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Old 01-10-2008, 12:09 PM   #21
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Originally Posted by jayc72 View Post
At what speed does airflow from the car moving overcome the fans?
whats the CFM of those fans?

Whats the surface area of the radiator?
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Old 01-10-2008, 12:31 PM   #22
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not sure on surface area of radiator
the fans are rated at 1500CFM each, so total of 3000CFMs safe to say?
there are better ways to build the shroud im sure, but i was really thinking that this would be sufficient for my needs...

if i had the means i would build one that looks something like this
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sorry for tge lack of skillz in paint, its the only program i have
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Old 01-10-2008, 12:33 PM   #23
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well what was the size of the lexan? Use that for now
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Old 01-10-2008, 12:46 PM   #24
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i didnt measure anything, i lined the lexan up with the radiator and marked accordingly, the lexan was a bit taller so i dremmeled it off and then just dremmeled the loops for rad. feed and return
i think ill be ok with this setup once the shroud is sealed
i may start developement on the next shroud at a later time out of ABS or lexan again, but i think ill make a mold and then just use heat gun to bend the lexan/ABS over the mold...that should be easily achieved
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Old 01-10-2008, 12:59 PM   #25
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Quote:
Originally Posted by whaaamx5 View Post
not sure on surface area of radiator
the fans are rated at 1500CFM each, so total of 3000CFMs safe to say?
there are better ways to build the shroud im sure, but i was really thinking that this would be sufficient for my needs...

if i had the means i would build one that looks something like this

sorry for tge lack of skillz in paint, its the only program i have
3000 cfm, in ideal conditions with no restriction (aka a rad) infront of them.

A local forum member found that his stock fans flowed more with a rad infront of them then generic ebay type.
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Old 01-10-2008, 01:05 PM   #26
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Quote:
Originally Posted by whaaamx5 View Post
not sure on surface area of radiator
the fans are rated at 1500CFM each, so total of 3000CFMs safe to say?
there are better ways to build the shroud im sure, but i was really thinking that this would be sufficient for my needs...

if i had the means i would build one that looks something like this

sorry for tge lack of skillz in paint, its the only program i have
Okay someone can correct me on this issue because I'm dense:

1) Is this shroud simple going to be flat on the back of the radiator? from your "layout" it looks flat, but your pic shows it inverted. I could see a significant gain from the wedge approach, especially with an extractor hood, and a significant loss from the "flat approach". I agree with olderguy's assessment that the "flat" design will compromise high speed airflow.

2) It looks like like fans are built "into" your shroud. If you use the wedge approach, personally I would put the fans on the radiator themselves (see everyone elses GS install pics). It would really "seal" off the area, rather then leaving two gaping fan holes that would release pressure. Your extractor hood should release enough pressure as it is. I'm sure you thought of this, but the paint program just wouldn't let you express it
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Old 01-10-2008, 01:11 PM   #27
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If the fans are on the radiator it defeats the porpose.
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Old 01-10-2008, 01:26 PM   #28
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on my original shroud, the shroud doesnt sit on the radiator, there is about 1" gap
on the proposed idea, the point is to direct all airflow that goes through the radiator towards the fans, so even if fans are off the airflow still finds its way to a lower pressure area, thats why i have the fans leaning up towards the vent in the hood

the fans are meant to be flush with the shroud surface
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Old 01-10-2008, 01:32 PM   #29
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its fine
just seals the edges. dont over think it and worry about it. it'll work more than efficiently.
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Old 01-10-2008, 01:40 PM   #30
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if it doesnt work i can always change it or add a pcpro or two, right? QUACK lol

but anyways, i cant explain this well nor draw it up well, but here is another perspective on what i think would be the best solution
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Old 01-10-2008, 02:14 PM   #31
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Looks good to me. I need to think of something like that. Temps in my car (even before my new larger intercooler) will increase on the highway until the fans turn on, then it goes down very quickly. Constant cycle, even in the winter. I have lots of open spaces/very little sealed.
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Old 01-10-2008, 02:25 PM   #32
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Jeez, you put a lot of thought into this Dan. lol Where did you source the lexan from?
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Old 01-10-2008, 02:56 PM   #33
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1" off the rad surface is definitely adequate- that's what I did, but your second drawing is a far more interesting project

sealing up the shrouded area (mouth) pre exchangers, makes a HUGE difference on hwy temps providing everything else is in order
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Old 01-10-2008, 03:09 PM   #34
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I sealed up my opening to force air through mine and I have to agree. I didn't do any hard baseline or testing but I am guessing intake temps dropped 10+ degrees with more air being forced through the intercooler.

When you strap on a turbo, I believe that is in the near future for him. You will have an intercooler to feed as well so every little bit counts. The issue will most definitely be space so angles and shapes will become more important.

On a side note I'd be interested to see what the difference in under hood temp are with my cowl hood verses his extractor. Anyone have any science on that in here?

This is a good topic and some big brains on here.
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Old 01-10-2008, 03:16 PM   #35
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the purpose of the extractor is for engine cooling, not engine bay cooling. im sure yours does a better job cooling the engine bay, but his does a better job creating a more efficient cooling system, where your's adversely effects it.
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Old 01-10-2008, 03:24 PM   #36
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So your saying a cowl actually hood decreases cooling? Whats your logic? I am also going on the assumption that your statement of the cowl hood adversely affecting the cooling is even over stock hoods.
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Old 01-10-2008, 03:32 PM   #37
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/\ +1

I just picked a piece of lexan up at home depot a little while ago for another project that got shoved in the back of the line and had it laying around, decided it was good enough for this duty thanks to information provided by Loki...

I will run this setup as is (plus seal) for now, if any problems pop up i will redo it...
if i can figure out a way how to get my hands on some big ABS pieces for cheap i will try the other design at a later time or i just may attempt it with lexan and a heat gun, we'll see
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Old 01-10-2008, 03:35 PM   #38
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Quote:
Originally Posted by borkap View Post
So your saying a cowl actually hood decreases cooling? Whats your logic? I am also going on the assumption that your statement of the cowl hood adversely affecting the cooling is even over stock hoods.

an open cowl increases the under hood pressures, therefore decreases the airflow through the radiator.

an extractor hood promotes flow through the radiator, by creating a super-low pressure zone behind it.


thus forth, an extractor does better for the cooling system (important) and a cowl cools the engine bay (who cares)
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Old 01-10-2008, 03:41 PM   #39
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interesting, i never looked at it that way

question: if you are using a completely sealed shroud does the underhood pressure account for anything at all? I would assume it does when fans are not on, but once the fans come on, does it make a difference.
Also, isnt a cowl hood an extractor hood in a way?
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Old 01-10-2008, 03:46 PM   #40
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I think even a cowl will indirectly help cool the engine when sitting in traffic by reducing the amount of radiant heat the rad is exposed to before the fans come on. But the extractor does both, and the cowl works against the desire (of most) at speed.
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