Homemade fan shroud

MichaelT

MichaelT

Well-Known Member
Joined
Sep 7, 2007
Location
Charlotte
I am in the process of making a fan shroud for my CJ5 out of an aluminum sheet pan that I have. I do not have a clutch fan and will be running a 15" electric fan. So far I have cut the pan for the radiator hoses and made a foam gasket to go around the edge and try and seal off the outer parts of the radiator and I have also have cut out a hole in the center for the fan. Right now I have it so that the fan will bolt up to the shroud instead of sticking it right on the radiator. I am thinking about using great stuff foam to seal up the gap between the outside of the fan guard and the fan. My thinking in doing this is that I can get air flow through the whole radiator in doing this rather than having the fan mounted to the radiator and just getting forced air through that 15" circle.

Am I overthinking this or should I just:
A-continue with the plan and mount the fan to the shroud and try and get it airtight?
B-mount the fan straight to the radiator and just have the open hole behind the fan?
C-mount the fan straight to the radiator and ditch the shroud completely?

This jeep is trail only and will not see much street time at all so it will be going slow and not getting much air flow in its own.

Thanks -Mike
ImageUploadedByTapatalk1398781807.145801.jpg
 
go with A. Mount the shroud to the radiator and the fan to the shroud. The farther away you can get the fan from the radiator surface the more effectively it will pull air from the entire core vs just the 15" circle.
 
Cool, looks like I will continue as I had originally planned. I would have finished it last night but ran into a snag when I went to mount it because the fan was touching a pulley. When I tried to space the fan in more the bolts that I had were too short and couldn't find any longer ones. So I'm guessing that I should try and make this as airtight as I can so it's not pulling air from around the shroud, correct?
 
What gap do you anticipate having between the shroud and the radiator?

I would use rubber/closed-cell foam weather-stripping for the sealing... not something from a can.
 
I've got a 2'x2' sheet of pink foamlike insulation that I have cut to fit around the perimeter of the shroud. I was going to use the spray foam to seal the gap (~1/4") between the fan guard and the shroud and whatever little areas that the foam sheet might not seal up
 
I'll have to see what I have sitting around, that gap will probably be bigger after I space it inwards to clear the pulley though
 
A bit of gap isn't going to hurt much. A little will actually increase air flow around and through the entire unit. Think of a carb and the jets. The shroud will aid in directing where the most of the air is pulled from but allowing extra volume to come through the sides will created some extra vacuum and more air will flow. Your fan will not work as hard and you'll maintain more useable flow, even when the core gets gunked up some.
 
Several years back, I combined 3 shrouds, I got at Pull A Part. A few pop rivets, & fiberglass help from a body man, looks factory. I've also been advised that the Blade are to be centered [1/2 blade in/ 1/2 blade out] to the outer edge of the shroud. Or as close as you can space it.
 
paradisePWoffrd said:
go with A. Mount the shroud to the radiator and the fan to the shroud. The farther away you can get the fan from the radiator surface the more effectively it will pull air from the entire core vs just the 15" circle.
Click to expand...

X2

Seal the fan to the shroud with something too.
 
I wouldn't use the pan if I were you.
It looks like you'll only have 1/2 to 1' clearance, so the majority of he cooling will only come from in front of the fan.

Cooling power increases dramatically and engine pull reduces dramatically the farther the fan gets from the radiator and he bigger the shroud. (Not going into specifics, but proved this on stock cars years ago).
Also, an airtight fit isn't neccessary.
And what was said about centering the blade on he edge of he shroud is correct.
Also, the opening for the fan should only be about 1/2" - 1" bigger than the fan.


Matt
 
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