. Look at the Rotax manual and so long as the numbers are between the lows and highs you are probably just fine. There will be a difference in your many numbers between seasons, too.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

dirtfly7(at)yahoo.com
Guest

Posted: Sat Oct 30, 2010 9:30 pm Post subject: 912 Exhaust Temp Question

Why is everyone worrying about EGT when you can't do anything about it anyway, There is no mixture control.  Get rid of the EGT gauge and save yourself some stress.

Joel



--- On Sat, 10/30/10, Roger Lee <ssadiver1(at)yahoo.com> wrote:

[quote]

From: Roger Lee <ssadiver1(at)yahoo.com>

Subject: Re: 912 Exhaust Temp Question

To: rotaxengines-list(at)matronics.com

Date: Saturday, October 30, 2010, 3:28 PM



--> RotaxEngines-List message posted by: "Roger Lee" <[url=/mc/compose?to=ssadiver1(at)yahoo.com]ssadiver1(at)yahoo.com[/url]>



If you use exhaust header wrap you absolutely can't have the wrap touching the sender on the top,  underneath or the sides. I did a research project on this with Dynon units and found that what ever the composition of the wrap is it interferes with the milli volt signal in the sender. I talked to Rotax and Dynon and no one had any explanation. It happened to me and as soon as I moved the wrap away from the sender my temps were not swinging and fell back about 80-100 degrees. Normal EGT temps depending on the OAT and if you have a cowl and or a tight cowl may be between 1350F-1480F. This is some of the problem with the new digital EMS's is that they give a lot of info, but you need to know how to interpret that info or you may lead yourself down the wrong path and if nothing else go insane. Many people don't have a digital EMS so they never see any of this data and most likely live a more stress free life, so don't get to over wrought with trying to make numbers always be like!

  some one else's or make them perfect. There is no such thing.  Look at the Rotax manual and so long as the numbers are between the lows and highs you are probably just fine. There will be a difference in your many numbers between seasons, too.



--------

Roger Lee

Tucson, Az.

Light Sport Repairman - Maintenance Rated

Rotax Repair Center

Home 520-574-1080  TRY HOME FIRST

Cell 520349-7056





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Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sun Oct 31, 2010 5:03 am Post subject: Re: 912 Exhaust Temp Question

Knowing what the EGTs are doing during flight can lead to early detection of a carb or intake problem. 



My installation manual says 

"nominal approx. 800C (1470F)

max. 850C (1560F)

max. 880C (1616F at take off 

(readings of EFT taken approx. 100mm(3.93 in)from exhaust flange connections)."

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

ricklach

Joined: 20 Jun 2006
Posts: 127
Location: Kernville, Calif.

Posted: Sun Oct 31, 2010 6:29 am Post subject: Re: 912 Exhaust Temp Question

Joel I can not agree with you. Iâ€™ve spent my life building engines and hundreds of hours on a Dyno and you can change the exh-temps. Timing and carb mixture are just two that can make a nice tuning difference in that area. On the other hand the engine has 300-hours on it and it hasnâ€™t melted yet. But 1600 degrees or higher is not right.



So, Roger, the exh-pipes were wrapped before I installed the temp probes. I just drilled through the wrap and pipe, slipped in the prob along with some high-temp silicon to form a seal and tightened then down with the hose clamp then come with. If I under stand you correctly I should remove them, enlarge the hole in the wrap so the probe can not touch the wrap and then reinstall them again. Two questions:



1.	Dose it matter that the clamp will be touching both the wrap and the probe?  

2.	I used red high-temp silicon to seal around the probe, do you think this could be making a difference?



Thom, thanks for your numbers, appreciate more numbers if you guys have them. 



Rick

_________________
701Driver
N35 26.700, W118 16.743

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun Oct 31, 2010 7:06 am Post subject: Re: 912 Exhaust Temp Question

Hi Rick,  (Hope this helps)



I sort of agree that many 912 users don't have digital EGT temp displays and many don't have any EGT gauges and they fly and have never had an issue since 1990. My sort of comment comes because I'm the analytical type and like info, but unless you use the info you get in the correct manner it can be frustrating at the least and cause you to damage your engine at the worst. If the engine is maintained as per Rotax maint. and you don't mess with it it should never have an EGT temp issue as the carbs and things are set from the factory. Remember we don't care about an exact temp, but so long as it is within a range which varies from the winter to summer months anyway. It also will vary with your airport elevation and flying altitude. It will vary depending if you have a cowl or not. It will vary depending on prop pitch and vary depending on the rpm you cruise at. Midrange at 4700 will run hotter than 5100 rpm. Like I was saying above, once you get all this info how do we interpret it. Yes seeing a temp doing something that it shouldn't is worrisome, but you should use it only as a single tool and correlate it with all the other info and engine running to make it make sense or to see if the temp is lying to you or is real. 

