| [GMCnet] Fan shroud question for the brain trust [message #263697] |
Tue, 07 October 2014 14:00  |
glwgmc
Messages: 1014
Registered: June 2004
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From one of the hot rod forums and also the opinion of one trusted GMC source:
"I read a very good article many years ago about fan/fan shroud technology and it was stated that for optimal efficiency the fan blades should be 50% in the shroud and 50% outside the shroud....this is when looking at the edge of the fan blades."
That is what one gets with the split fan shrouds. The blade is half in and half out of the shroud. Is that where it should be to cool our beasts properly?
Great job by all at the French Camp, CA rally that ended Monday, btw!
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed & hand crafted
in the 1907 former Masonic Temple building
in historic Kerby, OR
http://jerrywork.com
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] Fan shroud question for the brain trust [message #263702 is a reply to message #263697] |
Tue, 07 October 2014 14:54  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
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Interesting because Dick Paterson made that same comment in a conversation last week at Chippewa Falls. He said if it is fully inside the shroud it makes more noise with no improvement in air flow.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Fan shroud question for the brain trust [message #263703 is a reply to message #263702] |
Tue, 07 October 2014 14:57 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
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While we are in the area, you should look at the new 10 blade plastic fan for the GMC. It was introduced at the rally last week. One was given away in the prize drawings and a seminar held on it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Fan shroud question for the brain trust [message #263706 is a reply to message #263703] |
Tue, 07 October 2014 15:14 |
powerjon
Messages: 2446
Registered: January 2004
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Although we did not go to the GMCMI convention last week in Wisconsin, I had a friend pick one up for me as I pre-bought one before the convention. Can’t wait to get my hands on it at the GMCGL rally this coming weekend at Turkeyville.
JR Wright
78 Buskirk Stretch
75 Avion
Michigan
On Oct 7, 2014, at 3:57 PM, Ken Burton wrote:
> While we are in the area, you should look at the new 10 blade plastic fan for the GMC. It was introduced at the rally last week. One was given away
> in the prize drawings and a seminar held on it.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Fan shroud question for the brain trust [message #263711 is a reply to message #263697] |
Tue, 07 October 2014 16:21 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
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Jerry 50% is a good approximation depending on the blade design. I think some designs benefit from even more exposed blade as a lot of air comes off the blade tips in a direction away from center hub. An old 240V condesing unit fan is good to play with by loosening the set screw and adjusting the blade on or off the shaft. The tips on the GM steel fans are swept back so this is quite true. Not sure what is optimal depth on the plastic fan as tips don't flair back.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Fan shroud question for the brain trust [message #263720 is a reply to message #263703] |
Tue, 07 October 2014 17:27 |
Joe Weir
Messages: 769
Registered: February 2013
Location: Columbia, SC
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Ken Burton wrote on Tue, 07 October 2014 14:57While we are in the area, you should look at the new 10 blade plastic fan for the GMC. It was introduced at the rally last week. One was given away in the prize drawings and a seminar held on it.
Who makes it/carries it?
76 Birchaven - "Wicked Mistress" - New engine, trans, alum radiator, brakes, Sully airbags, fuel lines, seats, adult beverage center... those Coachmen guys were really thinking about us second hand owners by including that beverage center...
Columbia, SC.
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| [GMCnet] Fwd: Fan shroud question for the brain trust [message #263768 is a reply to message #263720] |
Wed, 08 October 2014 10:28 |
powerjon
Messages: 2446
Registered: January 2004
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The new 10 blade plastic fan is being sold by John Biwersi. He can be reached at jbiwersi@mac.com His phone number is 651 seven 7 nine-six 4 nine 8. This is the same guy that does 3.21 final drives and he lives in MN. His last cost at the convention was a price of $105 plus a $20 charge for USA ground shipping.
See the following:
or
http://tinyurl.com/q7x3ekk
or
http://tinyurl.com/m8bqm5s
JR Wright
78 Buskirk Stretch
75 Avion
Michigan
Begin forwarded message:
> From: Joe Weir
> Subject: Re: [GMCnet] Fan shroud question for the brain trust
> Date: October 7, 2014 at 6:27:16 PM EDT
> To: gmclist@temp.gmcnet.org
> Reply-To: gmclist@temp.gmcnet.org
>
> Ken Burton wrote on Tue, 07 October 2014 14:57
>> While we are in the area, you should look at the new 10 blade plastic fan for the GMC. It was introduced at the rally last week. One was given
>> away in the prize drawings and a seminar held on it.
>
>
> Who makes it/carries it?
>
> --
> 76 Birchaven - New engine, trans, aluminum radiator, brakes, airbags, fuel lines, seats, upholstery, adult beverage center... those Coachmen guys were
> really thinking about us second hand owners...
> Columbia, SC.
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Fwd: Fan shroud question for the brain trust [message #263911 is a reply to message #263814] |
Fri, 10 October 2014 13:16 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
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I only worked in cooling at Jeep for a year to correct the 3.7 fiasco, but as a direct result of that and the 2001 purge, I worked at Hayes Cooling for another year.
At Jeep, they just set the blade protrusion where the supplier told them to set it. If it didn't work, then I got to play.
At Hayes, we ran our design blade in an ASHRE tunnel with a shroud like the customer had designed and determined what that protrusion should be.
As it goes, it varies by blade, but most of the curved section (a curve when you look at the end of the blade) want to be about 40% out of the shroud in a typical automotive arrangement where you are trying to draw air through a heat exchanger (radiator). I was told that flat blade fans - again this is looking at the end of the blade - get less but still not zero, advantage from this. But, I never ran one.
This is a result of the change in curvature to more pitch makes that makes the trailing edge behave much like a centrifugal fan instead of a propeller blade. It essentially gets you some additional air movement for not much more power. That means better efficiency as an engine cooling fan.
Molded plastic fan blades can make great advantage of the blade section. One of the reasons I parted company with Hayes was that I really thought we could use the molded fans take advantage of the data from the NACA studies done in the late 30's.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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