CHT recommendations

[Dude]

I had an odd thought while flying yesterday.

Traditionally, we have had CHT info on one cylinder. Now, many planes have
monitors that tell us all 4 or 6 cylinders.

I have been trying to keep all my cylinders under 400 as I believe most of
us are doing. However, I had a thought about that number. Is that a number
that is best for all cylinders, or was it a number that had a buffer built
in because you never new what the other cylinders were really doing?

IOW are we now running too conservatively? My number 2 cylinder wants to
run up to 405 or 410 when the rest are at 385 (75 ROP, 1425 EGT). I have
done EVERYTHING except take out the jug to figure this out. One AP noted
that I would never have been aware of this without the engine monitor and
queried whether we were possibly being too worried about it.

[Bill J]

Same thing here, Cylinder 3 always cruises just about 400 but hits over
that in climbs. Others are about 60F lower. Lycoming factory guy said
don't worry about it. I tried baffleing and no change.

Dude wrote:
> I had an odd thought while flying yesterday.
>
> Traditionally, we have had CHT info on one cylinder. Now, many planes have
> monitors that tell us all 4 or 6 cylinders.
>
> I have been trying to keep all my cylinders under 400 as I believe most of
> us are doing. However, I had a thought about that number. Is that a number
> that is best for all cylinders, or was it a number that had a buffer built
> in because you never new what the other cylinders were really doing?
>
> IOW are we now running too conservatively? My number 2 cylinder wants to
> run up to 405 or 410 when the rest are at 385 (75 ROP, 1425 EGT). I have
> done EVERYTHING except take out the jug to figure this out. One AP noted
> that I would never have been aware of this without the engine monitor and
> queried whether we were possibly being too worried about it.
>
>
>

[C]

On Fri, 24 Dec 2004 15:40:02 GMT, "Dude" > wrote:

>I had an odd thought while flying yesterday.
>
>Traditionally, we have had CHT info on one cylinder. Now, many planes have
>monitors that tell us all 4 or 6 cylinders.
>
>I have been trying to keep all my cylinders under 400 as I believe most of
>us are doing. However, I had a thought about that number. Is that a number
>that is best for all cylinders, or was it a number that had a buffer built
>in because you never new what the other cylinders were really doing?
>
>IOW are we now running too conservatively? My number 2 cylinder wants to
>run up to 405 or 410 when the rest are at 385 (75 ROP, 1425 EGT). I have
>done EVERYTHING except take out the jug to figure this out. One AP noted
>that I would never have been aware of this without the engine monitor and
>queried whether we were possibly being too worried about it.

Just a thought -- have you looked at air flow patterns inside your
cowl and how they cool each cylinder??? You may be getting less
airflow around that cylinder than the others. Or some of the fins may
be gummied up, keeping that cylinder from cooling as efficiently as
the others.

I've found that air flows and cooling can be a very difficult problem
to pin down.


Chuck

[Aaron Coolidge]

Dude > wrote:
: IOW are we now running too conservatively? My number 2 cylinder wants to
: run up to 405 or 410 when the rest are at 385 (75 ROP, 1425 EGT). I have
: done EVERYTHING except take out the jug to figure this out. One AP noted

Does this cylinder have a sparkplug washer CHT probe? These indicate 30 to
50 deg hotter than the well-type CHT probes with the same actual cyl temp.
If this engine monitor is an add-on (even a factory add-on) it may have a
washer CHT probe. The tip-off would be a single-point CHT gauge in addition
to the engine monitor.
--
Aaron C.