REFLECTOR: Intake Measurement

Fri Jan 9 08:15:24 CST 2015

Since the top cowling comes so close to the top of the engine, I thought it would be a waste to build a separate cooling plenum, so I built the plenum baffles into the top cowling.  Then I built aluminum walls around the cylinders like you see on most air-cooled single engine installations, and put neoprene strips on the tops of the aluminum walls to seal against the top cowling.  The main reason I did this was so that when I removed the top cowling, I would be able to see the engine.   As the attached picture shows, I’ve got the air filter, mechanical fuel injection, and Plasma III coils all sitting on top of the engine block.  (I can’t find any pictures of the baffles in the top cowl.)

Doug Holub
2000 Standard FG w/ electric nose lift

From: Rene Dugas via Reflector 
Sent: Thursday, January 08, 2015 11:57 PM
To: paul barfknecht ; Velocity Aircraft Owners and Builders list 
Subject: Re: REFLECTOR: Intake Measurement

I have no boots with about 3/16" gaps and no cooling issues.  I've considered it but worry about it tearing and falling on the exhaust with subsequent fire.  If I had a problem that would probably be my first attempt at a fix though.

Sent from Rene's iPad. A pleasure.  Go Apple. 

On Jan 8, 2015, at 1:35 PM, paul barfknecht via Reflector <reflector at tvbf.org> wrote:

  My nacas extend about an inch into the engine compartment. My downdraft tunnels are installed by sliding over the nacas forward then pivoted down to attach (with all those beautiful screws) to the plenum. The tube over tube fit is a smidge less than snug at the firewall. If I am getting movement of the engine relative to the firewall there is the allowance. Clearance between the downdraft tunnels and the cowling is about a quarter inch as I recall.

    -----Original Message-----
    From: ajlz72756 at yahoo.com
    Sent: Thu, 8 Jan 2015 09:50:00 -0600
    To: ceraygun at inbox.com, tmann at n200lz.com, reflector at tvbf.org
    Subject: Re: REFLECTOR: Intake Measurement

    Beautiful workmanship, my question is, I keep seeing all of these photo’s of the down draft cooling plenums, without any rubber booted connection between the engine and the NACA scoop connection at the firewall. I have seen photo’s of the plenums with a rubber boot installed. So for those that I am seeing without, I know that my 300hp IO540 engine, using the standard MT three blade prop, is torqueing against the engine mount, at least 3/8 inch at full power, I know this because of the size holes I have had to cut around my exhaust pipes to keep them from hitting my cowling. My exhaust Exit holes started out with a 1/4 inch clearance all the way around, and I had to keep enlarging them, they are now oblong,  in the direction that the engine is twisting. It also seems to me that without some sort of rubber booted connection, that the engine vibration alone, would rip the connection off of the firewall. 

    My thoughts, others using the NACA down draft cooling will have to weigh in on this issue.

    -----------------------------------------
    Andrew Ellzey
    N151AJ IO540 300hp armpit updraft cooling

    From: paul barfknecht via Reflector 
    Sent: Wednesday, January 07, 2015 4:42 PM
    To: Thomas Mann ; Velocity Aircraft Owners and Builders list ; Velocity Reflector 
    Subject: Re: REFLECTOR: Intake Measurement

    I don't have the measurement, but thought you might be interested in a photo of my plenum on an SUV with an io360.  Ken Mishler , a Velocity Jedi Master created this masterpiece (with a little assistance from me) which has resulted in no concerns regarding cooling on my plane. removable sections allow good access to the top and front of the engine.
    Paul Barfknecht

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