When I first put header wrap on my plane the EGT's went crazy and were not only high, but would swing as much as 100F in a few seconds. So that's when I started my little research project. Rick I would advise that you wrap the 2" between the exhaust port and probe and use one clamp for that single piece. Then start the wrap again on the other side of the probe. Use 2" wide wrap and only over wrap each wind by about 3/8" and no more or it will retain too much heat. The wrap should be slightly moistened when you apply it. I wrap all the way down to the muffler and under the springs then put a clamp under the springs. This will also help if you happen to get a little blow by gas at the knuckle. I wouldn't let the clamps come in contact with the probe. If a single strand of cut wrap touches the probe it doesn't seem to make a difference, but allow much of the wrap to touch or cover it does make a difference. I have had header wrap on my pipes from the exhaust port right down to the top of the muffler now for 3.5 years and have not had a single issue and I know many 912 users that have header wrap just like mine. It does make a difference on the temps inside the cowl. The wrap Mfg. claims up to 70% heat reduction off the pipes. I don't know if it's really that high, but when I land and pull the cowl I can grab my exhaust pipe where as with out the wrap I'd be pulling my skin off. It does help protect the wiring and any coolant or oil lines near by from radiated and convective heat. I don't see any higher EGT temps with or with out the wrap. I have a Dynon D120 EMS. Oh yes I forgot the silicone question. I don't personally know of anyone that uses it. If the hole in the pipe was an exact fit for the probe and you clamp it down it shouldn't be a problem.



I would worry more about odd temps if you are someone that doesn't maintain your engine or likes to experiment and make changes on your Rotax engine different from factory. The way it comes from the factory should be fine for most and should have darn few exceptions.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Sun Oct 31, 2010 7:27 am Post subject: Re: 912 Exhaust Temp Question

 	  Thom Riddle wrote: 	
		  Knowing what the EGTs are doing during flight can lead to early detection of a carb or intake problem. 



My installation manual says 

"nominal approx. 800C (1470F)

max. 850C (1560F)

max. 880C (1616F at take off 

(readings of EFT taken approx. 100mm(3.93 in)from exhaust flange connections)." 	




They can be good debugging tools also. I.e. right after I got my current plane one of the carbs got plugged up due to a failed fuel line replacement job by yours truly. Basically one side of the engine would starve of gas and shut down as I approached full throttle. 



Back at the ramp I could see which side was affected, the EGTs plummeted on that cyl. bank as I opened it up and it do it's stumbling thing. 



Another installation problem the plane initially had was the carby vent lines not being put at the same atmospheric pressure as the intakes. I.e. they were just run alongside the carbs on the outside. The EGT showed me the effects of that, basically too cool at full power - 1100 to 1200F. Once I routed them into the back of my airfilters I was able to see them get back up into a more normal range, about 100F hotter (for my altitude anyway, the carbs seem to run a hair rich at full power at my altitudes of 7000' MSL and above and the dangling vent lines really show up as rich running up here).



They were useful for setting my idle mixture too. Like I said, I live at a high altitude so the factory idle mixture of 1.5 turns on the screw is way too rich. At first I didn't realize that 800 to 900F at idle was a symptom, until I kept noticing my plugs getting fuel fouled at idle. But the EGT's helped me to find the "peak" when I was setting my idle mixture so I could finally get it set right (seems to idle best slightly rich of the peak idle EGT of about 1100F)



Like Roger says, you have to be able to interpret the info they're giving you or you will end up in the rubber room if you concentrate on them too much.  But I still think they're worth installing if for no other reason than finding problems. 



LS

_________________
LS
Titan II SS

daveaustin2(at)primus.ca
Guest

Posted: Sun Oct 31, 2010 3:06 pm Post subject: 912 Exhaust Temp Question

Re the exhaust wrap, to change the subject just a bit..

My understanding is that the higher the stainless steel is heated, the faster it will harden and 

start the inevitable cracking process.

So why do you wrap ss exhaust pipes?

Dave  601HDS 912UL

dirtfly7(at)yahoo.com
Guest

Posted: Sun Oct 31, 2010 3:39 pm Post subject: 912 Exhaust Temp Question

Everyone has the freedom to do what ever they want and thats just fine.  I have over 2000 hours behind the 912uls and never had a EGT gauge.  If you leave everything alone and keep it the way it was setup at the factory it will last along time.  Keep your oil temps and CHT in range and it takes care of itself.  If you keep the carbs in sync and do your regular maintenance and don't try to fix what isn't broken you will have a trouble free running engine.

