REFLECTOR: CHT's

[Scott Derrick]

They actually expand to about twice the area from the firewall to the
plenum.  The expansion is in the depth of the ducts, not the width.

Scott

John Tvedte wrote:
> If I had all that room between the two, I'd angle each of them inboard - to allow for more expansion room - better pressure recovery.
>
> John
> ________________________________________
> From: reflector-bounces at tvbf.org [reflector-bounces at tvbf.org] On Behalf Of Scott Derrick [scott at tnstaafl.net]
> Sent: Monday, October 19, 2009 2:25 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: CHT's
>
> 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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