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Old 07-24-2009, 01:01 PM
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Fan shroud VS no fan shroud

What is your opionion on having an electric fan with out a shroud or with a shroud and why.

I am seeing many different options on this. Benefits to both ways.
Curious to see what you guys have as a set up and how well it works.

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Old 07-24-2009, 01:22 PM
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Do Not Run An Electric Fan Without A Shroud!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Do Not Run Any Fan Without A Shroud!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!
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Old 07-24-2009, 01:51 PM
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Let's get ready to rumble!!

My electric fan works just fine with no shroud. Probably would be a little more efficient with a shroud, but it's getting the job done without one.
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Old 07-24-2009, 01:58 PM
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LOL... The article on a better Pontiac cooling system says they took off the shroud because it resticts the flow over 50mph. Their system was cooling great at low speeds but not as well fast. Taking off the shroud for them was more beneficial. They did have a few other things done to allow better cooling.

As for me, because I live in Southern California, I am going with a shroud because of sitting in traffic and tooooons of stop lights.
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Old 07-24-2009, 02:07 PM
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anyone that runs without a shroud is asking for trouble down the road!
the car MFG didnt do research and develop them because they look good etc.
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Old 07-24-2009, 03:08 PM
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Quote:
Originally Posted by 66Ponty
What is your opionion on having an electric fan with out a shroud or with a shroud and why.

I am seeing many different options on this. Benefits to both ways.
Curious to see what you guys have as a set up and how well it works.
The fan shroud allows a smaller radiator to be used. The most critical cooling situation for the OEMs designing for ma/pa America driving to the grocery store is hot idle, stopped in traffic cooling. In this condition without a shroud the only air passing thru the radiator core is that area directly in front of the fan. This leaves a lot of core area doing not much of anything regarding heat transfer to the atmosphere. The shroud is used to enclose the entire core perimeter at the radiator end and covers the diameter of the fan and about 1/2 the blade's twist depth. This does two really useful things:

1) It encloses the entire area of the core so that when vacuum is formed by the spinning fan, air flows thru the entire surface area of the core greatly increasing the radiator's effectiveness as there are no dead zones where there isn't core working to transfer heat.

2) The fan running partially shrouded is more efficient than an open ended fan, the shroud acts like modern winglets on jet transports like the Airbus 320 and Boeing 737. It catches the air flow moving along the length of the blade and stops it from being slung off the tip. Instead that air is forced to escape in the direction or the rest of the air flow which is at 90 degrees to the fan's plain of rotation. The trick here is keeping the only part of the fan inside the shroud, when all of it is contained, you get harmonic turbulence that reduces flow below that of an open fan, so the rear part of the blade twist is left outside the shroud to provide a little outward bleed of air which stops the harmonics.

Bogie
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Old 07-24-2009, 05:09 PM
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Here's the simple shroud I made for the electric fan on my sedan delivery. The step-by-step photos of fabrication are here in my journal. In general I believe you will achieve more efficient cooling with a good shroud than with no shroud...but obviously their might be exceptions.

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Old 11-21-2009, 07:51 PM
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The main thing to remember about a shroud is that the air is pulled through the whole condenser vs. one that doesn't have a shroud. The shrouds do restrict air flow at higher speeds. Some companies put rubber flaps on the shroud that stay closed at low speeds and open at higher speeds. Hope this helps.
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Old 11-22-2009, 07:26 PM
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I've done it without and it didn't work at all for me especially when going in slow speeds. I found a dual fan setup from a 4th gen f-body and they have a built in fan shroud with 2 flaps for highway speed wind pass through. This works great and I have absolutely no overheating for the first time in 10 years of trying different fans and setups both mechanical and electrical. 3rd gen f-bodys are notorious for getting hot. I think it just depends on your car and the setup that will determine what you need but it won't hurt to have the shroud there that's for sure. Here's mine..
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Old 11-22-2009, 08:20 PM
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I ''never'' ran a shroud with a elect. fan.. Never needed too. And never had one problem. Not one time. And we have some very hot days here..

The key is...The right size rad.. and the right elect fan.. If one is wrong it will fight the other..
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Old 11-22-2009, 09:29 PM
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My electric fan is in the factory mechanical fan shroud, works great.
Shane
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Old 11-22-2009, 11:11 PM
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I have no shroud

I run a 351W rated at 365Hp. I have redundant electric fan systems. I installed radiator for 390. I originally ran a fan shroud but removed it years ago. The second fan system rarely kicks on. I test it from time to time to verify it is working. The one fan keeps engine temps in the normal range even on hot days. I set the thermostat to kick on just above normal cruise temp.
Seems to me if your radiator has high enough capacity a fan shroud is not needed.
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Old 03-22-2013, 07:34 PM
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Shroud - yes or no

Thanks guys. I am shopping for a Fan with Shroud for my SBC 55.2 3100 PU (w/ 302 = ex Z/28) which will have a March serpentine system on the front. Had 32" aluminum radiator when bought (with NO radiator support ?? duh), but have gone back to the stock '55 Radiator Support and a 3 core '55 Radiator. Will have an A/C condenser and a Radial (finned tube) Trans Cooler on the front of the radiator. You guys convinced this quite senior 1st-time rodder to use the Shroud. Probably going with a CCI-1780 vice the 1740 'cuz I do not wish to mount it use Zip-Ties. The extra width of the 80 will let me reach the Radiator & Support mounting holes at 25.5" (I hope). Still checking the height dimension. Darn odd how many fan sellers do NOT post ALL the dimension info we need to choose.
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Old 03-23-2013, 06:36 AM
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Check out Spal fans......the have the lowest staic pressure drop of most any electric fan on the market.
Static pressure drop is the drop in cfm when you attach the fan to the radiator. Some fans can drop as much as half the advertised CFM. Spal drops the least.
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Old 03-23-2013, 06:52 AM
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Your going to have to find out what your set up likes best... I'd try no shroud first...

Many say an aluminum radiator flows air better then brass so a shroud isn't needed... I just installed a Champion aluminum radiator in front of my Pontiac 462, I'm going to try both, I like having just the basics on my car, lowering weight is always my goal with a Bonneville...

Last edited by Bonneville462; 03-23-2013 at 07:03 AM.
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