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EGT question for the experts?

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13 minutes ago, procharger said:

Mine runs a little over 1500 in the winter when air is dry and cold and

1480 in summer.

Are your exhaust pipes wrapped?

I am wondering if that makes a difference at all.

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I’m always entertained when I descend powered back and the EGT temps rise! Then I remember too much information can spoil a fun flight! 

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Can i re ask my question though ..... if say you have CHT in the RED  and EGT is showing normal...(same cylinder)   can one assume the CHT might be a faulty reading or does cht and egt readings have no correlation at all to each other.     I will also add then in reverse,   if EGT is in the RED,  and CHT is normal can we assume a possible faulty egt reading.   

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By the way I’m stripping all the exhaust wrap off the pipes. I appreciate cleaner uncomplicated systems especially if not need! 

And then one over wraps and makes things worse! 🤔

In Phoenix in July probably needed! 

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Header wrap doesn't affect your EGT reading. because the probe should be 100mm (3.9") out from the exhaust port (many aren't) the fire and heat coming out of there is fairly instant and consistent, header wrap has little to no influence at this stage. Header wrap was originally used by racers to keep the exhaust hot all the way down and out the exhaust pipes. This helped reduced colder gases from creating some back pressure. These guys did this to squeak out a couple more horsepower. For us our pipes are so short it isn't that kind of a benefit. We use it to keep all the hot radiated and convected heat off our hoses and wire insulation. You can test this theory yourself. Tester beware of the first test. Without header wrap would you run your engine and then grab your bare exhaust pipe. If you're this dumb please post the after test pictures of your hand. The second test is with header wrap in place repeat the test. You can not only touch the pipes, but gently grab them and within seconds can hold them.. A greatly reduced radiated heat affect.

 

Because of the material the header wrap is made of and the millivolt use within the EGT over wrapping the EGT probe with the header wrap will cause EGT fluctuations as high as 120F. leaving a 1/4" space on each side is best.

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CHT's are only on cylinder 2 & 3 and most of our EGT's are on the back cylinders 3 & 4. There are a few with all 4 EGT's, but not many. The EGT is a measure of the burn conditions within the cylinder and the CHT the cooling around the head (or the system itself).

So this limits the question to cylinder #3. The answer is yes they can be different. From a loose CHT probe and bad EGT probe or a coolant issue. A reduced flow or using waterless coolant.

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The first flight for my new toy had both CHT reading perfect, slightly bigger mag drop on one side, and slightly higher EGT on one side.

On climb out both CHT perfect,  one EGT went into the yellow and no better at lower power. Landed and checked plugs found one plug blackish and the others all good.

The local Rotax agent  provided a new set of plugs and EGT problem fixed. I believe the high EGT was caused by incomplete combustion in the cylinder causing burning still in

the exhaust port. 

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