For maximum airflow, you want the largest air cleaner element or assembly that fits the limits of the engine or engine compartment. One of the benefits of a high flow air filter is that unlike normal filters, it doesn't need to be changed every year. All you have to do is clean it approximately every two years. This is because they don't clog as quickly or as easily, but they offer better airflow and better filtration of the air entering the engine.
And if your engine gets more air, then it can perform better. In fact, a high flow air filter can increase your horsepower by about 3 to 5 HP and also increase your torque. At the same time, this can lead to higher fuel efficiency. How? In some of the more expensive units, the filter comes with a cold air intake unit. It is installed to extract air from the outside of the car instead of the hot air used inside the engine compartment.
Going back to science class, cold air is denser and therefore will burn better, thus improving your engine performance. Thick air filters may automatically seem like the best option. Thicker means more filtration, right? In most situations, that's the case. Thicker air filters tend to last longer because they have more square feet to capture and retain air particles. To put it into perspective, a 1-inch air filter may need to be changed every month, while a 4-inch air filter can last up to six months.
At the same time, a thicker filter is less restrictive and will allow for better flow of purified air. Reducing the thickness by one inch shouldn't be a big deal; for example, you should be able to use a 4-inch filter instead of a 5-inch filter. When a large filter, such as an ultimate air cleaner, is installed, it captures and removes particles or contaminants that adhere to the equipment and breaks down all of these contaminants in the air and on surfaces anywhere the air conditioner is applied, making the air much cleaner. The air intake filter is responsible for keeping dirt and debris out of the engine, and a larger filter will obviously do a better job than a smaller one. If the filter were AFTER the turbo, then the volume flow would be lower for the forced induction configuration. If you try to use a 4-inch thick air filter for a system that is made for a 1-inch thick filter, the efficiency will be worse. It's a lot like a vacuum cleaner, when you notice a decrease in power; a dirty filter can be the cause because the air is literally pushed at the price of your vehicle's energy.
So, if it fits your oven, then a 4-inch air cleaner is better than a 1-inch air cleaner when it comes to improving air quality. The guys at Engine Masters tested all kinds of air filters and what they found in a different scenario (domestic v8 with carburettor) is that turbulence in the filter has more of an effect on performance than anything else. I had a table that listed the minimum size your filter should have for a given hp for the NA and turbo engines, I will post it if I can find it. Ovens come in a variety of sizes and configurations, which means there's no one-size-fits-all filter. When performing routine maintenance on your vehicle, one of the most overlooked aspects is the air filter. However, the difference in performance between a small and a large filter is usually negligible, and it is more important to ensure that the filter is clean and unobstructed than to worry about its size.
I currently have a SUPER DIRTY K&N air filter that is placed in front of my radiator through custom pipes. Deeper depth can also improve filter life and efficiency; they also make it easier for air to enter and exit the filter. When it comes to choosing an air filter, size does matter! A larger size will provide better filtration and improved performance for your vehicle. It will also last longer than smaller filters due to its increased surface area.
However, make sure that you choose one that fits your vehicle properly; otherwise you may end up with decreased performance or even damage to your engine.