REFLECTOR: Duct ventillation

[Brent Bourgeois]

Jerry,
Check this site out. http://www.n91cz.com/
It shows a step by step method to prove or disprove the success of any changes you might make. My experience shows its almost always the exit that can be improved. I think you might be on to something. Before and after photos?  You are correct, the cowl will pressurize the wire ducts and they need to be sealed at the firewall. 
Brent
N61VB
Std RG

--- On Wed, 10/21/09, Jerry Teitsma <jerryteits at comcast.net> wrote:
 

From: Jerry Teitsma <jerryteits at comcast.net>
Subject: REFLECTOR: Duct ventillation
To: reflector at tvbf.org
Date: Wednesday, October 21, 2009, 1:36 PM


I have also experienced very hot temps in the ducts both on the side carrying the oil lines and on the other side.  I stopped or reduced this temporarily by stuffing the duct opening at the firewall.  I have reasoned that I am building up too much pressure under the cowling.   I have a Franklin engine in a standard size velocity and the exit area at the prop is quite congested.  I am attempting to solve the perceived pressure build-up by building a reverse scoop on the bottom of the cowling to pull air out of the engine compartment.  This should also aid in cylinder head cooling.  I have not yet flown with the modification so time will tell.

Jerry Teitsma
Velocity 173 FG
Granby, CO
N241JT 
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