REFLECTOR: CHT's

[Scott Derrick]

Flew this morning after plugging holes in the TCM/Cessna supplied
"between cylinder baffles".  I should have made my own, because the
stock baffles have huge holes in them.  They also don't wrap up around
the sides of the cylinders for optimal cooling flow. I may try to
tighten things up a bit more but it will require me to remove all the
injection plumbing, spark plug wiring and some other stuff.. 

Also adjusted the fuel map and smoothed out a few bumps in the oil
cooler exit duct.

The CHT's are really coming into a comfortable range.  Cruising at 165
KTAS(low power setting) they all stay below 360, but increasing power 
to above 200 KTAS and  #2  climbed to 395, #1was about 365, the rest
were all below 330.  I'm mostly concerned with #2 but would like to see
#1 more inline with the other 4 as well.

I'm debating installing some kind of diverter(s) inside the plenum to
direct more air onto #1 & #2.  Anybody do that to lower CHT's with
success?  How did you do it?  Got pictures? Controlling air movement is
such a funny thing, sometimes what seems logical or intuitive is exactly
the wrong thing to do! 

The fuel map is as good as I will be able to get it, until I get the new
prop.  At least I am not running at peak EGT in RPMs above 2200 now. 
That helped the temps a whole lot.

Now to getting the oil temp down some more. Right now I am not running
the fan on the secondary cooler as I see it as a summer time auxiliary
cooler.  With OAT in the 60's I shouldn't need it.  The oil temps were
OK, but a bit on the high side at a low power cruise speed of 165KTAS.
about 210F, but as soon as I fire-walled the throttle it started to come
up  and seemed to stabilize at around 230, though I didn't stay at that
power setting more than a couple of minutes.  With the IO360 my current
oil cooler was good enough but marginal.  On hot days I had to step
climb.  I don't have an exit scoop or air dam on the exit duct.  The
duct opening is flush with the fuselage. I'm really intrigued with Don's
idea of an Oil cooler flap that can be adjusted from the cockpit. When
flying with the IO360 I had too much cooling in the winter and marginal
in the summer. I would tape some of the cooler face in the winter so my
temps were hot enough to get a bit of warm air in the cabin.  With a
hinged controllable flap I could set it for whatever the conditions
were.  It would probably work out to 3 or 4 settings that covered all
scenarios.

Scott



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