Build a fan shroud to cool your beast! - S-10 Forum
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Build a fan shroud to cool your beast!

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Old 08-12-2009, 05:15 PM   #1
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Build a fan shroud to cool your beast!

As many of us already know, there aren't a lot of options for a shroud on a v8 S10. Sure, electric fans can be great. But a good setup can get pretty costly. You can just cut up your stock shroud, or maybe modify a shroud off of something else. That's not the best way to go about it either. For ideal cooling performance the fan blade needs to sit 1/3 to 1/2 way inside the shroud. Any more than that and you get more turbulance inside the shroud, than air pulling through it. Any less than that and you start pulling air from all over the place. The idea is to direct the airflow across the entire surface of the radiator towards the blade. A 16" or larger fan blade is recommended for a daily driver. The edge of the shroud needs to be 3/4" or less from the edge of the fan blade. The smaller gap the more efficient the draw-through will be. Just remember when you hit the gas the engine rocks some. Make sure you allow for that. Generally 1/2" of gap around the blade is good. Now that we have a basic understanding of what we need to do let's build a shroud. I picked up a piece of 26ga galvanized sheet metal from a local heating & cooling supply house. They use it to build a/c ductwork out of. The 3x8 sheet cost me about $15 and is plenty big to build any shroud. You'll also need a pair of metal snips to cut it with. If you don't have any you can pick some up when you get you metal for around $12. And a pair of leather gloves, there will be very sharp edges! Other tools needed will be a tape measure, square, drill, sheet metal screws or rivets, and a marker. The first thing you'll need to do is measure the core of your radiator. That's the finned section in between the tanks. You also need to measure from the core out towards your fan blade. Remember we want the shroud to cover half of that blade. That measurement will be your shroud depth. You will also need the measurements from top, bottom, left, and right, of the core to the edge of your blade (less 1/2" of course). Then finally a measurement for a mounting lip top and bottom. I also added about 1/8" for every bend I had to make. Now I suggest you draw this out on some paper and study it a bit. You will add the depth measurement to your core measurement. This is where the metal will be bent. And top and bottom you will add your mounting lip measurement. Here is what mine looked like after I drew it out on the metal.

To make a perfect cicle I used a hacksaw blade. I put a screw through one of the holes in the end, and drilled a new hole 8 1/2" inches away. That gave me a nice 17" circle. Now in my case I needed a 2-piece shroud. It was just a little extra work, but so much easier to remove and install. If you need a 2-piece shroud just add an extra 1" to your height measurement. Then after you cut it in half you will have enough metal to bend a 1/2" lip to bolt the two together. Here's what it looks like cut out of the full sheet of metal. The corners cut out are where it will meet after I bend it.


And here are the inner corner reinforcements. Basically just a rectangular piece of metal bent in a 90. I used sheet metal screws to temporarily hold it together. Later on these were replaced with rivets. It makes for less measuring and drilling that way.


Now don't worry about not having access to a metal brake. You can use a couple of 2x4's to make your bends, or a doorjamb. or bend it over a piece of plywood. I found it easiest to line my metal up with a crack between boards on my back deck. Then I used an old beat up carpenters square, and hit it with a hammer. That gave me a nice crease to start my bend with. Here's what it looks like all bent up. I also added a couple of extra creases to the shroud. This helps to stiffen it up.



Make sure it fits right. The top and bottom will be mounted. The sides just float about 1/4" away from the core. MAKE SURE THEY DON"T TOUCH! If so they will rub holes into your radiator within a matter of days. Now you're ready to wash it down good. Spray it with a little self-etching primer. And put some paint on it, I like the low gloss black engine paint.
And here it is after installation. I'll try to get a better pic tonight.


I hope this helps some of you, and feel free to use this information any way you like.
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Old 08-12-2009, 05:24 PM   #2
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Re: Build a fan shroud to cool your beast!

Nice work! But I prefer the direct fit approach of a stock 4.3 shroud and the "cone" shape it has.
Old 08-12-2009, 05:36 PM   #3
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Re: Build a fan shroud to cool your beast!

That's a great way to go if it fits. In this particular setup with the 4 row radiator, and custom built motor mounts, there was no other option.
Old 08-12-2009, 05:52 PM   #4
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Re: Build a fan shroud to cool your beast!

This is great stuff. Thanks for sharing your knowledge. There are many of us that can benefit from this. Keep up the good work and thanks for putting such clear pictures.
Old 08-12-2009, 07:27 PM   #5
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Re: Build a fan shroud to cool your beast!

And here are better pics of the shroud after install.




Old 08-12-2009, 07:29 PM   #6
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Re: Build a fan shroud to cool your beast!

looks like it will work good. i prefer a little more space between the shroud and radiator to pull more air, but obviously you have a v8 and are limited space wise.... looks good though. shoulda left it aluminum!
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