zambuka42 wrote:.....My homebase is as 300ft MSL.. and every climbout, about 4minutes in.. at 25MP - 2500RPM - Full rich Mix.. the CHT temps rise above 400 degrees, and if I don't take the rpm down it will rise to 420.....

What's the CHT redline?
I believe the 206 has an IO-520--
I dunno about those but the TCDS for the 470K in my C180
says the redline is 525 using a spark-plug-gasket type probe,
and 460 using a bayonet probe.
So although I would want to keep an eye on it, 420 is well below redline for my engine.

@StampCreek - Thank you so much for that.. it's what I always did back when I was flying in East Africa, but the pilot who gave me my "changeover" for this gig, told me to pull to 25MP. I'll give full open a shot for my initial climb

@hotrod180 - I'll have to go thru the device's setup.. from the looks of the redline distance.. it's between 450-500.. but I'll need to see what it has been preset for. I'm definitely not hitting redline.. the bar graphs turn yellow when it gets above 410 degrees.. I was just curious if this yellow range was acceptable for this motor during a climb (the stock cht does not have a 'yellow range'.) Thanks for the info!

They used to do a seminar where they'd have something like an IO-540 on a test stand, all instrumented up. They'd "takeoff" then pull the power to 25 square for climb and the motor would immediately start detonating. Not enough to feel in a plane but it showed on the instrumented test. Very cool.

Not sure about a yellow arc on CHT. Just hit the limitations section and see what the numbers are. Sounds user defined. Best of luck!

From the IO-520 TCDS:

NOTE 1. Maximum permissible temperature: Cylinder head bayonet thermocouple 460° F.
Cylinder barrel 310° F.
Oil inlet 240° F.

Looks to be applicable to all IO-520 models.

http://rgl.faa.gov/Regulatory_and_Guida ... v%2026.pdf

Great discussion guys.
I fly my 185 LOP in cruise and wind up at 12.6-13.2GPH with 160MPH/TAS at 7500.
On TO I am starting to use the recommended max continuous power to level off no reduction to 25"/2550 which on the IO-520 is full throttle/2700. Pick a cylinder and monitor the egt and keep that egt the same during the climb by leaning. The FF is higher than the 25"/2550 but the climb to cruise altitude is shorter and it runs cooler.
I had the pleasure of talking to a tech rep from Continental at Sun N Fun this year at some length. His thoughts agreed with the LOP cruise and also the climb power setting I was using. He also reiterated the actual EGT temp is not important, just the difference from peak and keep cylinder temps below 380.
A tip I learned about leaning to LOP at cruise really simplified things. I have a EDM 700 and the 450 FF gauge. The 700 has a LOP feature but is far too time consuming to use. After a few flights you will know about what the FF is at cruise. After level off I give it a few minutes to stabilize then bring the FF back about .8gph or so below the normal cruise LOP value then hit the lean find button and start enriching till the first jug peaks. At this point I will normally run it 20-25 deg below this value depending on what % of power I am running.
Here is a copy of the recommended delta temp to run.

At 65% power, use richer than 100 ROP, or leaner than peak EGT.
At 70%, use richer than 125ºF ROP, or leaner than 25ºF LOP.
At 75%, use richer than 180ºF ROP, or leaner than 40ºF LOP.
At 80%, use richer than 200ºF ROP, or leaner than 60ºF LOP."

Please note that for those that run ROP that the long used and earlier recommended 50-75deg ROP is really too lean for good cylinder longevity.

Tom

Tom

I agree with your process of using a known FF then enrichen to peak as a quicker way to find it.. but i probably wasn't using the same numbers you were. I'll experiment a bit more with what you've shown me. Thank you