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Free minder
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226 mm fan in 245 mm housing
I have found a replacement housing for my cracked one, but it is a 245mm, while the fan I have is 226 mm. Is there any harm in using this combination? I assume the air pressure will be lower, but I`d like to know if anyone has ever tried that, and what it does to the engine temperature.
 Aurel |
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04-04-2008, 05:52 PM
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Location: SoFLA
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I'm no aerodynamic engineer, but it looks like you'll be "losing" air around the edges. I'm sure an aerodynamic engineer will be chiming in soon, as there are more than a few here.
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04-04-2008, 05:58 PM
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I'm no aerodynamic engineer either, but I play one on the internet!
I wouldn't do it. The tight tolerance on the edge of the fan to housing provides a "seal" that allows the shroud to be pressurized allowing even airflow.
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Bill K. "I started out with nothin and I still got most of it left...." 83 911 SC Guards Red (now gone) And I sold a bunch of parts I hadn't installed yet. |
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04-04-2008, 06:14 PM
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That is totally unacceptable.
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Keeper of 356, 911, 912 & 914 databases; source for Kardex and CoA-type reports; email for info Researching 356, 911, 912 & 914 Paint codes, Engine #'s and Transmission #'s Addicted since 1975 |
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04-04-2008, 07:20 PM
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Dog-faced pony soldier
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Nope. Turbines need to have tight clearance between the shroud and blades. This is no exception. It's better than nothing, but it won't give your engine the cooling it was designed to have.
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A car, a 911, a motorbike and a few surfboards Black Cars Matter |
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04-04-2008, 07:30 PM
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At least it won't rub.
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Jeff '72 911T 3.0 MFI '93 Ducati 900 Super Sport "God invented whiskey so the Irish wouldn't rule the world" |
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04-06-2008, 05:39 AM
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04-06-2008, 06:19 AM
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Free minder
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Thanks guys. I bought a 245 mm impeller and put the 226 mm one for sale.
Cheers, Aurel |
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04-06-2008, 06:55 AM
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R&D guy
Join Date: Sep 2007
Location: the border between the states of inebriation & confusion
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You did the right thing...
Well, I am a hydrodynamics/hemodynamics research engineer, and I can assure you that the gap between the blade tips and the shroud are a critical parameter for performance. With increasing "tip gap" flow and pressure performance falls off significantly.
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04-06-2008, 07:16 AM
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Of course, the upside is you won't have to worry about the blades rubbing on the housing.
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Peace, Ron www.ronorlando.net 78SC Targa 3.2 SS, 964 cams, CIS, SSI's,Dansk Own a gun and you can rob a bank , own a bank and you can rob the world. |
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04-07-2008, 11:23 AM
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04-07-2008, 06:27 PM
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R&D guy
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A very important subject for all of us 911 enthusiasts, because doesn't driving or working on your pride & joy make your heart beat faster? Seriously: http://www.hemodynamicsociety.org/hemodyn.html |
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04-07-2008, 06:44 PM
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04-07-2008, 07:38 PM
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Aurel I have a good 245mm fan to do a trade if you wish.
Send me a PM if you are interested. Thanks Robert |
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04-07-2008, 08:13 PM
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dw1.
Would changeing a 5 blade fan for an 11 blade fan increase the cooling. Sorry to hijack the topic. Thanks in advance.
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04-07-2008, 09:26 PM
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I suppose if a 245mm fan was NLA at any price, then a clever machinist could fabricate a spacer of sorts to span the gap (only 9.5mm, btw). The shape of the spacer would have to be similar to the opening of the fan housing to smooth the entry of air and not create unnecessary air turbulence at the tip of the fan blades.
Either that or close the gap slightly by powder coating the fan with about 150 coats of paint, then with safety goggles, make sure the paint is really dry before cranking the engine. Sherwood |
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04-07-2008, 10:09 PM
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up-fixing der car(ma)
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yeah..nope.
[edited; saw he already got a 245mm fan]
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Scott Kinder kindersport @ gmail.com Last edited by YTNUKLR; 04-07-2008 at 10:19 PM.. |
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04-07-2008, 10:13 PM
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04-08-2008, 05:23 AM
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" Would changeing a 5 blade fan for an 11 blade fan increase the cooling.
Yes." "There are a ton of threads on this subject. Do a search for "5 blade fan, etc." After looking at 8 pages of the search result, I couldn't find any obvious titles that addresses the question; Why does a 5 blade fan increase the cooling more than an 11 blade fan? Sherwood |
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04-08-2008, 08:04 AM
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Free minder
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Quote:
Aurel |
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04-08-2008, 09:13 AM
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1983 Porsche SC
