Need shroud building help...

I have heard that there is an optimal distance from the HC/rad that a fan should be placed.If thats true, then I need to know if I should mount the fan on the inside or outside of the shroud for the best efficiency.Then I would need a basic blueprint to guide me.I could do all the calculations myself, but if there is a quality blueprint I can reference, why not use someone elses calculations?I thought I had seen a DIY shroud building guide somewhere.I think it was here, but all other input would be appreciated---especially about where to mount the fan and the best distance the fan should be from the heater core.

Thanks!

in my experience, mounting the fans directly to the radiator\inside the shroud, had the best effect as the air maintains its speed and blows through more quickly. in a pull system, it also sucks more air directly from the gap, the exception being if you're able to seal around the shroud and fans to create a real vacuum effect which would maximize airflow.

http://www.ocforums.com/showthread.php?t=452278
here's a shroud that you could try out with both configuration, dimensions are included so you could use those for your specs. enjoy!

Im sure there is any number of viable math to calculate this, but its really dependant on what fan you use i would think since they all have slightly different airflow characteristics.
Hey, kinda like airfoils =D

I generally like to keep my fans no more or less than 3 cm or 1 inch suspended from the heatercore, and 1 fan for every 160cm square of cooling space. this way, you get pretty even airflow across the entire rad in a pull configuration.

I also like to mount my fans OUTSIDE the shroud. it would take up less space to have it inside, but not really. you would have to make the shroud bigger to have enough realestate to house the fan too.

Im sure tapered shrouds work best, but i like to keep things simple and clean. I also, dont have a lot of tools or workspace to play with metal/plastics, so i use matboard or various other paper products and industrial adhesive film to adhere everyhing.
Simply, Cardboard and ductape. gotta love it.



Just cut, fold, tape, and your done. suprisingly, it seals really well =O

I have plenty of aluminum sheet metal to try different designs with.I'd say the sroud will cover an area thats about 7.25" x 10.5", and the smallest piece of sheet metal they sold was like 18"x36".I want to do a good job because I dont know if the shroud is going to have to be part of the exterior viewable part of the case.I was mostly concenred with the rumor I heard about the fan being placed a certain distance from teh heater core/radiator for optimal cooling.I think I saw an article that said it was best if the fan was something like 1.14" from the surface to be cooled.My logic tells me that mounting the fan with little or no distance from the HC would cool the best because of the restriction the HC creates by design.Is there a recommended distance the fan should be placed from the HC, or it that just a rumor without factual value?

Like I said, if you seal it, put it further away, if the fan is blowing, put it flush, if it's pulling put it very close to flush like 1/4", if it's push-pull, put them both flush.

The only really good thing about a shroud as far as cooling is the easy of sealing the airflow path so that nothing bleeds out or is sucked in from the side rather than through the radiator. There will always be the benefit of having directed airflow.

But if your going to have fans blowing right on the radiator with a shroud, you want them flush or the air will just blow across teh radiator and loop, since it cant excape thanks to the shroud. The opposite is true if they're pulling air through, you want it spaced so it has room to create a negative pressure taht will pull more air overall then the negative pressure created if it were flush: this is because the air currents generated by the fan are still very circular when its flush and that doesn't work well for pulling. for blowing it doesnt matter much because the warm air that gets inbetween the fins naturally creates negative pressure as it becoems less dense and is pushed out be the onslaught of denser air from the fan.

so either follow the dang instructions or dont, it's really muchado about nothing, just dont have ur pulling fans flush with the radiator and your purshing fans spaced out from the radiator.