K%26N reusable air filters are definitely worth the extra cost upfront, because they are designed to last the life of your vehicle. If you've ever been to an auto parts store, you've probably seen air cleaner boxes that claim extra power and more torque than the factory filter. But being so cheap and easy to install, it's hard to believe that these filters actually produce observable gains. Well, Jason Fenske from Engineering Explained put these claims to the test, and it turns out that yes, high-performance air filters actually produce more power.
The standard air filter is almost never a restriction point. I've been using K%26N filters on my cars for 10 years or so. I'm not sure if they're really worth it, but I've never had a problem with MAF. I should disagree with this general statement.
In a normal passenger car? Sure, it's probably not worth it. However, once you find the need for a high-performance filter, the K%26N is an excellent choice. I bought a K%26N outlet years ago for my Subaru, and that same filter is still in use and looks new when clean. CRC Sensorklean to remove oil from MAF.
A couple of original equipment have it listed as a first step before replacing an iirc mass airflow sensor. I know Chrysler does it for sure. If you grease the filter too much, then yes, it will damage your MAF sensor and even clog your throttle. A simple solution for that would be to simply not overgrease the filter.
How do you know if you're getting too fat? In addition to videos you can find online and tutorials, the cleaning kit describes how to properly lubricate the filter. Find an offer (eBay, Amazon) to drop in and try not to pay full price. k %26 N itself is decent. But it's almost impossible to clean them well, oil CAN affect the MAF and dirt sticks to the oil, meaning filters can clog more quickly.
If it's for a daily driver, I'd say no. If you're trying to modify a project car, there's no reason not to, but I highly recommend Specter over K %26 N. You'll never get a big power boost with a cold air intake, but it doesn't sound so bad. It depends on what your goal is.
If it's to increase HP, no, it's not worth the money. If you're looking to eliminate the need to buy an OEM-style replacement air filter every time you make your adjustments, it will take you a few years to get the most out of it. But if you're looking to increase MPG, an air filter that provides increased airflow to your intake manifold while keeping the air relatively clean and free of debris will give you an increase in miles per gallon. If the car is standard, the air filter you have is designed to provide enough air for maximum power.
I put in a cold air intake and eventually my car would shut down at the most inconvenient times (i.e. roundabouts) and it ended up being the mass air flow sensor that failed. I change the air filter approximately every 20,000 miles, and at $10 each time I would have to keep the car for 100,000 miles to make the k%26n worth it. It depends on the car, if you already have an air box that is supplied with cold air from outside the engine compartment, it can make things worse if you take it all out and put in a higher flow filter, but drawing air from under the hood.
It suggests that the increase in power could be the result of less filtering, especially in the case of the cheaper CarQuest filter, although because it had no way of testing the filtering process, that aspect was not observed. He finds that on the test bench, aftermarket filters actually produce more than the OEM unit, with the largest gains produced by the K%26N filter (around four horsepower and five pounds). It means you have a filter that you can clean and re-grease, which is good, but some find that they contaminate airflow sensors if a little excess oil is applied, so that may be a consideration. If modified, i.e.
fluid heads, cams, exhaust, then they are the best filters you can get, in my opinion. I didn't install it because of the marginal increase in power or to save money on annual replacement of air filters. What Fenske doesn't prove is how well each aftermarket filter actually filters the air entering the engine compared to the original unit. I remember reading an article in Performance Ford where they tested the same car with stock, k+n cone, cheapo cone and then drilled 2 inch holes in the air box under the filter panel.