On 03/09/2012 11:22 PM, DLOMHEIM@aol.com wrote:

Tracy wrote:  >As usual, the in-flight symptom was a rise in EGT on the affected rotor.

 

Can someone describe the science behind a "rise in EGT" when we lose a single coil.  I would have expected a drop in EGT due to less thorough burning of the mixture and therefore excess un-burnt fuel which I thought would provide cooler temps of the exhaust stream as it passes the EGT probe.

 

Must be missing something very basic here...

 

Thanks for any clarity!  :)

 

Doug Lomheim

RV-9A / 13B FWF

I think the missing piece is that when running rich of peak to cool the exhaust, the mixture leaves the chamber without any oxygen remaining and with the burn therefore complete.  When a coil dies, there's still some oxygen left, so the mixture is still burning as it enters the exhaust.