| of inconel sheathed probes and someone was asking not too long ago where I got them from - can't remember who it was. In late 2003 just before my move to the GA land I was in my Z and boosting her pretty good when I started having misfire and hearing some awful noises coming from the driver's side turbo. These were new ball bearing turbos that only had about 5000 miles on them at the time and I knew something was bad wrong. I didn't risk driving the car anymore and had it shipped to GA. When I pulled it apart I found that the Westberg EGT probe on the driver's side had disintegrated to pieces which destroyed the turbine of the turbocharger. Additionally, since there is a degree of exhaust-reversion that occurs during valve overlap, some of these little pieces found their way into the combustion chambers and this was evident by a large number of small pits on each piston crown and combustion chamber, with progressively less of this as you moved towards to two other cylinders further towards the front of the engine. But there was enough exhaust reversion occuring to blow the pieces all the way to cylinder #2 at the front of the engine. This is another reason why our torque curves fall off so sharply too, but that's another topic alltogether. This resulted in a complete rebuild of the engine and was the main reason my car was down for so long late 2003 and why my Z didn't make it to NOPI 2003. I took the time thereafter to design the Stage2 turbo and was waiting for their arrival the day before NOPI. :-/ Anyway, to my point... I cannot find the probe that destructed, but I have the probe from the passenger side which was already showing signs that it was about to fail. During the rebuild I looked for another EGT probe solution as I wasn't about to risk another engine and turbos over an $80 set of probes. I searched and found a company called Grand Rapids Technologies which advertised an EGT probe that uses an inconel sheath. Now we all know why Greg chose inconel for his exhaust manifolds - they aren't as susceptible to failure due to the intense heat of being an exhaust component. I was sold, not to mention, they were only $33 each! Save $7 a piece for a better product! The westberg EGT probe is what they call a "wire in a tube" design. It is simply a stainless steel tube (304 SS) with the bimetal (chromel and alumel) thermocouple packed in with a ceramic insulator. The tip of this tube is 'rounded' off to close the end up, but a very small amount of the ceramic sticks out of the end. Since stainless steel has such a high thermal expansion rate as compared to other metals, when this tube heats up, it expands, and it expands a LOT. The inconel sheathed probe uses a small inconel tube which is manufactured with a closed end. It is analogous to a test-tube. The bimetal thermocouple is inserted and held in place with ceramic. Here are some picture comparisons of the two thermocouples: In this picture you can see the Westberg probe on the left and the GrandRapids on the right.
 
If you look closely at the tip of the probe you can see the differences I am talking about. You can even see that the westberg probe is already coming apart at the tip and some of the ceramic has already broken out of the tube. These particles being thrown into a turbine that is spinning at 140,000RPM are like sniper-rifle bullets when they impact. The probe that I cannot find which resulted in the destruction of the driver's side turbo was actually missing the entire end that was in the path of the exhaust. Both of the probes were inserted about 3/8" into the gasflow and the heat was just too much for them to take. They are not suitable for a turbocharged application. In fact, the westberg probe in the picture is stuck within the bung that is used to mount it into the manifold due to the thermal expansion and distortion it experienced. The GrandRapid probe you see here was removed from the my jet engine exhaust piping which runs between the turbine and the afterburner. It has experienced temperatures well over 2000 degrees in a few events where a turbine burned up due to a combustor flame-out and it slid right out of the bung just a few moments ago with very little visible signs of use and no distortion whatsoever. I just checked it with a voltmeter and a lighter - still works properly too. These are the only probes I would recommend anyone to use, but keep in mind this is only the probe, not the gauge. You will need some way of reading the probe's voltage in order to determine the temperature, but these probes are what I use with the ZEM (this is not a ZEM sales pitch post) but they are a "K" type thermocouple that can be used with any EGT setup using this standard of probe. If any of you have westberg probes, try removing the probe and you'll see that they are stuck because they have thermally expanded and distorted. Once you remove it by unscrewing the bung, you'll see the same distortion at the tip and perhaps even some missing ceramic too. Just wanted to try and save you guys the hassle, frustration, and a few thousand dollars that I had to go through a while back. All this because I found an old invoice while unpacking a few last things, LOL. BTW, Grand Rapids Technologies website is at [ http://www.grtavionics.com/ ] The part number is EGT-CF-02
Description: EGT Probe - 8mm threaded They have some pretty nice engine monitoring systems for aircraft that can be used with these probes too. FAA approved stuff though - gonna be very pricey for these monitoring systems but the probes are inexpensive.
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Inconel EGT probes. Just found an old invoice for a set - 
09:29:33 12/04/04
