Is this right? Running a fan at lower rpms...

[swtguy]

I'm curious if I was to hook up the tornado to a fan controller and run it at lower rpms how much cfm would it put out. Can I divide the rpms by cfms and use this ratio to find out or does it not work like that? It runs at 4800 rpms and moves 119cfm so I was thinking if I ran it at say 3800 rpms it still should move more air than the 50cfm my current fan does(by my calculations 94cfm) and not be much louder....

[gar187er]

i dont believe its a straight ratio...it gets lesser cfm gains as rpms increase....cant say i took much applied physics... :rolleyes2

[kane2g]

going from my knowledge of turbo's, its not a ratio, its more of a curve. @ some point its going to be most efficient and no matter how many RPMs you would add, it wouldnt push any more air through, same goes for lowering the RPMs, @ certain point its not going to be pushing any decent amount.

Going with bigger fans 92 or 120mm is best choice, as they get same CFM @ Lower RPM.

[gar187er]

curve...yea thats it....got i was brain dead when i was writing that

[swtguy]

Yeh i have an enermax 92mm fan on there right not that blows about 50cfm but was wondering if running a tornado at lower rpms would get more more cfm than my current fan. The biggest fan my slk900a will fit is92mm so 120mm isn't an option.