Quote:
Originally Posted by lust4speed
Except K&N has taken the folds into account with their stated flow rating of 6CFM per square inch of (exterior) filter medium.
Using the 6CFM figure, my 121 square inch sized round filter would flow 783CFM -- which wouldn't be enough to satisfy the needed 829CFM requirement of the 462 at 6,200 RPM. Since we proved on the dyno that the filter size was sufficient up to 6,500 RPM, I'd say that their estimate is somewhat conservative. That nice even 6CFM number was probably rounded down. I'd say that it would be entirely safe to use the 6CFM figure for figuring minimum filter size.
I avoided splitting hairs and simply installed a 5x14 K&N filter on the drag car. Probably didn't need it, but had the room so why not?
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Remember though too, if a air filter will flow 783 cfm at a given vacuum like 1.5" or so (haven't found a EXACT number anyone will admit to) that it CAN and WILL flow more BUT it will create a vacuum inside the air cleaner affecting the tune of the carb AND it will reach a point where it goes from being a slight restriction to a terrible resriction, Smitty