Do K&N air filters make any difference? This is the million-dollar question, and it all comes down to the type of car you have. K&N filters offer increased airflow, which can potentially increase engine performance, but only if the car is able to take advantage of it. Most cars are not able to do this, and the increased airflow can actually make them more prone to build up debris and dirt. Tests and research papers have confirmed that people have reported a decline in performance and an increase in fuel consumption once they replaced the original filters with K&N filters.
The effect of these filters on normal cars is not worth the added risk they pose to the engine. K&N filters only seem to make a noticeable difference in more performance-oriented cars and perform best in the clean environment of a racetrack. In fact, Fenske tested filters in a real environment, testing acceleration times between four candidates. The K&N filter came out at the top, producing a 2-3 percent improvement in acceleration time compared to the unit. However, no matter how much airflow is increased, it won't make your jetta come out any faster with an air filter. The biggest gains come from installing a complete cold air intake system.
While replacing only the OEM air filter with a K&N high flow filter will add power and increase acceleration, it won't be anything significant. People have also reported an increase in fuel consumption once they replaced their original filters with K&N filters. It's important to be delicate when polishing with a buffer to avoid leaving marks or scratches on the car body. The steps involved are as follows: shock absorbers must be designed specifically for cars as most shock absorbers designed for other surfaces rotate at higher RPM, which can leave swirl marks and even damage the paint layer. More air equals more power, and oversized K&N high-flow filters will allow for greater airflow. While I've never been the type of person who especially stressed about getting all the possible energy gains out of my car (when I had one), I've always been skeptical that a high-performance air filter would have any significant difference from a standard one.
But if you do some basic tests, it seems that I was wrong. The amount of released horsepower you'll get from an air cleaner drop is negligible. In effect, this means that an engine requires almost fifteen times more air than fuel for efficient combustion, which emphasizes the importance of providing a high volume of air through an intake system. Fuel injectors provide a precise amount of fuel, which is combined with the air supplied by the air intake system. The trademarked red filter (usually conical in shape) on display or its kit may include a closed air box. Most disposable paper filters create a great deal of airflow restriction, as the openings in the filter media must be extremely small to filter efficiently, which slows down airflow. K&N high-performance air intake systems are designed to create a more aerodynamic path for airflow to the engine by removing the original intake pipe, which can create excessive turbulence, and also by using highly efficient airflow filter media.
An air filter helps seat the air more evenly instead of the air hitting the AF sensor in large chunks, which obviously makes the fuel supply more uniform. The filter can be very effective in blocking these impurities, but that would also slow down the airflow, which could mean that the engine will not tire of it. Most dry disposable paper air filters work according to size, dirt particles that are larger than the openings in the filter media are trapped, while particles that are smaller than the openings pass through them. The filter could be made more porous, which will allow more air to enter, but it will also allow smaller impurities to enter. Yes, aftermarket air filters work but don't expect lots of extra ponies to suddenly appear when you hit the accelerator. In conclusion, K&N filters offer increased airflow and potential engine performance increases for performance-oriented cars on racetracks. However, they can seriously hinder cars if driven in heavy traffic where there is a lot of suspended particles in the air.
They can also lead to decreased performance and increased fuel consumption for normal cars. It's much cheaper and easier to replace an air cleaner instead of an entire engine block.