K&N has published test results asserting that its oiled filters do not cause MAF sensor failures. However, there are several other common causes of damaged MAF sensors, including brake cleaner contamination, extremely dirty/contaminated filters, and loose battery terminals resulting in voltage spikes. Potential issues have been reported with oiled air filters on modern engines that use MAF sensors, which may stop working correctly when fouled by oil from an oiled-gauze air filter. Other 3rd-party testing noted that a K&N oiled filter increased horsepower over its OEM counterpart. However, air filters in general become more airflow-restrictive as they collect contaminants, but efficiency typically increases for the majority of a filter’s service life. K&N's claims for their air filters have been the subject of some controversy, with some 3rd-party tests finding that K&N's oiled cotton gauze filters are less efficient and let more dirt into the engine than original-equipment paper filters, and that they become increasingly restrictive as they are coated with particulates.
#DOES K AND N FILTERS WORK PRO#
K&N has maintained very active involvement in racing and motorsports throughout its history, including the NASCAR Pro Series East and West, the King of the West 410 Sprint Car Series, the NHRA, and Formula Drift. In 2019, K&N released a line of washable home A/C filters, and began offering motor oil and wiper blades in 2021. K&N also released a line of oil filters with a stamped hex to accept a standard wrench for filter removal. In 1992, K&N introduced bolt-on cold air intake kits. Air filters soon became the primary focus of the company. Johnson and McDonald sold motorcycles and motorcycle parts and supported a K&N factory race team. The name K&N came from the first letters in the founders' first names. A quick check reveals a K&N filter for the 2018 Subaru Crosstrek Premium costs $49.99 and that seems a little pricey considering the minor performance gains.K&N was founded by Ken Johnson and Norm McDonald in 1969. While it’s clear that non OEM filters did improve performance, there’s a question of whether they are worth it.
The K&N filter fared better as acceleration times improved by an average of 2.74 percent. Those are some pretty small gains, but are they noticeable in real-world driving? The differences between the clean and dirty OEM filters were negligible, but the cheap aftermarket filter did improve acceleration times by approximately 1.2 percent. This was the best performing filter, but it was only created 1.1 hp and 1.71 lb-ft more than the cheap aftermarket filter. Lastly, the K&N filter was installed and it allowed the engine to produce 164.42 hp and 142.53 lb-ft of torque. This is 3.22 hp and 3.39 lb-ft more than the clean OEM filter. According to the dyno, the filter enabled the engine to produce 163.32 hp and 140.82 lb-ft of torque.
The aftermarket CarQuest filter was actually kind of surprising as it did better than the clean OEM filter despite costing less. When the clean OEM filter was installed, the dyno showed the car produced 160.10 hp and 137.43 lb-ft of torque – a minor increase of 1.85 hp and 0.18 lb-ft.
Without further ado, the dirty OEM air filter enabled the car to produce 158.25 hp and 137.25 lb-ft of torque. They also used a VBOX to measure real-world acceleration changes. This allowed them to determine the horsepower and torque changes attributed to each filter. To conduct the test, the YouTube series installed the filters on a Subaru Crosstrek and then made multiple runs on a dynamometer. Performance air filters are billed as a cheap and easy way to add horsepower to your car, but do they really work? Engineering Explained wanted to find out so they pitted standard OEM filters against a low cost aftermarket filter and a K&N performance filter.