REFLECTOR: CHT's

Rene Dugas dugasd at bellsouth.net
Mon Oct 19 18:16:59 CDT 2009


IO-540 260 hp
Rene'
My NACA's are 1 inch wider than recommended by the factory 9 years ago.  
Second plenum.  First exploded when I started the engine without the plenum
bolted down and caught in prop.  Not a piece was bigger than 4 x 4 inches. I
have the slip joint half way up rails with about 1/8th inch opening.  No
seal has ever been needed.
RD

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Scott Derrick
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
>
>
>
>
>
> CyberDefender has scanned this email for potential threats.
> Version 2.0 / Build 4.03.29.01
> Get free PC security at www.cyberdefender.com
>   
>
> ----------------------------------------------------------------------
> --
>
> ----------------------------------------------------------------------
> --
>
> _______________________________________________
> To change your email address, visit
> http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery!  www.tvbf.org/gallery user:pw = tvbf:jamaicangoose 
> Check new archives: www.tvbf.org/pipermail Check old archives:
> http://www.tvbf.org/archives/velocity/maillist.html



CyberDefender has scanned this email for potential threats.
Version 2.0 / Build 4.03.29.01
Get free PC security at www.cyberdefender.com



More information about the Reflector mailing list