Originally Posted by Moonracer
we found that on a dyno the K&N filter cost 3 hp over a regular paper filter on our race car.
Was this with just a k&N filter or with an open intake?
I'm not doubting what you're saying, but isn't 3hp too small to attribute to one thing? I would believe it if you did 20 runs, did an average, then replaced the air filter with the K&N, did another 20 runs, took a new average, and found the 3hp loss. To me though, something like 3hp is so small that it's probably not statistically significant at all. I also wonder if a car would need a certain amount of time to "adapt" to any changes the air filter might cause. Interesting...