Is there a downside to K&N or Green Filters?
Discussion
Hi everyone,
I often see performance air filters advertised, such as K&N and Green. Is there a downside to them in the car?
On the bike, I've heard two mechanics advise against using them. The advice was that whilst they let in more air, but didn't filter as well as an OE filter. Any thoughts?
I often see performance air filters advertised, such as K&N and Green. Is there a downside to them in the car?
On the bike, I've heard two mechanics advise against using them. The advice was that whilst they let in more air, but didn't filter as well as an OE filter. Any thoughts?
As far as I know, the only reason the manufacturers don't fit these life long air filters, is that it's less profitable in the long term (re servicing etc).
They don't stop as much dust getting through (you can actually see daylight light through a K&N), but what does get through is soooo small that it shouldn't cause any issues.
They don't stop as much dust getting through (you can actually see daylight light through a K&N), but what does get through is soooo small that it shouldn't cause any issues.
Can't comment on greens but having rebuilt heads on cars that have used k&n they pit the exhaust valves quite badly thanks to letting all manor of crap through namely grit that then super heats and pits the valve seat - do they increase performance? Yes - but you may as well run with no filter - in the long term you'll see decreases in performance over a period of time
Heatsoak.
On an open cone filter without any shielding (which appears to be the most commonly sold type), the engine just ends up sucking in warm less dense air from the engine bay and you may loose power. On K&N filters (and certain other brands) that are oiled, this oil can coat the MAF sensor (if your car has one) and cause it to mis-read. This can be cleaned sometimes, or worst case, you'll need a new MAF.
Filtering ability should be fine, and they tend to be less restricitve than a standard setup, but unless you get a good cold air feed, all it will really do if make more noise (though induction noise is lovely, so may be worth it to you).
On an open cone filter without any shielding (which appears to be the most commonly sold type), the engine just ends up sucking in warm less dense air from the engine bay and you may loose power. On K&N filters (and certain other brands) that are oiled, this oil can coat the MAF sensor (if your car has one) and cause it to mis-read. This can be cleaned sometimes, or worst case, you'll need a new MAF.
Filtering ability should be fine, and they tend to be less restricitve than a standard setup, but unless you get a good cold air feed, all it will really do if make more noise (though induction noise is lovely, so may be worth it to you).
I have used K&N/pipercross filters on most of my cars and bikes since driving.
For the RGV250 and RS250 the norm is to replace the standard filter with a pipercross item. For my current car (Focus ST Mountune) the filter supplied by mountune is a K&N item, K&N induction kits are also a common fixture on fiesta ST's.
My Speed Triple and Focus have a K&N and my GSXR 750 and RS250 have pipercross filters.
Some cars can suffer from heat soak if an induction kit is used and the filter is situated in the wrong place or does not have enough air getting to it. Generally them need cleaning more often than standard filters but as a filter clogs up it will actually filter better
For the RGV250 and RS250 the norm is to replace the standard filter with a pipercross item. For my current car (Focus ST Mountune) the filter supplied by mountune is a K&N item, K&N induction kits are also a common fixture on fiesta ST's.
My Speed Triple and Focus have a K&N and my GSXR 750 and RS250 have pipercross filters.
Some cars can suffer from heat soak if an induction kit is used and the filter is situated in the wrong place or does not have enough air getting to it. Generally them need cleaning more often than standard filters but as a filter clogs up it will actually filter better
SVS said:
OK, that's reinforced what two mechanics have told me. It's a No from me for K&N then.
I guess it's personal choice - I'm sure many will diagree with me but I personally can't recommend them based on what I have seen - some other people in the trade have said the foam type are better but I haven't looked at the valves of an engine that has run one so can't comment - As mentioned by others heat soak is also an issue SVS said:
Hi everyone,
I often see performance air filters advertised, such as K&N and Green. Is there a downside to them in the car?
On the bike, I've heard two mechanics advise against using them. The advice was that whilst they let in more air, but didn't filter as well as an OE filter. Any thoughts?
A huge issue is the stickers you get given with the pads.I often see performance air filters advertised, such as K&N and Green. Is there a downside to them in the car?
On the bike, I've heard two mechanics advise against using them. The advice was that whilst they let in more air, but didn't filter as well as an OE filter. Any thoughts?
Should you happen to put them onto your car, you will medically catch "chavitis". it's an age old issue since the addition of striped carrots back in the horse years
I've seen a bench-test article a few years back where they compared various filters. The OEM paper air-filter performed better than the modified air-filters. The foam filter was in the middle. If a paper filter is dirty then it won't flow that well. But they only cost a few £££ to change and a very small amount of time. So I'm never going to buy a modified air-filter because the OEM one is better.
Just keep them clean.
Just keep them clean.
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