When it comes to your car, the air filter is the first line of defense against dirt, dust, and other debris that can cause costly repairs. But does it really matter what type of air filter you use? The answer is yes! A higher quality air filter can contribute to higher engine efficiency, longer engine life, optimal airflow, maximum engine performance, and best fuel efficiency. The Stack Exchange network consists of 180 communities from Q26A, including Stack Overflow, the largest and most trusted online community for developers to learn, share their knowledge and develop their careers.
Air filters
are essential for keeping your engine clean and running smoothly.But unless you're the princess who slept in the pea, you won't notice the difference between a standard paper filter and a premium one. You may get about 1BHP more from a good quality filter, but what they really do is take longer to clog. So, they don't really GIVE you more power, they're better at AVOIDING energy loss once you've driven a couple of thousand miles. It depends on the application.
I paid good money for a K&N air filter for my old traveler, an 18-year-old Subaru 4-cylinder. After installation, I heard a pretty clean grunt noise from the engine when accelerating, but the idle and mileage and gasoline performance were the same. On the other hand, a K&N air filter installed on my Kawasaki Concours not only gave me that cold grunt noise when accelerating, but I noticed a smoother idle and a small increase in top speed performance above 7,000 rpm. So there you go, I think they're worth the money and time spent cleaning them every few thousand miles if used in a performance application, but for a normal old car, the standard paper filter is the way to go.
With decades of combined experience covering the latest news, reviewing the best equipment and advising you on your next car purchase, The Drive is the leading authority on everything automotive. The Drive and its partners may earn a commission if you purchase a product through one of our links. Take a look at our picks of best-performing air filters for cars to help keep your engine clean and running smoothly. As my audiologist can confirm, I have spent much of my career alongside noisy cars that run on chassis dynamometers. Air intake modifications are a favorite in the tuning industry, so I've tried every variety you can imagine; from simple filters to polished aluminum cold air induction kits, to custom-made carbon fiber airboxes. So I have a good idea of what works and what doesn't stop performance. If everything works as it should, there is no metal-to-metal contact during normal operation.
Bearing surfaces have a thin layer of oil between them; the minimum expected is just over 5 microns. When this is true, particles below 5 microns cannot be trapped between two surfaces causing damage to the surface. However, as oil viscosities become thinner and thinner, tolerances tighten and engines turn faster or use higher cylinder pressure than ever before; the latest data indicate that many oil film thicknesses are regularly in the 2 to 3 micron range. Air filters stop particles in three different ways. The first and most obvious is impaction; this is when the inertia of the particle takes it to the individual elements of the filter medium and stops it as if it were paste in a strainer.
The second is interception; here you have a particle that is small enough to be directed with the air stream and would normally pass through the middle but it passes close enough to stick to it. Obviously this captures smaller particles than the holes in the filter are designed for but only a certain amount will get close enough to stick together. The third measure is diffusion; this is for particles so small that they move in zigzagging patterns known as Brownian Motion. Similar to interception particles that are so small that they would never be captured by impact would hit the filter media and stick together. If there is no mechanism to cause the particle to adhere to the medium such as in an oiled filter; then movement of particles interrupted by interception and diffusion can be slowed but not stopped. The second measure of an air cleaner which is of most interest to aftermarket tuners is flow. Vehicle manufacturers design airboxes so that more than enough air flows to supply the engine under all circumstances.
Tuners will make you believe that engineers are incompetent or have some nefarious plan to limit power of your car but neither is true. I've seen some surprising claims of power gains from modified air filters and induction systems; while you can gain one or two horsepower at very specific RPMs they never give power across range. In summary take filtration claims with grain of salt grain less than 5 microns in diameter. What companies advertise could be best case scenario with filter loaded and only tested with ideal particle size then take flow rates and power gains with entire salt shaker. Flow rates rarely occur with pressure and density contributing those numbers. Data shows greased filters are likely trap more smaller particles than dry filters but are those particles so small that they won't cause damage anyway? Oil has been used trap dust in air filters for almost entire time internal combustion engines have existed. K&N was first popularize use of oiled cotton in 1960s unlike oil bath method invented decades earlier K&N cotton medium other brands most popular but greased foam also common. Experimental data have shown these types of filters offer greater efficiency for smaller particles since lack better term they are sticky. That filtering efficiency present from installation.
