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Building a custom Fan Shroud: Pic by pic
#1272396
07/23/12 01:06 AM
07/23/12 01:06 AM
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Joined: Jan 2003
Posts: 27,598
So Cal
autoxcuda
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I have a Champion 4 core 22” radiator that has performed well in my new 416 stroker small block. I’ve put 3458 miles the motor in 1 ½ years and driven a few times 80 miles @3700rpm to/from Willow Springs Raceway racing 60 laps/150 miles going about 130 mph @ 5800 rpm on straights. Radiator looks great inside, no rust, and no measured electrolysis. I run distilled water and Justice Brothers Radiator Cooler (RC/22P) and Justice Brothers Cooling System Protector ( CSP/1P). No major cooling problems, but I don’t run a fan shroud. Once in 88 degree heat I got stuck in road construction barely moving for 20 minutes. Motor got up to 215 degrees. The fan by itself just could not pull enough air without the car moving. Time for a shroud. When we first built the motor, the Champion upper radiator hose mounted way too close to the center and hit my 18” 5 blade MP fan kit. So I cut 1” off each blade of a 5 blade and made a 16” fan. The car still performed pretty darn good with a skimpy looking 16” fan and no shroud. I run the short Jaguar fan clutch (Hayden #2765) because of the thick radiator and 70-up taller aluminum water pump. The upper hose inlet tube had to be moved outward to fit any fan shroud. Radiator Works in Northridge, Ca did that and added a aluminum tab on top to help attach a shroud. The factory 68-69 and 70-72 V-8 shrouds needed cutting to end up with a marginal shroud. So I traded some parts with Troy and he said he’d make me a shroud if I helped. Here’s the pictures that tell the story….  That aluminum angle is 1/16" thick and 3/4" by 1/2". 48" long piece. The 20 gauge aluminum sheet was $21.75 for a 24" x 48" piece.  
Last edited by autoxcuda; 07/24/12 01:50 PM.
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Re: Building a custom Fan Shroud: Pic by pic
[Re: astjp2]
#1272398
07/23/12 02:42 AM
07/23/12 02:42 AM
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Joined: Jan 2003
Posts: 27,598
So Cal
autoxcuda
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We put these on the existing Champion holes. But the aluminum was too thick for them even after I bent them out some. So we thinned the alumnum out some and also made the shroud end rails fit more flush.  When the radiator was still in the car I marked the centerline of the water pump translated to the radiator itself. This way we would know where to start the center of the fan shroud opening later. I also had the upper shroud tab welded onto the radiator along this centerline. We added foam to make a tight seal and to protect the shroud from rubbing into the radiator tubes/fins.  Foam detail
Last edited by autoxcuda; 07/23/12 02:51 AM.
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Re: Building a custom Fan Shroud: Pic by pic
[Re: autoxcuda]
#1272400
07/23/12 10:06 AM
07/23/12 10:06 AM
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Joined: Dec 2003
Posts: 23,642
Here
jcc
No soup for you!!!
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No soup for you!!!
Joined: Dec 2003
Posts: 23,642
Here
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Nice job and nice thread presentation.
And a little OT, I have always pondered the original concept of a fan shroud. Is it to move air by the engines fan thru the largest area of of the radiator by the fan, or is it to make the fan move the most amount of air thru improved efficiency by good shroud design (ie a simple tight fitting ring), albeit thru a smaller area of the radiator?
Seems to me the first goal would be best for low vehicle speed use, and the second more ideal for high speed use, since it would present less blockage of the radiator since most shrouds reduce airflow area at some point. However simply over sizing the radiator would, imo mask whatever results one observed to the above solutions
I'm with Helmuth Hübener, and no soup is being served today.
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Re: Building a custom Fan Shroud: Pic by pic
[Re: autoxcuda]
#1272402
07/23/12 02:34 PM
07/23/12 02:34 PM
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Joined: Jan 2003
Posts: 27,598
So Cal
autoxcuda
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To find optimum hole diameter for a shroud take the fan diameter and add 10% of the fan diameter. So for my 16" fan I added 1.6" to 16" and cut my hole at 17.6".
The optimum depth of the shroud is when the pitch of the fan blades are showing 1/2 in and 1/2 out of the shroud.
That info came from a past employee of a large automobile and industrial radiator manufacture explained to me the design of a fan shroud.
Last edited by autoxcuda; 07/23/12 02:35 PM.
