REFLECTOR: Cooling VG's

Laurence Coen lwcoen at hotmail.com
Tue Jul 18 14:13:39 CDT 2006


Jack,

I used 1/2"x3/4" angle aluminum to give me 3/4" tall VG's in front of my oil 
cooler inlet.  I stuck them on with RTV.  I pressed them down firmly and 
didn't even have to tape them in place.  I flew them 24 hours later.

Larry Coen

----- Original Message ----- 
From: <J.F.Sheehan at larc.nasa.gov>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Tuesday, July 18, 2006 1:37 PM
Subject: Re: REFLECTOR: Cooling VG's


> 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
>>
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