Shroud design... Block vs Curved ??

Like the title suggests, I'm interested in everyones thoughts on curved surface shrouds (ala D-tek) vs Box shaped ones...

I have fussed with the idea for years but don't have the skills to make a nice one myself.. My brother suggested a plexi box.

Some points I'd like to cover.

Plexi vs cardboard. Noise factor ?
Cost of Plexi - cheap ?
Mounting ideas. (neoprene on outer edges?)

Thoughts ??

I think performance wise they're all about the same, wheter boxy or curved. I have found that cardboard is slightly quieter than plexi and metal shrouds, probably because of the dead air spaces. Neoprene or something similar to weather stripping on the outside edges works well, since it seals the air gaps and kills some vibrations.

I'm in the process of re-designing my shroud system right now. I think there is less importance in whether the shroud is tapered as there is in how far away from the actual radiator fins that the fans are. I can say beyond a shadow of a doubt that if you can place the fans 1 inch away from the radiator fins, the setup is a lot more quiet than if the fan is only 1/2 inch away. The worst scenario for noise is screwing or cable ty'ing the fan right up against the fins. A shroud is a mult-function device. It needs to provide a way to retain the fan, align it with the radiator, provide a means for spacing the fan from the radiator and prevent the air from leaking around the radiator. Shroud material is a factor that also impacts noise re-radiation. If the material is too thin, it will act like a drum head and propagate the noise. If the material is not dense enough, the noise will simply pass right on through it. That, having been said, I'd say plexiglas would be superior to cardboard for both reasons. It is less tympanic and more dense.

Looking at some of the plexiglas designs, I am tempted to make one consisting of three distinct compartments. One on each end to slide the fans down into and one in the middle to slide the core down into. Emphasis would be placed upon ease of insertion and extraction of the three components and close tolerance fit to prevent air leakage and rattling. My preoccupation with the compartment approach is for the sake of performing preventive maintenance on a regula basis. It amazes me how much dust I can dislodge with my air compressor each month, yet I know I could remove even more dust if I could simple remove each component from the mount and clean it individually. Compartmentalizing would also lend well to experimenting with different fans or modding the core/barb assembly. My sheet metal shrouds are semi-permanently attached to my core right now and it would be a major headache to have to remove any one component. Luckily, I use a case that has room for the increased assembly size that would result from making a plexiglas system using 1/4 inch thick plexiglas. More as I get closer to implementing.

Hoot

Think of a wind tunnel.....smooth transitions are always better. But the truth is, we're not trying to lift an airplane, so it affects us less. How close you want to be to the ultimate condition is up to you.

I had great luck making a shroud formed out of 1/8" red transparent plexiglass. It tapers from the radiator to the front case intake where a pair of 80mm fans are. The trick is that it also fits a 120mm fan half-way to the radiator (an inch from the radiator's face). I found the single 120mm fans outperforms the pair of 80mm fans.

You can see it here

Thanks for the input guys, that's a lot of good info Hoot and an interesting idea.

Right now my shroud put's my 120 about 3.5 inches off my radiator - which I feel is a bit far. The shroud is make of cut up cardboard and has a very heavy seal of duct tape holding it to the radiators and sealing the edges - etc..

It's actually quite nice and quiet but I feel it could be quieter. Admittedly even with my fan turned all the way up it's not as loud as the damn OTES system on my GF4.. but when I get rid of that I want the rest of the system to remain quiet as well...


Is plexi easy to work with ?? I will most likely be using a dremel to do any cutting. Is there an optimal thickness ? (personally I would like something thick, and not -too- flimsy) and how expensive might that be ?

Also having a dumb moment here, but what exactly does "Tapered" mean ?? If I actually manage to get it built mounting it will definitely be an issue. Would it be feasible (with the right thickness) to bore some small holes into the sides of the shroud itself (that is, the "thickness" of the plexi pieces) where the shroud meets the radiator, and simply insert a bolt into it ? I would think with a wing-nutt or something on the end it would hold properly.

Also, what do you think about layering the plexi pieces themselves with neoprene as opposed to just the gaps where the pieces meet ?

Dust and cleaning won't be an issue for me, as I will most likely have it positioned in the case and only shourded on one side, so Ican just stick a dust buster up to it. I might also rig up and air filter of sorts between the shroud and the case if possible and it won't harm my cooling/noise potential


Any suggestions would be great.

Here's another (potentially stupid) idea I picked up at OCAU:

Put a cone on the fan, to compensate for the lack of airflow in the center: it might help redistribute the flow more evenly.

Here is some pictures of a couple of shrouds I've made from plexi just to give you some ideas. I'm still working on my plexi skills.

