A shroud keeps the fan slightly away from the rad and directs all the air onto the rad. It eliminates the dead spot, due to the hub in the centre of the fan. It also makes the flow uniform all over the rad. Its just a cone (or cylinder) that cut half way so that the fan is on one end and rad on the other.
You can be ghetto and make one out of cardboard, alunminum or plastic or anything that u find lying around. Or be chicken and buy one. Search around in google, there are many articles and ghetto mods in forums that will guide you.
I will tell you again that a heatercore is waay better than a rad. Let me know if you want one.
Oh so u are using another pump...How many watts is that pump - 18m, 2800rpm? Its inline or submersible?? If its more than 50W and submersible then its not worth it at all! The heat it adds to the water is not worth the extra flow rate. Im not very sure abt the pump with the kit but it seems a bit weak at 4.8W. Thermaltake dont have all that good a reputation either. Something like 10W would be ideal. But i guess its ok for now.
As for the fan on the rad, get the fan with the most cfm. Size doesnt matter as you can make a shroud to fit it nicely! A high cfm 120mm fan will be good. One pulling and one pushing if u are getting fans that arent so powerful.
Raghu.
