Screaming HIGH EGT's 582

26 posts in this topic

Posted (edited)

Just putting a 582 in Service and am getting some screamin high EGT's, predominantly 4500 to 5500, however the numbers are higher than anticipated across the board.

582 with 2.62 C box and GSC 3 blade turing 6500 at full power at 55 MPH (as a setting). 6,200 static on the ground.

EGT's run 1300-1400 at mid range though do pull down to 1200 at full power.  Still way too high.

All items are new, including carb boots and engine seals.

Needle is in the richest position.  All needles, needle jets, main jets and pilot jets are per Bing spec for the 582.

OAT at 50F.

Any thoughts?  Plugs look good and engine runs fine.  Kinda thinking (and hoping) that it is an indication issue?

Larry

 

 

 

 

Edited by LSaupe

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Posted

I would think indication as well ,plugs are the definitive I believe 

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Posted (edited)

I would have expected the plugs to show lean.  Is it possible the gauge is off?  How does the CHT look when running 1400 EGT for a bit?  With everything else being normal, I might try a new gauge.  I didn't call out the sensors because both of them are supplying the same high reading (both wrong by the same amount).

Edited by Knuckledragger

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Posted

What do you mean per Bing Spec? There's a pretty extensive chart for jetting depending on altitude. What are you running for main jets? What are you using for probes and an EGT gauge? If you were truly at 1400 degrees you'd probably be writing to ask about rebuild options. Not a whole lot you can do for a whacked indication I'd pull the probes out of the manifold and double check all your wiring. If that's all good not sure what else there is to do except get a new set of probes and a quality gauge like a Westach.

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Posted

Bing Spec is referring to the Bing manual baseline call out for the 582 (i.e. how they are originally calibrated, without changes for density altitude)).  Mains are 155 (I think, book is still up at the airport) Gauges are Westac, as supplied by Kitfox.  We are operating at 1,000 ft AGL.  Will be installing a new EGT system in the AM (probes and indicator).  Been doing some digging just now and it appears the GSC prop might be a player here (not the best loading profile over the rpm range, especially if not loaded enough). Others with GSC have seen the same 1300-1400 indications. Underloads the prop too much at less than full power.

EGT's were on the high side with blade angle set at 13.5 degrees.  We dropped it to 12.5 degrees (as recommended by GSC) as the static and climb RPM were a bit low at 13.5 degrees (5,700 and 6,000 respectively). EGT's did go up a bit with that change (now 6200 and 6500 respectively).

We have several 582's flying in our chapter and none are like this, all have the same getting and climb RPM.  None with GSC however.  They are using Warp, Ivo and Powerfin.

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Posted

I would have expected the plugs to show lean.  Is it possible the gauge is off?  How does the CHT look when running 1400 EGT for a bit?  With everything else being normal, I might try a new gauge.  I didn't call out the sensors because both of them are supplying the same high reading.

CHT's seem to stay rather constant, around 250F.

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Posted

Prop pitch plays a huge role in egts. I can't believe how much I can change mine with my Ivo IFA. 

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Posted

Hmm, reading this makes me think I had my GSC set at 13*. Can't be certain without the log though, sorry.

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Posted

Standard main jet for a duel carb 582 should be a 165.  Jim Chuk

PS I'll scan the chart for jetting after Orielly is over

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Posted

Here are the charts from my CPS catalog.  Jim Chuk

Bing jet correction chart 001.jpg

Bing jetting chart 001.jpg

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Posted

Thanks for posting Jim.I know the mains matched the uncorrected chart (shown at 165 here, I was guessing when I posted last night, might have crossed my 65 with a 55 in my mind with the idle jets).  Will verify that though.   Gonna try a new EGT gauge and sender system this AM.  

I had my GSC at 13.5 degrees and things were marginal (low performance and high EGT, just under 1250).  I have it set at 12.5 degrees now and have better performance and crazy EGT's.  I am kinda leading towards the gauge and prop now.  

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Posted (edited)

Should be 165 as Jim said.  Also lower the clip on the needle to the third position from the top and see how that does.  Anything that shows over 1200 on the EGT's is asking for trouble.  I run 2 jets.  165 in the summer and 170 in the winter and with the IVO IFA and the inflight adjustable mixture I can keep the EGTS right where I want them. 

 

If you can take a picture of your plugs and post them that would help us out too.

 

:BC:

Edited by akflyer

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Posted

The spark plugs don't lie.  (hard to read them when you're in the air though) ;-)  I almost hate to tell this story, but it did happen to me.  When I got my first Avid, I noticed they had redlined the EGTs at 1350 or 1400.  I thought to myself, that's kind of goofy.  Had new seals put in the engine and once I started to use it the EGTs did run scary high.  Ran it rich as possible, so much pitch it bogged down the engine on take off, different EGT gauge that had been sent back to Westac for calibrating.  Different props.  Plugs showed black as can be.  That engine was a 532.  Ended up putting in a 582 that I had acquired using the same muffler as before.  That engine ran just like the 532, high EGTs.  When I bought the MK IV, It also had a 582, and I borrowed the muffler from it and put it on the first plane while I was remodeling the MK IV.  Instantly my EGT temps went to were they should have been with the rich carb settings and over pitched prop.  I can't explain this, the EGT probes were where they were supposed to be, and the same exhaust manifold was used.  Both mufflers were from Avid and looked the same.  The reason I said I hated to tell this story is I would hate to have you right away say your problem is the muffler's fault and then find out it wasn't when you cooked the engine.  If nothing else works, maybe you could borrow a muffler from someone just to see if things are different then.  Like I said before, I can't explain why a muffler would make EGT temps higher than they really are.  I still say it can't. (maybe???)   If temps really were 1350 to 1400, I should have cooked the engine.  But I didn't cook the engine and even though I have only one working eye, it's plenty good enough to read an EGT gauge.  A mystery for sure.   Jim Chuk

