The Savvy Aviator #59: EGT, CHT and Leaning - AVweb

Mike -
I appreciate this opportunity to ask you an educated question…
I also have taken the APS course in Ada, Ok and have owned my Pa24-260 Comanche GTO since 2001, presently equipped with JPI830, GAMI injectors, and EIS ignition.

So, here is the dilemma I have. I recently determined by collected data that my “best” speed altitude at 75% Power is 9600 Density Altitude, at very close to Peak EGT (to slightly less, about 10 deg LOP) is 174 KTAS… all with CHT’s at or below 380.

This seems to go against the RED-BOX grain Mantra, operating at 75% Power (13 gph in 260 HP IO540).

  1. Even though my safe-target-CHT-380 is always met, is this potentially unsafe/unhealthy for the engine to operate at Peak EGT with 75% power?

  2. Naturally, operating at 50 deg LOP is CHT-cooler (and slower), but for best speed, and avoiding ROP, what is your opinion regarding operating at Peak EGT at 75% Power, yet with cool CHT’s?

Thanks in advance for your wisdom.

Tom Wolf
N8684P - Comanche 260 LoPresti GTO