REFLECTOR: Reflector Digest, Vol 26, Issue 76

[Chuck Harbert]

Jack, I made them out of (the thin) 1/2" aluminum angle that you can buy at 
Loews or Home depot. I attached them with pop rivets and super glue. I had 
used silicone on the small VG's and one had come off in flight (didn't want 
the bigger ones going thru the prop or into the plenum). I used the same 
shape as the small VG's (rounded nose).

I placed them just in front of my small VG's (actually, I didn't remove the 
small ones in case it didn't work). I'd say they're about an inch in front 
of the very beginning of the 2 NACA inlets (a pair for each side/scoop). I 
tried to do a proportional placement compared to the small VG positioning 
per the template. At the front they are about 1 1/4" apart. They are about 1 
1/2" long. I tried to duplicate a picture of a V that had them (don't 
remember who's).

A friend of mine with a Cozy had a cooling problem and actually measured the 
airflow into his (underneath) big NACA scoop using an airspeed indicator. He 
was only getting about 100 kts when the plane was doing 150 kts, so he 
installed a couple of 2" tall VG's and and his cooling problem went away, 
plus he had full ram pressure to the servo.

I'm going to try the small VG's in front of the oil cooler first to see what 
happens. Then try the larger ones to see if there's a noticeable difference.

Chuck H

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Chuck,
What did you make the 1/2 inch VG's out off?
How many did you install
How far in front of the begining
of the NACA did you place the VG's?

Jack

After reading the recent postings on cooling, I installed larger VG's in
front of my overhead NACA inlets and my CHT temps were lowered significantly
(20-30F). Previously, I had used the small VG's (1/4" tall) and my CHT's
would get up to 425F on climb out on a not-very hot day (75F). I made up a
set 1/2" tall VG's and my CHT never got up to 400F on an 85F day on climb
out, plus they cooled to 360-370F in cruise. Next I'm going to see if the
small VG's will reduce oil temp, although it's not a problem (climb out
210F, cruise 185F).

At the Arlington Air Show, I talked for awhile with the Gary Garvens, CEO of
ECI (Engine Components, Inc-Titan cylinders www.eci2fly.com ) who said that
ideally you'd like your cylinder to run between 350-400F. Above that, you
start reducing the life because of the unique alloy that all the cylinder
head mfgs use. In WWII, the brits invented a high copper alloy of aluminum
which retains it stregth under hi temp, and it's still used today. Under
higher temps, the copper migrates from the crystalline structure to the
grain boundary when it causes cracks (technical term is intergranular stress
corrosion cracking). According to the Lyco manual you can go to 475F, but he
said they wouldn't likely last to TBO at these temps. Turbocharged cylinders
are hard on heads. He further recommended that you can rebuild your
cylinders one time, assuming they've not been run too hard or hot.

Chuck H
Std RG IO-360