A filter’s a filter, right? Wrong. There are a several different filter materials available, and like most things in life, there’s a trade-off with each type and no clear winner. So, before you buy, it’s very handy to understand the pros and cons of each filter material.
Almost all production air filters are made from paper, which is very cheap and gives great filtration, stopping even the smallest dirt particles from reaching your engine. Unfortunately, it’s the poorest flowing for any given size of all filter types, and being made of paper, it’s a throw away item – unlike aftermarket filters, it’s not possible to properly clean a paper filter.
If we had to say there was a ‘winner’, cotton filter material would probably be it. It has much better flow than paper, and is fully washable too, making it a good all-rounder, and it’s the filter material of choice for most race cars. Having said that, it may be better flowing than paper, but it’s not as good as our next two options…
The effectiveness of filtration and amount of flow of foam filters depends on the density and thickness of it, but overall, for any given size, it tends to flow a little better than cotton filters, albeit at the expense of a little filtration ability. A really thin foam filter with large gaps can flow massive amounts of air for its size, but its dirt retention ability will be questionable. Thankfully most top foam filter manufacturers have done extensive testing and produce filters with a great mix of flow and filtration.
These are arguably the coolest looking filters, and potentially the highest flowing too, but depending on the mesh size, their filtration ability can be quite poor. The tighter the mesh is, the better they filter dirt, but without making the mesh so fine that it’s actually a restriction, it’s always going to struggle to catch smaller dirt particles. When you consider even foam and cotton filters are usually fitted with an extra filter bag over the outside when used in particularly dusty areas, you should be extra careful with wire mesh filters; especially if the filter is mounted low in the front bumper.
Words Stav Photos various
See our Performance Car Air Filter Test