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Re: Building a custom Fan Shroud: Pic by pic
[Re: autoxcuda]
#1272404
07/23/12 10:01 PM
07/23/12 10:01 PM
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Joined: Aug 2003
Posts: 1,062
Amherst,NY
challengermike
super stock
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super stock
Joined: Aug 2003
Posts: 1,062
Amherst,NY
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Quote:
To find optimum hole diameter for a shroud take the fan diameter and add 10% of the fan diameter. So for my 16" fan I added 1.6" to 16" and cut my hole at 17.6".
The optimum depth of the shroud is when the pitch of the fan blades are showing 1/2 in and 1/2 out of the shroud.
That info came from a past employee of a large automobile and industrial radiator manufacture explained to me the design of a fan shroud.
Is a 17.6 hole big enough to not allow the fan to hit it when the engine mounts flex?
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Re: Building a custom Fan Shroud: Pic by pic
[Re: challengermike]
#1272405
07/24/12 01:13 AM
07/24/12 01:13 AM
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Joined: Jan 2003
Posts: 27,598
So Cal
autoxcuda
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Quote:
Quote:
To find optimum hole diameter for a shroud take the fan diameter and add 10% of the fan diameter. So for my 16" fan I added 1.6" to 16" and cut my hole at 17.6".
The optimum depth of the shroud is when the pitch of the fan blades are showing 1/2 in and 1/2 out of the shroud.
That info came from a past employee of a large automobile and industrial radiator manufacture explained to me the design of a fan shroud.
Is a 17.6 hole big enough to not allow the fan to hit it when the engine mounts flex?
That's a little over 3/4" all the way around. I've driven it about a bunch. No problems shift hard at 5500 rpm from 1st to 2nd.
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Re: Building a custom Fan Shroud: Pic by pic
[Re: autoxcuda]
#1272406
07/24/12 01:22 AM
07/24/12 01:22 AM
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Joined: Jan 2003
Posts: 27,598
So Cal
autoxcuda
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Here's a detail of the foam seal at the bottom of the shroud. At this point I also added foam all around the top of the shroud (not shown in previous pics).  I wanted a durable finish on the shroud that didn't need the maintainance of bare aluminum. So I painted it VHT wrinkle paint baked in an oven. I can run my fingernail against this paint enough to file it and it will not scratch.
Last edited by autoxcuda; 07/24/12 04:15 PM.
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Re: Building a custom Fan Shroud: Pic by pic
[Re: 1962Savoy]
#1272412
07/24/12 04:06 PM
07/24/12 04:06 PM
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Joined: Jan 2003
Posts: 27,598
So Cal
autoxcuda
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Quote:
Thanks For the info I did it as well and it turned out perfect. I engine turned the shroud and then clear coated it.My fan is only 1/2 inch away from the edge of the opening and I haven't had any clearance problems. 
Looks like someone has access to a TIG welder. 
I like the engine turned finish. Works well with your engine compartment. It ran through my mind, but I went wrinkle to complement my other wrinkle stuff.
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Re: Building a custom Fan Shroud: Pic by pic
[Re: bobs66440]
#1272413
07/24/12 04:11 PM
07/24/12 04:11 PM
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Joined: Jan 2003
Posts: 27,598
So Cal
autoxcuda
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Quote:
Nice work. I made one for the 22" rad I had installed also but it was temporary to see if it made any difference in the engine temp. It didn't. I have an 18" fan, so I couldn't keep the hole inside the core size. I've since installed a new Champion 26" and plan to build another one from bare stock this time.
Was your engine temp issue only at idle without the car moving? Or was it with the car moving?
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Re: Building a custom Fan Shroud: Pic by pic
[Re: autoxcuda]
#1272414
07/24/12 04:16 PM
07/24/12 04:16 PM
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Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
bobs66440
top fuel
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top fuel
Joined: Mar 2010
Posts: 1,880
Out in Left Field, NY
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Quote:
Quote:
Nice work. I made one for the 22" rad I had installed also but it was temporary to see if it made any difference in the engine temp. It didn't. I have an 18" fan, so I couldn't keep the hole inside the core size. I've since installed a new Champion 26" and plan to build another one from bare stock this time.
Was your engine temp issue only at idle without the car moving? Or was it with the car moving?
It was only at idle. On the highway or any speed over 20mph or so it was fine.
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Re: Building a custom Fan Shroud: Pic by pic
[Re: autoxcuda]
#1272415
07/24/12 05:00 PM
07/24/12 05:00 PM
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Joined: Jan 2003
Posts: 27,598
So Cal
autoxcuda
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Here's a picture of the fan shroud installed.
The JAZ over flow bottle on the right has a valve so you can drain it when and where you want. Not that its ever had anything overflow into it of significance.
Last edited by autoxcuda; 07/24/12 05:02 PM.
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