Prop loading

[Allen Sutphin 705]

Seems I have forgotten a lot of stuff lately. Can someone refresh my memory on prop loading/EGT's. If I remember not enough loading causes higher EGT and low CHT where as too much loading causes low EGT and higher CHT. Did have a couple articles on it but misplaced them also. I know that proper loading by static RPM usually keeps everything in check all else being correct. Anybody point me to the article again? A little learning curve on Delorto carbs vs. Bing.

[lostman 198]

I know that more pitch and loading will cool the egts, not sure about how it affects cht temps. I have a 503 in a plane and one degree of change on my blade (not pitch) took me from 1200+ to 1080 ish. Made all the difference I needed. Got lucky to get it perfect with one change,  

[Allen Sutphin 705]

I dug into my  deep dark recesses of my brain and remembered it all.  Underloaded prop gives low CHT and high EGT.  Overloaded prop gives high CHT and low EGT. Providing all else is correct. Generally if static RPM is set correctly, temps fall in line if carbs are set properly and everything is in good shape.

[Avidventurous 22]

Allen.

Jump to about 18:30 in this really good webinar. Of course, after a couple minutes you'll realize you want to watch the whole thing... LOL

[Allen Sutphin 705]

Seen it a few years ago, thanks. I have a decent notebook of problem solver tips that I have acquired over the years. Just have to go thru it and find what I am looking for.  Its cataloged about like a soup sandwich. Just takes a little while to find what I am looking for.

Edited 31 Dec 2019 by Allen Sutphin

[nlappos 413]

Allen, don't worry too much about CHT, the EGT will cook your engine in seconds. Basically, when trimmed at high speed cruise at high EGT (for gas efficiency) do not dive the airplane, this will make the rpm rise and the EGT will go very high very fast. In 10 seconds you can lunch your engine. To descend from high speed cruise, slow down first, then pull back the throttle.

[Allen Sutphin 705]

Back to the unloaded prop theory which is what one is doing in a high speed dive. In an aircooled engine, CHT's are also important especially in an enclosed cowl. Water cooled not so much if cooling system is working properly.