Joel



--- On Sun, 10/31/10, ricklach <rick(at)ravenaviation.us> wrote:

[quote]

From: ricklach <rick(at)ravenaviation.us>

Subject: Re: 912 Exhaust Temp Question

To: rotaxengines-list(at)matronics.com

Date: Sunday, October 31, 2010, 8:29  AM



--> RotaxEngines-List message posted by: "ricklach" <[url=/mc/compose?to=rick(at)ravenaviation.us]rick(at)ravenaviation.us[/url]>



Joel I can not agree with you. IÃ¢â‚¬â„¢ve spent my life building engines and hundreds of hours on a Dyno and you can change the exh-temps. Timing and carb mixture are just two that can make a nice tuning difference in that area. On the other hand the engine has 300-hours on it and it hasnÃ¢â‚¬â„¢t melted yet. But 1600 degrees or higher is not right.



So, Roger, the exh-pipes were wrapped before I installed the temp probes. I just drilled through the wrap and pipe, slipped in the prob along with some high-temp silicon to form a seal and tightened then down with the hose clamp then come with. If I under stand you correctly I should remove them, enlarge the hole in the wrap so the probe can not touch the wrap and then reinstall them  again. Two questions:



1.    Dose it matter that the clamp will be touching both the wrap and the probe?  

2.    I used red high-temp silicon to seal around the probe, do you think this could be making a difference?



Thom, thanks for your numbers, appreciate more numbers if you guys have them. 



Rick



--------

701Driver

N35 26.700,  W118 16.743





Read this topic online here:



http://forums.matronics.com/viewto;  --> http://www.matronics.com/Navigator?RotaxEngines;            - MATRONICS WEB FORUMS - [quote][b]

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Sun Oct 31, 2010 4:37 pm Post subject: 912 Exhaust Temp Question

Joel, all, One thing an EGT gauge will tell you is if you get an air leak in the carb boot. There was a batch of bad boots made in the mid oughts that were pretty much failed as they left the factory and started to crack through long before normal expectations of the 200 hour check. To make a long story short, rising EGT's alerted me to something amiss and I found the cracks before I had engine damage.  Whether E-AB or E-LSA, they are all individual experiments and should be conducted accordingly. I believe an EGT is cheap insurance, but that's my decision.

Rick Girard



 On Sun, Oct 31, 2010 at 6:35 PM, Joel M. <dirtfly7(at)yahoo.com (dirtfly7(at)yahoo.com)> wrote:

 	  Quote: 	
		   Everyone has the freedom to do what ever they want and thats just fine.  I have over 2000 hours behind the 912uls and never had a EGT gauge.  If you leave everything alone and keep it the way it was setup at the factory it will last along time.  Keep your oil temps and CHT in range and it takes care of itself.  If you keep the carbs in sync and do your regular maintenance and don't try to fix what isn't broken you will have a trouble free running engine.

 Joel



--- On Sun, 10/31/10, ricklach <rick(at)ravenaviation.us (rick(at)ravenaviation.us)> wrote:

 	  Quote: 	
		   

From: ricklach <rick(at)ravenaviation.us (rick(at)ravenaviation.us)>

Subject: Re: 912 Exhaust Temp Question

To: rotaxengines-list(at)matronics.com (rotaxengines-list(at)matronics.com)

 Date: Sunday, October 31, 2010, 8:29  AM



--> RotaxEngines-List message posted by: "ricklach" <rick(at)ravenaviation.us>



Joel I can not agree with you. Iâ€™ve spent my life building engines and hundreds of hours on a Dyno and you can change the exh-temps. Timing and carb mixture are just two that can make a nice tuning difference in that area. On the other hand the engine has 300-hours on it and it hasnâ€™t melted yet. But 1600 degrees or higher is not right.

 

So, Roger, the exh-pipes were wrapped before I installed the temp probes. I just drilled through the wrap and pipe, slipped in the prob along with some high-temp silicon to form a seal and tightened then down with the hose clamp then come with. If I under stand you correctly I should remove them, enlarge the hole in the wrap so the probe can not touch the wrap and then reinstall them  again. Two questions:



1.    Dose it matter that the clamp will be touching both the wrap and the probe?  

2.    I used red high-temp silicon to seal around the probe, do you think this could be making a difference?

 

Thom, thanks for your numbers, appreciate more numbers if you guys have them. 



Rick



--------

701Driver

N35 26.700,  W118 16.743





Read this topic online here:



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ricklach

Joined: 20 Jun 2006
Posts: 127
Location: Kernville, Calif.

Posted: Mon Nov 01, 2010 6:42 am Post subject: Re: 912 Exhaust Temp Question

Dave,



I put exh-wrap on my 701 to lower the temperatures inside the cowl. I live in the Southern California Mountains and every time I go anywhere I'm in the desert, where 100 degree days are common. The wrap lowered the Oil-temp, water-temp and cylinder heat temp significantly. Everything was on the high side during summer and now they are perfect. Like Roger said. After a flight you can pull the cowl and it's worm in there but not cooking like it was.



Rick

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N35 26.700, W118 16.743

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