RV-6 EGT Probe Replacement, Subsequent Higher Temp Readings

[rvmills]

Just replaced a bad EGT probe on a Lycon IO-540 on my RV-6 (#3 Cyl). Install appeared to go well, but #3 EGT is reading about 100 degrees hotter than all other cylinders' EGT. For example: 9500' MSL, 20 F OAT (cold day in RNO), 21"/2100 RPM (55% pwr), 10.7 GPH; EGT 3 showed 1440 peak EGT on the VM-1000, when all other cylinders showed 1300-1340. All 6 CHTs were in the 290-330 range (including #3, so they all appeared matched in temp, thus my suspicion of that #3 EGT).

Any thoughts out there on why the delta? Is there a "break-in period" for new probes? Could the probe tip be in too far, or not far enough? Any experience or guidance out there on this would be most appreciated. Thanks!

Bob
RV-6
N600SS
4SD

[flyeyes]

Originally Posted by rvmills

Any thoughts out there on why the delta? Is there a "break-in period" for new probes? Could the probe tip be in too far, or not far enough? Any experience or guidance out there on this would be most appreciated. Thanks!

Bob
RV-6
N600SS
4SD

Absolute values of EGT are pretty much meaningless (at least in normally aspirated engines). What you really need to know is where you are relative to peak EGT.

I've read that temp values for EGT are very sensitive to probe placement. A couple of millimeters in either direction can make a big difference in the absolute number.

Short answer--don't worry about it.

[rvmills]

Thanks James. Good gouge on the theory of relativity (to peak EGT)! Will watch it and compare to CHT, just to make sure I'm not frying anything...but feeling better about it! Thanks again!

Bob

[lrfrey]

Try swaping two of the EGT probes. This will tell you if the 100 deg delta follows the probe or stays with the cylinder. Could just be a slightly less/more sensitive probe.

Larry

[rvmills]

Good call Larry! Will do that on the upcoming oil change. Thanks!!

Bob