The big problem for me is that they don’t filter as effectively.
That is one hell of a statement, where did you get that idea from?
1 Like
Google is your friend, Malc.
It would be better to just quote your source. Much easier and more effective for discussion.
Are you saying that the increased airflow through an aftermarket filter such as a K&N is at the detriment of the actual filtering of the air that is passing through it?
1 Like
Correct.
Here’s a nice graphic from an independent test. AC Delco will be a standard paper filter.
About 4% of the dust is getting into the engine.
Another AC Delco v K and N comparison…
“Compared to the AC, the K&N “plugged up” nearly 3 times faster, passed 18 times more dirt and captured 37% less dirt”.
Eat one less pie this week and you’ll gain more power than fitting a K&N filter.
Any power giains are so minimal that you won’t notice. Consider they are about £40 as a opposed to £5 for a paper filter and it will be 8+ years before you get your money back, and that’s if you change the air filter annually.
Maybe if nothing, they may give you a bit of induction roar so might sound faster.
Where are these £5 air filters available from?
OEM is £27 in the mx5 parts shop.
also even if I take these numbers at face value… you are talking a delta of 97% vs 100% assuming the tests were conducted by a non-biased body.
I will take better noise any time rather than argue over “3%”
IMH biased opinion of course 
3 Likes
MX-5OC: Noise Matters
1 Like
Most definitely. I paid approximately just shy over 2k mostly to have a nicer noise with a little bit of performance increase (+26 hp, + 10 lbf). I would do it in a heartbeat just for the noise…
Personally, I don’t want any grit in my oil. The oil filter might get it before the next cold start, or it might not.
I thought we were on air filters not oil filters!!
1 Like
Think you will find he is talking about the “oil” in the element of the the K & N filter.
If sand gets past the air filter and into the combustion chambers does it turn into glass?
1 Like
Yes, I am sure I have seen something on the internet that proves that this has proven to be the cause of ‘glazed’ bores!!!
I had a K&N on my RS2000 years ago…
But on the ND i have Blitz SUS Power LM only because it came with stickers.
Another downer on the subject is that as you are going to “modify” your car you have to inform your insurance company who may like to increase your premiums.
You can also forget about claiming for any mods made should you have an accident if they didn’t know about them. Insurance companies are “oily” at the best of times, never helpful when you want to claim!
1 Like
So I guess all those people out there that use Bosch, Mann,K and N and all the other brands have modified their car.
Don’t think so in my opinion, it’s just another air filter that sits in the same air box at the end of the day.
One could say the same about oil filters, brake discs, pads etc etc
4 Likes
Nope… you buy modified car insurance declare all mods and get an agreed value on the car…