Kayin
04-02-2007, 07:59 PM
As I get ready to fire up my new pump with its hand-cast top, I want to ask a chamber question. Didi you match the depth of the chamber exactly, or is it OK to have a larger chamber? Mine is a bit oversized, but I can easily reduce it by pouring in some more polycarb in the morning.
Also, is that lip type thingy that important? I remember the Radiical top sucked hardcore, and it was missing it, but the modded Alphacool was OK, and it was also missing it...
If I'm not mistaken, it's basically keeping the inlet on top and the chamber smooth that's the key to making this work, right?
Petra
04-03-2007, 07:34 AM
None of the aftermarket tops match the dimensions of the stock top exactly, as its geometry is a bit too complex to machine in a cost-effective manner. Anyway, keeping the depth as close to an approximation of stock as possible, since the stock top's impeller housing ceiling is slightly conical, should yield the best results (so, about 8mm). Using a larger chamber would likely have an adverse effect on performance.
As for the ring around the inlet, you really don't need it. In fact, I have removed this feature with the latest version of my top (the DDCT-01s) to allow for compatibility with the DDC-3 series pumps (blue impellered DDC). The keys to a good top are in the shape of the volute (impeller housing wall, ceiling, etc. -- all of the aftermarket tops need work in this regard, including my own), the size of the inlet (you tend to lose max. head pressure with a larger inlet), the size of the outlet, and the contour/shape of the outlet.
The poor performance from the Radiical top, for example, can almost entirely be attributed to its incredibly crude, and oversized, outlet.
I hope that helps :)
Kayin
04-03-2007, 08:14 AM
You answered my question perfectly.
I'm really glad for the help, I may can start assembling my loop today now...