Do high performance air filters really make a difference? It's a question that has been asked for years, and the answer is yes. In fact, a high flow air filter can increase your horsepower by about 3 to 5 HP and also increase your torque, leading to higher fuel efficiency. While the numbers may be small, the effects are real and can be felt when you hit the accelerator. To understand why this is the case, it's important to understand how air filters work.
An air filter is the only thing that stands between the engine and the dirty air outside that tries to steal some of those important horses. Often chosen for off-road rallies and other motorsport activities, foam air filters have a higher filtration capacity than their aftermarket counterparts and can therefore flow stronger for longer. Used as an OEM filter in most cars, including the MINI, the paper air filter is simple in its effectiveness but lacks efficiency. Stainless steel air filters may look amazing under the hood, but their filtration properties are considerably lower compared to other aftermarket counterparts.
Cotton gauze air filters are the next most common type of air filter on the market, and since 1969 K&N has been bringing these filters to the aftermarket world. For air to flow through the filter, there must be a large number of microscopic holes in the filter, or the holes must be open enough for air to pass through. As a paper air filter picks up dirt, etc., it fills up and its filtration properties drop dramatically and therefore needs to be changed. Paper air filters are discarded and replaced, not only costing more money but creating more waste. In order to test how well aftermarket air filters work, Jason Fenske of Engineering Explained conducted some basic tests with dynamometers. He tested a dirty air filter, an identical clean filter, a cheap OEM alternative filter, and then a K&N performance filter.
The results showed that there was an increase in power with each aftermarket filter tested. Fuel economy was also improved because high-performance air filters draw air from outside the engine compartment, where the air is colder. The conclusion? While it depends on how well the standard intake system has been designed - one of the cars tested did not show significant power increases - there's no doubt that high-performance air filters can make a difference. Not only will they slightly increase your horsepower, but they will also improve your vehicle's fuel economy. Air filters are one of the easiest and quickest components to exchange for an aftermarket part, and many companies claim that their design will increase power, torque and improve acceleration.