Thread: How Much/How big? Air cleaners.

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According to K&N, the motor needs 1 square inch of filter area for each 6 CFM of air into the motor. This is ACTUAL filter area and does not include the glue around the perimeter or other protuberances that might get in the way of the ACTUAL filtering medium.

If a 350 Chevy with short cam, short intake, small carb and cast iron exhaust manifolds passes 486 CFM @ 6000 RPM's @ 80% efficiency, then you would divide 486 by 6 and find that you would want 81 square inches of ACTUAL filter area. Some 14 x 2 filters that I have seen have only about 1 3/4 inches (or less) of ACTUAL filtering medium. If you multiply 14 times 3.14159 times 1.75, you find that such a filter has an ACTUAL filtering area of 77 square inches. So, theoretically, a 14 x 2 filter will not even feed a crummy little 350 Chevy making 80% efficiency. What to do? Glue two or more filter elements on top of each other and use a longer stud. You guys with a 100% 383 will definitely need a two-stacker.

What's that you say Bunkie???? No room under the hood???? No such thing, Dude. Fire up the Sawzall and MAKE room.

I don't even say anything any more to the ricers who show up at Firebird. Some time ago, one of them laid down some long green for a Fosdick intake air system that terminated with a K&N filter. Now, this fellow terminated the filter right behind the radiator core, the worst possible place to take in intake air on the entire car. (200+ degrees F.). Well, since then, every ricer who shows up has the same idiot arrangement. It's a case of monkey see, monkey do, without ever thinking through the consequences (the car slows down).