So I'm about to change my air filter on my 2019 Fiat 124 Spider, and was looking at a K&N performance filter. But i've seen lots of different opinions on what to use. Some say only use OEM filters, since mopar is saying that their filter is made specifically for this car, others are saying some aftermarket performance filters are better. What I've seen with some performance filters is that because more air can be let in through the filter, more crap can be sucked in and damage the engine. But also having an performance filter will not only increase oxygen and have better combustion, it'll increase a little bit of power. I was looking at K&N filters, but there's some mixed reviews apparently. What kind of filter is best for turbo engines, if that matters. I've seen BMC, K&N and another brand I don't remember. Is performance filters good for just street driving? Or mostly for racing. I don't race my car, but if it helps smooth out power and whatnot, I'll get it, but if OEM paper filters mean better filteration, then I'll get that. I've seen different answers so I want to know what yalls opinions are.
Best air filter?
- Thread starter Toaster
- Start date
MANN
The pressure drop across a typical OEM air filter at wide open throttle is less than 1% of atmospheric pressure. This means that a high-flow filter with half the restriction will result in a power increase of less than 0.5%. Some engines might see more of a benefit, but they're the exception.
The downside is that a K&N might allow 10 times as much dust into the engine compared to an OEM filter. If you only drive on paved roads, that might not be a big deal, but I don't think it's a very good trade off outside of competitive racing.
The downside is that a K&N might allow 10 times as much dust into the engine compared to an OEM filter. If you only drive on paved roads, that might not be a big deal, but I don't think it's a very good trade off outside of competitive racing.
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Man I fell for K&N in 1998 because my car forum said 2-5 HP gain. Boy was I naive. The tens of thousands of miles of mpgs suffering, buying their clean and reoil kits. Then some dude shows up online with bench test equipment costing millions and provides empirical evidence that it’s snake oil.
The negligible improvement in power / mpg and the worse filtration of these 'fad filters' has been mentioned.
Don't forget the likelihood of the oil fouling the MAF sensor.....just to complete your education.
As far as your dusty environment goes, I believe more frequent changes is all you need.
I make the effort to clean the air filter's box when you have it open.
Some cars will show you a cleaner AF housing than others.
My wife's Mazda CX-5 was real clean. My P2 Volvo accumulates a load of dirt.
Don't forget the likelihood of the oil fouling the MAF sensor.....just to complete your education.
As far as your dusty environment goes, I believe more frequent changes is all you need.
I make the effort to clean the air filter's box when you have it open.
Some cars will show you a cleaner AF housing than others.
My wife's Mazda CX-5 was real clean. My P2 Volvo accumulates a load of dirt.
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oe or quality aftermarket would be preferred by me. microgard is a good aftermarket choice.
I’ve got a K&N on a bMW with 200+K with 3-4 cleanings, no problem. I also run regular OEM filters 70-100k.
OEM, Purolator, Premium Guards. The k&n's have shown to allow more contaminates through on some yt vids. 
However, that doesn't necessarily mean damage wear that reduces engine life in any measurable way. So long as it's maintained properly. Some have run a K&N for hundreds of thousands of miles.
However, that doesn't necessarily mean damage wear that reduces engine life in any measurable way. So long as it's maintained properly. Some have run a K&N for hundreds of thousands of miles.MAF gives more precise air flow readings, German cars as an example have MAF mostly.
It's not just some Youtubers showing that K&Ns have poor efficiency, it's also their own published ISO test results.OEM, Purolator, Premium Guards. The k&n's have shown to allow more contaminates through on some yt vids.
There's also this independent ISO test, where the K&N passed 45 times as much dust as the most efficient paper filter tested, and 3 times as much as the worst paper filter.
The reason some engines can go hundreds of thousands of miles with poor air filter efficiency is that those vehicles are probably not often driven in really dusty environments. In non-dusty environments, air filtration efficiency hardly matters. In very dusty conditions, abrasive wear becomes the dominant source of wear, and filtration efficiency matters a lot.
Here's a comparison of piston ring and liner wear between two paper filters and a low-efficiency oil bath filter. When dust concentration is low, there's little increase in wear over baseline. In zero-visibility dust conditions, wear is 75 times higher than baseline with the oil bath filter, but less than doubled with the paper filters. Of course, a K&N filter has better efficiency than an oil bath filter, but it would still cause much higher wear in dusty environments than a good paper filter.
Thx, twX. The link points to more good AC Delco results.
BrendanC
$100 site donor 2024
paper air filter is all i will use on anything i work on. usually carquest red units if they have them as they are cheap. we change every 12k miles due to heavy industrial use. they come out disgusting but the intake tubes are always squeaky clean.
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OEM only (or at least get a paper non oiled) a few months back I was curious just like you, so I decided to buy a TRD oiled filter , which is pretty much a KN filter . After 2 weeks, I took a look and noticed that the filter pleats looked wierd and I did not feel comfortable with running the TRD anymore. It may have been fine and maybe im just a little ocd, but I’ve never had this happen with any oem or paper filter. So I’d stick oem . Here are some pics. 3 pics of before install and 3 pics of 2 weeks after install.
Because fit is so critical on the engine air filter, I always stick with OEM. I've had a few aftermarket filters over the years that had fitment issues, so now I don't ever veer from OEM. For oil and cabin filters, yes. But not for engine air filters.
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