Quote:
Originally Posted by Captain Snooze
There are two aspects to filters: flow and filtration. Yes, it is possible to get better flow along with decent/same levels filtration but most aftermarket filters I've seen emphasise flow (more hp) over filtration. (Because compromise.) The testing procedure for filtering is quite extensive and most people don't seem to consider filtering, just the supposed hp gains. Is the difference in filtering significant? I have no idea. Maybe it would take 200,000 kms to find out. It is just something else to consider.
Myself? I change my oem air filter about every 10,000 kms regardless. *shrug*
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A third dimension is dirt capacity. As filters get dirty, they flow less air. A filter with a higher dirt capacity will flow more consistently over its maintenance interval. A lot of performance filters are like this: they flow very well flow very well when they're clean, but worse than OEM when they're dirty.
This link has some data and analysis from an ISO 5011 test comparing an OEM-style filter to various performance filters.
http://nicoclub.com/archives/kn-vs-oem-filter.html