Plexi-shroud1



Plexi-shroud2

Blackhawk

wow thats weird.....Elite has used blackhawk in like every forum and in cs/ut2k3/bf1942/mohaa .....LAF!

I remember seeing that second one before.. I must say I could never build anything that good, haha... Guess it'll take a few bucks to find out

I like the angle stock reinforcement in the one picture, but then I tend to over-build on strength. I plan on joining plexiglas junctions with clear RTV / Silastic / Silicone Rubber, call it what you want, adhesive. Besides being a good adhesive, the natural deadening effect of the soft rubber will help dampen vibration in the larger flat surfaces. I'm not too concerned over whether it is "Pretty" as I'm not into "Window Dressing" my PC.

As far as a forcing cone goes, I'm not too keen on the idea because it imparts additional resistance to the airflow and axial fans are notorious for not tolerating resistance to airflow.

As far as having too great of a distance from the fan to the radiator goes, I don't believe there is such a thing as long as the channel is relatively airtight.

I have worked with both Lexan and Plexiglas and so far have come up on the lucky end of the equation. Depending upon the size of the sheet I am working with, on larger sheets I use my table saw to cut it. Just pay attention to the sharpness of the blade and your feed rate. You don't want to rush the cut and wind up melting the stuff. Then it gets as ornery as hot pizza cheese. For smaller sheets, I score both sides and break it on a sharp edged, flat surface. Most hardware stores that cut glass for windows can also cut you Lexan or Plexiglas for you. They usually have a neat score and break machine. If they happen to sell the stuff, buy it from them. That way, if they hose it up, its their problem.

Hoot

Around how much does 1/4" plexi cost per sq foot?

Lithan said:

Around how much does 1/4" plexi cost per sq foot?

Click to expand...

Go to your local hardware store or a Home Depot. My local shop gave me a nice sized scrap for $2. I think a decent sized piece at home depot is roughly $8. Pieces 24x48 are $30. Here is what I built from the leftovers of my Acrylic rig.

The shroud is constructed of 3 pieces. The main piece I formed with a heat gun. The top and bottom pieces were glued into place with superglue. Dissolvent cement is a better choice for bonding the pieces but I ran out prior to construction. I used clear Dow corning to seal off the fan and heater core matting surfaces. This way I made sure not 1 molecule of air would escape from passing through the heater core. The core is from and 86 chevette and the fan is a Comair Rotron 172mm Major. The fan sits 1" from the core. I might have tried 1.5" or so but saving .5" was more of a concern with the tiny case.

A curved shroud is ideal for max airflow but practically speaking you wont notice a difference. Fan spacing is very important but I don't have data to conclude what perfect spacing would be. As long as the shroud makes a good seal around the core and fan you should be fine.

That's some great info there, thanks guys.

Are those deeper 120's more epensive than the run of the mill thin ones ?? likewise how does the noise work out ?

Lithan said:

Around how much does 1/4" plexi cost per sq foot?

Click to expand...

At my local plexi place I pay $35 with tax for a 2' x 4' sheet of acrylic plexiglass.

blckhawk

Wow this stuff is starting to sound expensive...

Maybe I should.... "refine" my cardboard skills, or at least try to make something out of wood....roofle to that..

Neco said:

Wow this stuff is starting to sound expensive...

Maybe I should.... "refine" my cardboard skills, or at least try to make something out of wood....roofle to that..

Click to expand...

That just what size I buy because I make my cases from it to. You know how many shrouds I could make from that one 2' x 4' sheet?
I shudder to think!

blckhawk

Personally I like the brass approach. This shroud is made of 1/16" brass stock. With my newly designed heater core arrangement, cleaning the core/shrouds/fans is not a problem. Air comes in one side out the other. No more dust inside the case from the 120mm fans. This is a BIG plus. To clean one only needs to blow air from both sides into the core.

Check this link. You might find it interesting .

Bob

Great link Bob. Thanks

Hoot

Haha... Well guys my brand new case came today and I didn't even have to pull out the tape measure to tell myself there is no way in hell I am getting a heatore core (at least the one I own) inside of it the way I wanted; guess it really was a 35 dollar case (but its 2 feet tall and thats what I wanted) Kind of a let down to be honest.

Also kind of a relief, cause it makes it all that much easier for me to buy a Black ice radiator or something next month when my friend pays up.

That's a very nice setup there Dodge viper, and I was considering a similar arrangement but don't have the skills/tools to pull something like that off.. or the money to waste trying
Heck I doubt the core would fit in this case properly anyhow so maybe it's a lost cause



Also.. can someone tell me what's on that link ?? I hate registering at forums just to read a post.