Originally Posted by
Lead Balloon
Good news, tio540, your images have been released by the PPRuNe gods.
I’m pleased to say that my guess was correct. The images are of the EGT/CHT plots in many EDM manuals.
To the extent that those plots show that EGT and CHT ‘track’ each other always, they are bull****.
CHT ‘tracks’ EGT while mixture is being leaned from rich of peak towards peak. Then something interesting and counter-intuitive happens, approaching and passing peak EGT. From around 25C rich of peak, CHT peaks then starts to decrease as mixture is leaned further. As a consequence, the CHT at peak EGT is lower than CHT is around 25C rich of peak.
As I noted in earlier posts, this outcome is, despite the plots in EDM’s manuals and ironically, observed on every EDM (and other engine monitor) that takes measurements on real engines in the real world.
Okay, with my limited experience, I only recall one POH specifiying 25 degrees C ROP, all the rest varied between 50 deg C to 125 deg C ROP. So you disagree with EDM, and many manufacturers avoid the 25 deg C ROP. Then you agree with the manufacturers, mostly anyway.