Mogas: what happens to EGTs?

-
-1 What is it going to show happened to the EGTs when you switched
-tanks?

The EGT should show a very slight increase. The higher the octane, the smoother
and cooler the burn. You have gone from 100 octane to (arguably) 87 or 93
octane and the car gas should burn hotter.


-
-2 What is it going to show happened to the CHTS when you switched
-tanks?

If the EGT (internal temperature of the cylinders) goes up, the CHT must follow
suit, but at an even reduced value as regards the EGT rise.


-
-3 (not in the JPI, but: ) What is the airspeed going to do? Increase?
-Decrease? Stay the same?

Increase, ever so slightly. The efficiency (and therefore power output) of any
Carnot cycle engine is a function of the temperature difference between intake
and exhaust temperatures. If the intake remains constant (ambient) and the
exhaust rises, the horsepower produced goes up and the airspeed...EVER SO
SLIGHTLY...increases.

Then again, I'm a sparky. What the hell do I know about engines.


Jim



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com