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Posted

Another not so helpful post but I bot my KF3 from a field elevation of 1200' and flew from a field at 600'. I remember changing needle positions, I assume lower (again, sorry, can't remember to/from clip) but it did make a small difference in EGTs. Seem to have less and less brain space these days and I think I subconsciously deleted most of my 2-strike experience after moving on from my 'learning experience'. :)

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Posted (edited)

Quick update and more confusion I guess.

Tried the TC calibrator on the Westach EGT guage and even though the calibrator was putting out the correct mV it would stop working when connected to the instrument (not sure why yet).  Tried a new instrument out of the box (though 20 years old) and... one side worked and the other was intermittant.  Shut down and put back the old gauge and for some reason everything is now in line again.  EGT's at about 1050-1100 across the range from 4K to 6K.  Gave it a loop around the pattern and it behaved perfectly (no high EGT's).  Inspected of the engine (through the exhaust ports and plug holes)  and everything looks fine (no evidence of excessive EGT for any length of time).  Actually appears to be running on the rich side.

I am hedging my bets right now on instrument error and will order a new EGT system (probes and gauge).  Just odd that it would go off scale high and both needles together when it happened.  The exhaust is also one area that has my interest (great post Jim).  Never know if there was some sort of "visitor" that had taken up residence at some point.  I will do a boro scope on the muffler to see if I see anything.  I have had situations like that with the sleds but would lose high RPM power (though didn't have EGTs on those sleds).

Thanks for all the feedback so far, this has been very valuable.

Larry

 

 

Edited by LSaupe

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Posted

Does your thermocouple wire run all the way from probe to instrument, or is it extended in some fashion?  What you're seeing matches my frustration with the original Westach instrument which led to a change.  If the calibration worked and the readings were repeatable, you could mark the analog gauge and move on.  The problem is you have to be able to trust the readings and the original gauge never got my vote of confidence.

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Posted

If you have Westac gauges, you can send them in and be fixed or recalibrated.  I think they charged me $25 which is way cheaper than a new gauge and should (maybe?) just as good.  Jim Chuk

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Posted

Remember that gauge is only accurate at 70 degree ambient temps, after that you can run the correction error or just use it to show a "trend".  As Jim said, plugs don't lie.  To get the best plug reading warm the engine up on a set of old plugs, shut down, swap to new plugs and fire it up then go to full power for a minute or two.  Shut down very quickly, you don't want to spend time idling it.  Pull the plugs and see what they look like.  This will tell you if the main jet is sized right.  you can do the same for you mid range and just run it up to about 42-4500 rpm then shut down and see what they look like, this will be fully on the mid range circuit. 

 

:BC:

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Posted

Does your thermocouple wire run all the way from probe to instrument, or is it extended in some fashion?  What you're seeing matches my frustration with the original Westach instrument which led to a change.  If the calibration worked and the readings were repeatable, you could mark the analog gauge and move on.  The problem is you have to be able to trust the readings and the original gauge never got my vote of confidence.

The braided portion runs through the firewall then changes to a non braided (black and white) wires to mate up with the instrument.  Does appear to be an OEM set-up.  However, no temperature gradients in this area to cause mischief

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Posted

Can you tell if the black and white wires are type K extension wire, or just plain wire?  It should be color coded yellow/ red (Chromel/ Alumel). Otherwise it creates additional thermocouples at each junction and throws the results off. 

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Posted

Cant really tell for sure (probably just copper or similar).  If not in a temperature gradient (wires isothermal) they can be any type of wire (no Seebeck voltage generated).  shouldn't have any temp gradients where they are located (just under the dash), but you never know.

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Posted

Well, not really.  In one you've got copper/chromel, the other is copper/alumel.  Each has a different Seebeck voltage.  This is the reason extension wire exists.  At the instrument, the terminals should be isothermal and have the errors calibrated out.  

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I hear ya, and it is good practice to run the same materials back to the gauge if you can.  Just trying to highlight if the wires used (any material) are at a singe temp (or same temp at each end) no voltage is generated and you have the same result as the primary wires.  I have seen several commercial systems run plain copper in isothermal areas.

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Posted

I hope you get the new instrument and probes going quickly.  It's great when you can eliminate instrument problems and get onto to the two-stroke tuning proper.

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I hear ya.  Just ordered the MGL TC-1 (complete with probes for EGT and CHT).  Actually spoke with a full time 2-stroke dyno guy today and he swears by the Innovate Air Fuel Wide Band sensor.  I ordered one of these too.  Maybe overkill, but he does swear by it.

http://www.innovatemotorsports.com/products/MTXL.php

 

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