[Bob with the 66]

Originally Posted by lust4speed

Smittyseng, K&N also said that 1/8" top and bottom (1/4" total) should be subtracted for the base material coming up into the filter medium. So 3" becomes an effective 2-3/4" high filter.

Can anyone locate the fill-in-the-blanks screen on the K&N site that was there to help figure necessary filter size? I looked all over for it, but nothing. I remember that when I was doing my calculations on their site that a 3x14 round filter on a 455 (462) was okay until 6,200 RPM (121 square inches). Ran engine on dyno up to 6,500 RPM, and horsepower figures were the same with just the filter base plate in place or the K&N filter and top on also. We lost 10 horsepower when the filter was completely removed.

When I was running the dual quads on the 428 (437), I had calculated out that they would get enough air if I used an 8x12x2-1/2 (141 sq. in.) K&N filter on each carb. Ran on the chassis dyno down at Harry K's, and made a run with the cleaners off and lost 8 horsepower. So in two tests, the old K&N computer was accurate, and even a little conservative on sizing.

Please confirm, are you saying that your results showed a 8 hp losss with no air cleaner or a 8 hp loss with the KN air filter. I am very interested in this post because I run the KN 9" v-stacks on my dual quads. What about running there 5" filter instead of the 3" filter, has this been tested?