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Okay, n00b physics/engineering question coming up.

I bought a new air filter on the wkend (long overdue), replaced the existing Ryco from the po to a cheapie, Wesfil/Cooper, in my stock airbox. Noticed it has exactly half the number of "folds" (38 v 76).

Does that mean there is reduced air flow through the Wesfil filter because there is less folds? Does more folds = more surface area = improved flow?

One thing I am sure of is this, there is more air flow through a new 38-fold filter than through a dirty 76-fold one. Noticed slightly improved performance instantly, it even sounds different.

Cheers

If I remember correctly the difference between running a stock filter, and no filter, was only a few % increase in power (when using no filter... which is zero filter restriction)

http://autospeed.com/cms/title_Into-the ... ticle.html
Not the test I'm remembering, but the same website.
It suggests about 3%



So if OEM filter VS no filter is only a 3% difference, then one would expect OEM filter vs other brand to be such a small change it wouldn't be worth bothering with.

FWIW from a physics perspective,
more surface area = improved flow, all else being equal.

this assumes the same level of restriction of both filter mediums, which is unlikely, unless both filters use the same filtration medium.

but yea, real world difference is pretty much zero. however, more noise = more fun.

half the surface area means it will get dirty twice as quick.

it will flow all the same.

project.r.racing wrote:half the surface area means it will get dirty twice as quick.

Understandable, but I figured at less than half the price it was better value.

Anybody have recommendations for good filters in the stock airbox for NA8? or NA6 for that matter? Pretty sure it's the same box.

if it is half the value, then replace it twice as much. problem solved.

or ryco.

Yes, believe it or not I had come to that very conclusion on my own..