Nice tests, that is some pretty good info. For ver.1 vs. ver 2 where is water going in and out. I assume it goes in the red arrow and come out the blue one. BTW as a Web/Graphic Designer I have to say... nice diagrams. Good idea with the air break too. My only criticism... Results 3 is misspelled .

I am really surprised just how big a gap there is between 800rpm and 1200rpm. At 1200rpm there isn't much of a difference between stacked and unstacked and I bet at 1500rpm+ with higher pressure fans there will be no measruable difference between stacked an unstacked, in this setup.

Quote Originally Posted by SNiiPE_DoGG View Post
merely a result of using 1250 rpm fans with weak static pressure capability, sanaces are a different story
Yeah, I wonder how my Ultra Kaze at 3000rpm change the story.