K&N air filters – worth it or a waste?

Seen loads of ads in motorway service station toilets recently for K&N air filters. 😯

Are K&N air filters worth the money over their paper counterparts?

Do they work? (ie increase in engine performance (although I'm not expecting miracles))

I am sure they provide better air flow as I've seen a live demo years back but would welcome some STW advice / abuse / sarcasm * delete as necessary

Big thread on this amonth or so ago. Canyou search previous threads on here? Might be quicker and less painless than sifting through the usual incorrect and sarcy remarks you'll no doubt get. 🙂

Put one in my triumph tiger and pulled the baffle tube. What a difference. Plus they can be cleaned, oiled and re used.

Probably a couple of horse power

I would say yes. Have a K&N cone filter on the MG and box filter on 2.0 Ford Zetec. Noticeable difference on the MG, performance and fuel wise (especially when combined with extractor manifold and big bore exhaust) and +1-2 mpg on the Ford with cleaner revving top end.

Worth it if that sort of thing is of interest but not as a cost saving exercise on filters.

I don't think it's a big deal. It's certainly not a difference you can tell when you're driving – perhaps a 1-2% increase in power? One thing I have noticed when looking at cheap methods of getting more air into an engine is that the entire range of a model often has the same air filter and air box specified, say from the 1.4 to the 3.0 Golf. If the filter you have can flow enough for a 3 litre engine and you haven't got one, you haven't got great chances of making a difference.

There can also be issues with some types of sensors in the inlet being screwed up by the oil from the K&N I believe.

Personally, my attitude to tuning is mainly one of chip it if it's got a turbo, or buy a faster car. They're the cheapest routes to more speed.

That said, I would do an engine swap to my Golf if I had the cash 😆

There's also much more of a chance of a K&N / exhausts making a difference on a really old car (ie, 1970s or earlier) when one of the main methods of quietening an engine was to strangle it a bit with narrow intakes and exhausts.

In the eighties when I was seriously into this kinda stuff it made my bike sound much much faster. Defo worth it.

Used to put them om my MGs but IIRC you only got the extra if it was combined with an extractor manifold and I think you had to change the needles. Can't see you 'feeling' the difference with just a filter swap in a modern car.

In the eighties when I was seriously into this kinda stuff it made my bike sound much much faster. Defo worth it.

Likewise, it generates a nice throaty roar, never noticed any difference in power though.

Depends on the car, if its already got an air box which is fed by cold air from outside the engine bay it may make things worse if you take it all out and fit a higher flowing filter but drawing air from under the bonnet.

Also. Ask yourself how much time you actualy spend at full throttle? If it's not 100% of the time that your not braking then its probably not worth it as you could just get more power by using the noisy pedal more.

http://www.carbibles.com/fuel_engine_bible_pg5.html

It'll make you mentally feel like its making a difference. Thats it. As said, older car -yes.

If you are keeping a car until you run it into the ground then yes- you don't have to change it regularly.

Depends on the car, if its already got an air box which is fed by cold air from outside the engine bay it may make things worse if you take it all out and fit a higher flowing filter but drawing air from under the bonnet.

Not all K&Ns are full replacement boxes, you can get replacement panel filters to keep noise down and still get an improvement. But the point above is a good one, if your engine is not the one at the top of the range but still uses the same intake setup you'll probably see little gain from it. It's a case-by-case scenario, and asking on a bike forum is going to leave you with a bunch of people who either do or do not believe in them based on their use on their car, rather than your car. My advice would be to decide why you want it. It's not just for full power (restrictions affect pumping losses at all revs, just less so lower down) but it likely won't make much difference unless your intake is very badly designed or you've modified the rest of the engine to suit (improved VE etc). It does mean you have one filter you can clean and re-oil which is nice, but some find they contaminate air flow sensors if you slightly over-oil so that may be a consideration.

I agree with coffeeking and thisisnotaspoon.

I have had them on previous cars when I had lots of disposable income to spend on such things and when I wanted to have a bit more noise under the bonnet.

I would not buy one now though for my current car.

they come with a cool sticker and they sound nice.
I used to have one on my Fiesta Supersport.

The rise in bhp is often ruined by a drop in torque.

only if you do other mods..

did some back to back trials on a rolling road using a modern cars (clio, fiesta and fitting the K&N 57 kits, all cars fitted lost a bit of power but did sound 'sportier'.

Think about it, manufactures spend a lot of bucks in design to get good source of cold air, quietness and filtration, if it was as simple as sticking a code filter on a bit of drain pipe they would come like that.

having said that the cotton filters works well as cleaning the air and can be washed etc.

I think ITG filters are better though, though for older cars not so shiny and chrome. They are also helpful, sending me some bits to help when I made a GRP airbox/back plate for my throttle bodies.

i remember reading an article in performance ford where they tested the same car with stock, k+n cone, cheapo cone and then drilled some 2 inch holes in the air box below the filter panel. each was tested on the rolling road and the dilled box had the biggest increase for the bargain price of 0 pence

Makes a very slight difference but probably the only noticeable difference will be the awesome sound it now makes 😉

The typhoon kits are popular with people on a car forum I use but there was a problem (I can only speak about Corolla's) with holes being blown through the pipe that attaches it.

For the money I would say its not worth it as a standalone mod, if used in conjunction with other engine mods then maybe worth the time/money.

It will also increase your insurance 😉

If the car is standard then the air filter that it has is designed to provide enough air for maximum power. So you will be wasting your money.
If its modified ie flowed heads, cams, exhaust then they are the best filters you can get in my opinion. 20yrs modifying cars/rallying etc.

As inbred456 said, they are an appendage to other bits of tuning, and I would not bother unless you are getting other tuning work done to the induction and exhaust system as well.