REFLECTOR: CHT's

[Scott Derrick]

Rene, what engine are you running? 

here's an early picture of my plenum.

http://tnstaafl.net/canards/img134.jpg

it was from the factory for a 550, close enough for a 520.  The
attachment has changed but the overall shape is identical.

Scott

Rene Dugas wrote:
> I don't know what your naca to plenum looks like but mine is attached and no
> diverter was needed.  All my CHT's are within 20 degrees.
> Hope it helps somehow.
> Rene'
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Scott Derrick
> Sent: Sunday, October 18, 2009 3:10 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: REFLECTOR: CHT's
>
> 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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