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dahugo

Member
Pardon this post if the answer appears elsewhere but I was not able to find the answer searching other threads.

We (meaning me and my other builders) just cranked our IO-320 for the first time in our 9A. And since I am the only pilot of the group (at present) I, of course, must complete the POH.

The Lycoming book on my IO-320 says CHT's should not exceed 435 degrees. However, one of my old sage instructors who is anal about these things said that even though the book list 435, there are those who fret over CHT's in excess of 400.

Of course, the Lycoming book is "gospel" for my engine, but I also know that CHT's with any given engine will be different based on the aircraft in which it is installed, and then any peculiarities of the particular aircraft (such as the baffling.)

So, what I want to know is, with properly fabricated baffles, what sort of CHT's should I expect with my IO-320 on initial climb, cruise climb, cruise, descent, etc? I don't want to list 435 as the red line for CHT's if, in a typical RV-9A installation, most of you guys are getting climb CHT's of 400 or so.

Any information is, of course, greatly appreciated.
 
Depends

My IO320 runs about 390 on hottest cylinder on initial climb on a hot day (2000DA). Level off and it drops to 325 or so. On a cooler day, it goes no more than 375 on climb. Runs a little hotter after I had my fuel servo adjusted to a leaner mid range.
 
Use Lycoming's numbers.

Hugo, you'd do well to list Lycoming's numbers in the POH, for all temps and pressures.

You don't want to list 400 deg and then, next summer, happen to see 405 on a prolonged climbout. If you have a 'glass' panel, program the redline to Lyc's specs....there's already a built-in safety margin.

Best,
 
dahugo said:
The Lycoming book on my IO-320 says CHT's should not exceed 435 degrees.
Click to expand...
Are you sure that it doesn't say Max. CHT 500 deg?

The manual for the O-320 says (expect that the IO-320 is the same):
Never exceed the maximum red line cylinder head temperature limit.
For maximum service life, cylinder head temperatures should be maintained below 435°F
(224°C) during high performance cruise operation and below 400°F (205°C) for economy
cruise powers."

We set the Dynons yellow at 430 and red at 450 max is 500 for the O-320.
 
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Never exseed is 500

Absolute Max is 500 RED

Avoid from 450 on Yellow

Max Power Cruise 435 still in the Green

Normal Cruise 400 Green

Resume: Green 0 to 450
Jellow 450 to 500
RED 500 to 550

So, climbing on a very hot day is OK to see 435

Healthy cruise below 400. Best between 350 and 380 !!!
 
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Here we go, about to start a big fight here. And heck I do not care......I am a long way away :) but lets be real here.

Lycoming set a max CHT which is a book figure, but go do some research on the strength properties of aluminium alloys. Start thinking about this with a bit of scientific thought.

Now I would suggest that your green range be up to 380, Yellow 380 to 420, and red over 420.

Yes before any of you get carried away with "but I live in Texas".......BS, I live in Qld, and I fly around northern Australia, no different.

I never see climb temps above 380-385 and cruise between 295 and 335, maybe 340 on the hotest of days. The IO540 is just a IO-360 x 1.5 so no big difference.

Sure you can "set" you numbers where you like, but trust me, I may just be speaing from a better informed position ;).

If I saw CHT's in the 460+ range I would be really worried :eek:
 
Pierre Smith's background? :)

pierre smith said:
Me too, but that wasn't the original poster's question, now was it?:) It's a full moon and I don't wanna fight either:)

Best,
Click to expand...

Pierre:

You are really speaking our Austrailian friend's language here...you wouldn't by chance also have learned "the Queen's English" in Canada (or elsewhere?) some time ago as a young chap, would you? :)

Fly safe!

Doug Lomheim
RV-9A / Mazda 13B / FWF
 
Zimbabwe, originally.

All my schooling was in Rhodesia, under the British system and I graduated in 1961 and I spelled color as colour and so on. We emigrated and moved to upstate NY, then to California, where I was drafted as an alien, nevertheless, into the US Army, in 1966.

Best,
 
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