shrouding and fan config help

assuming there are no holes in it after i get a barb soldered back on [i broke the solder joint pulling it out of the truck], i got the heatercore that i'm planning on using in my water loop today. came out of an 80's mazda compact pickup, copper fins even
it will be a good size to fit in my case the way i'm planning, however the size is a little off for an easy setup of fans: the finned area is 6.25" square, which comes out to about 158mm. it's 1 7/8" thick, but that isn't so important right now.
from what i can think of, i have 2 options to get a decent amount of air through the core: 4x80mm fans undervolted [shroud optional at this point], or 1x120 high-perf fan [shroud necessary to push or pull air through all the finned area].
4x80mm really isn't all that attractive an idea: at full power, it will be very loud and only be moving about 120cfm. at 7v, noise would be tolerable but cfm drops to about 72, and the pressure is a bit weak*.
[*this is based on fans i currently have, so it could easily change.]
an undervolted 120mm is better for noise of course. but to match the cfm of even the undervolted 4x80 setup, i would need a pretty powerful fan. this would still be pretty loud.
i will not push/pull with 8x80mm fans undervolted. just seems a bit ridiculous to me. push/pull with 2x120s would be ok, but i'm not too sure how effective the whole push/pull setup is. it doesn't make sense to me how 2 identical fans can move more air that way. if someone can explain this and/or show me some of their temps in push/pull, and push or pull setups, i'd be grateful. also, if there are other options i'm not thinking of, let me know that too.

note: since it was free and this is my first watercooling project, i would prefer to keep this heatercore to keep things cheap[er] and simple. i know it will not perform as well as a 2x120 rad.

pejsaboy said:

note: since it was free and this is my first watercooling project, i would prefer to keep this heatercore to keep things cheap[er] and simple. i know it will not perform as well as a 2x120 rad.

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Actually, it might work better than some 2x120 radiators--it all depends on the actual hardware being used. That said:

You will need a shroud to get the most out of the core. The idea is to pull (or push) the air through the unit, and that implies that you've got some type of seal between the fan and the fins. Since the core is so much larger than a fan you'll need a shroud to make sure the air is coming through the core and not from the sides. If you made a shroud that looked something like the one Thermochill makes for the PA-160 you should do fine.

And, I'd use a single 120mm fan in a pull configuration. Pull is generally slightly better than push, though push/pull is slightly better than pull alone but it'll cost you in additional noise and space requirements and for an extra degree or two probably isn't worth the effort. A good 38mm thick Sanyo Denki, Delta, Panaflo (in no particular order) undervolted should give excellent performance without making too much noise.

As for testing results of different configurations, pull/push/shroud/no shroud, here's a link to Phaestus' results showing the relative differences of the configurations.

Why not try both? Carboard and duct tape are cheaply available and function fantasticly for making quality shrouds. Just cut yourself a box with 4 flaps and tape it all together.
If you have 4 low flow 80mm fans, that might work better because you have 4 fans running faster than a single 120. pressure from those 80mm fans might be better, and you will get a more even flow of air through your rad. Definatly do a pull configuration. that works best on radiators from everything i have read.
The noise shouldnt pose a big problem since the inlet is the noisiest, and you have the shroud + your radiator to damp that noise.

push pull works slightly better, because it's hard for a fan to get air through the fins

pretend you're pushing a heavy box, and a clone helps you pull it

wow it's late, that's a horrible example

IIRC push/pull was indeed best but the advantage over pull alone was negligable.

citronym said:

IIRC push/pull was indeed best but the advantage over pull alone was negligable.

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Yes you are 100% correct.

thanks for the replies so far guys!
when setting up a shroud, how far from the rad should the closer edge of the fan be? i would guess the farther the better [to a point, diminishing returns], but its probably another one of those [many] things where it's a try it and see, right?
i wouldn't be opposed to trying a 4x80mm to test the differences in sound and cooling capacity, but i don't have 4 spare 80s laying around anymore. i suppose i could temporarily remove a couple case fans.... we'll see though
oh, and techun: that analogy made perfect sense. i'll definitely use a push pull if i can afford to buy 2 high end 120s at the same time, haha! i'm not gonna skimp in that department though- i'd rather have 1 awesome fan than 2 'decent' fans.

pejsaboy said:

... i'll definitely use a push pull if i can afford to buy 2 high end 120s at the same time, haha! i'm not gonna skimp in that department though- i'd rather have 1 awesome fan than 2 'decent' fans.

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Fans aren't that expensive, but if it becomes a problem shoot me a PM. I've still got over a case of Sanyo Denki 109R12121011s and I could part with a couple for a good cause

MVC said:

Fans aren't that expensive, but if it becomes a problem shoot me a PM. I've still got over a case of Sanyo Denki 109R12121011s and I could part with a couple for a good cause

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ah, appreciate the offer. i was just funnin' on the price of the fans though: you can find cheapies for $4-5, but a nice panaflo or delta could run up over $20 a piece [depending on the model]. besides, the project is going to come together over a couple months as it is. i've got some time before i need the fans

pejsaboy said:

ah, appreciate the offer. i was just funnin' on the price of the fans though: you can find cheapies for $4-5, but a nice panaflo or delta could run up over $20 a piece [depending on the model]. besides, the project is going to come together over a couple months as it is. i've got some time before i need the fans

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No problem. FWIW, the Sanyo Denkis regularly go for about $10 each, but there was a guy selling them on ebay last summer for around $60 a case ($3 a fan) and I bought a few cases

wow, can't beat that! i'll have to remember to check ebay for stuff like that. i always neglect to think of it for some reason....