| Re: [GMCnet] Fan Shroud questions - one more thought [message #163161] |
Fri, 16 March 2012 12:33  |
enate98690
Messages: 23
Registered: January 2012
Karma: 0
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Junior Member |
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Hey Steve,
One more thought, there was SOME, good reason GM did the fan ring as they did. It clearly was not the cheapest, nor the most easily manufactured fan assembly by any means. Soooooo, that should tell you volumes as auto manufacturing, even with the GMC motorhomes, is all about cost saving where possible.
Thanks,
Keith Lee
-----Original Message-----
>From: Steve Southworth <midlf@centurytel.net>
>Sent: Mar 15, 2012 6:20 PM
>To: gmclist@temp.gmcnet.org
>Subject: [GMCnet] Fan Shroud questions
>
>
>
>I'm pulling the radiator and fan shroud off my front clip and am somewhat intrigued by the way GMC did this. On my 75 Vette the fiberglass fan shroud extends back over the fan, with some clearance between the fan blade tips and the shroud, enough to get a fan belt past. On the GMC, as most of you are aware, the fan "venturi ring", is mounted to the engine with a very tight clearance to the fan blades. This is an expensive method, parts and assembly time, compared to some of the alternatives used by GM.
>
>My question(s):
>
>Why did the GMC MH use this method?
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>Was it the method used on the Toro?
>
>What is the purpose of the tight tolerance between the fan and the venturi ring? Noise reduction? Fan efficiency?
>
>Just curious.
>--
>Steve Southworth
>1974 Glacier TZE064V100150 (for workin on)
>1975 Transmode TZE365V100394 (parts & spares)
>Palmyra WI
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| Re: [GMCnet] Fan Shroud questions - one more thought [message #163223 is a reply to message #163161] |
Fri, 16 March 2012 21:01  |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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Senior Member |
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| enate98690 wrote on Fri, 16 March 2012 12:33 |
Hey Steve,
One more thought, there was SOME, good reason GM did the fan ring as they did. It clearly was not the cheapest, nor the most easily manufactured fan assembly by any means. Soooooo, that should tell you volumes as auto manufacturing, even with the GMC motorhomes, is all about cost saving where possible.
Thanks,
Keith Lee
|
Yeah that thought process was part of what was behind my curiosity question. Generally I don't like to change something until I understand why it was originally done the way it was.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] Fan Shroud questions - one more thought [message #163257 is a reply to message #163161] |
Sat, 17 March 2012 09:06 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| enate98690 wrote on Fri, 16 March 2012 13:33 |
Hey Steve,
One more thought, there was SOME, good reason GM did the fan ring as they did. It clearly was not the cheapest, nor the most easily manufactured fan assembly by any means. Soooooo, that should tell you volumes as auto manufacturing, even with the GMC motorhomes, is all about cost saving where possible.
Thanks,
Keith Lee
-----Original Message-----
>From: Steve Southworth <midlf@centurytel.net>
>
>I'm pulling the radiator and fan shroud off my front clip and am somewhat intrigued by the way GMC did this. On my 75 Vette the fiberglass fan shroud extends back over the fan, with some clearance between the fan blade tips and the shroud, enough to get a fan belt past. On the GMC, as most of you are aware, the fan "venturi ring", is mounted to the engine with a very tight clearance to the fan blades. This is an expensive method, parts and assembly time, compared to some of the alternatives used by GM.
>
>My question(s):
>
>Why did the GMC MH use this method?
>
>Was it the method used on the Toro?
>
>What is the purpose of the tight tolerance between the fan and the venturi ring? Noise reduction? Fan efficiency?
>
>Just curious.
>--
>Steve Southworth
|
Keith and Steve,
I did fans for a while - too.
GM must have identified a cooling problem during vehicle testing. That would be the only reason for that configuration.
Steve, I can tell you that the nozzle ring attached to the engine is what in the industry is called a "Golden Fix". A "Golden Fix" is a bar cost best solution. (If we do this, we know it will be as good as it can be. We can try to cost reduce it later.) Sometimes also referred to as a Golden Band-Aid.
It is better for fan efficiency than it is noise.
The trailing edges extending out of the shroud are not very good for noise, but add to the efficiency. Fan noise has not been a big issue until cars and engines got quiet enough for it to matter.
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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