K&N air filters

bmw535d

are they worth the on average 50 euro extra over a normal air filter or are they a load of ****e with good marketing?

bladespin

Not sure how much of a performance boost you'll get but they make a nice noise and last years. They pay for themselves by being washable.

Viper_JB

Definitly worth it, it's the only air filter you'll need to buy for your car, good high air flow with them...and not all that expensive, you should make up the extra money with better fuel consumption and not having to buy an air filter on a yearly basis.

bladespin

Viper_JB wrote: »

Definitly worth it, it's the only air filter you'll need to buy for your car, good high air flow with them...and not all that expensive, you should make up the extra money with better fuel consumption and not having to buy an air filter on a yearly basis.

Yearly, I go through them every 8k miles, that's 2-3 changes a year.

I got a panel one for my ZT to enjoy the V6 soundtrack a bit more. Can't say I noticed any difference in mpg and the filter in there was fairly manky. Noticeable difference in induction noise though, nothing intrusive though. Are you thinking of a panel filter or a cone ??

biko

Performance wise I don't think so, but they are long lasting.
Depends on the car etc.

PaulKK

I read before that these have a habit of breaking MAFs, due to the oil on the filers, and allowing more crap through due to their higher flow rate.


If its for a turbo diesel, I wouldn't bother, you aint going to improve your airflow any more than what you've got.

bladespin

PaulKK wrote: »

I read before that these have a habit of breaking MAFs, due to the oil on the filers, and allowing more crap through due to their higher flow rate.

Never heard that but cleaning a MAF is a very simple thing to do, if oil's going into the system then the filter's after being soaked in the stuff, I've used them on nearly every bike I've owned and never had a problem with oil mist, follow the manufacturers guidelines.

bmw535d

2.8 shogun with 185,105 miles, i doubt a maf will be the biggest of my problems as it doesn't even have one which is why there is so much black smoke no power and poor fuel economy as it isn't getting enough air for the amount of diesel its pumping in so she running way to rich. so i thought id start with the cheapest and most obvious suspect(air filter) a normal one is a fiver on flebay and a k&n is 55 or so. hence this thread being made.

after that next step would be to sort the boost actuator spring. but thats a job for another day...

Stevie Dakota

I removed one (panel) from a previous BMW after hearing that they did not filter as well as paper, and I wanted my engine to last. Certainly more noisy if you like that sort of thing, but don't expect any noticeable performance increase.

People also treat them as lifelong, so don't clean them or oil them like you are supposed to. Cone ones also need a fresh air source, drawing air in from around the engine is no good.

Overall I think they are a gimmick.

PaulKK

PaulKK wrote: »

you aint going to improve your airflow any more than what you've got.

how so ?

mullingar

K&N definitely have the "brand" power behind them and are the biggest seller , IMO I think they got to that level by people buying them because they didn't know any better.

I would suggest NOT to go with K&N, but a proper foam filter. The K&N relies on oil to trap the fine debris in the air. If you look at a K&N filter its nothing but 1000's of holes.

IMO A foam filter on the other hand does a much better job and is 100% dry and oil-free. The foam is similar to the foam filter inside a dyson vacuum cleaner ;)

I have this cone-filter system in my GS300:
http://www.aempower.com/

And I LOVE the WOT induction roar from the L6 engine :D:D

ianobrien

When delivering a (rather large) pile of performance parts to my engine builder for a job for me, there was a nice K&N filter there. He told me, in rather vocal terms (that sounded like sit, but with a soft "s") what he thought of them.

I was "encouraged" to get an itg filter.

I must preface that by saying that it was a performance engine running on Weber Carbs and not Fuel Injection.

mullingar

ianobrien wrote: »

I was "encouraged" to get an itg filter.

Its also a foam filter. (but with oil AFAIK)

bmw535d

what about pipercross?

mondeo

I use to go for the 'ramair' filters in the late 90's in my little hatches I use to run around in. Expensive though! Won't give you a gain if any on a small engine other then noise...

ianobrien

mullingar wrote: »

Its also a foam filter. (but with oil AFAIK)

All I know is what my engine builder recommended.

Also, quite a few of the top race/rally engine builders use itg filters, and money is not a problem on these builds (with price tags of 20K plus for a 300hp plus for a Duratec and no forced induction)

PaulKK

RoverJames wrote: »

how so ?

Well i dont claim to be an expert but from what i have read most turbo diesels already have a very efficient airflow delivery method that would be difficult enough to improve on. I looked into it before and decided against it because of the use of oil in these filters and the tests that show the amount of crap they let through. I dont know about most people but i'd rather be sticking in new oem filters each time than trying to clean out a reusuable filter. I'm sure these filters have their place, and in my opinion that is most likely for larger capacity normally aspirated petrols.

mickdw

Oiled filters are not to be used where there is a modern MAF sensor after it. Even following the oiling recommendations, it will over a few thousand miles foul the sensor wire and cause running problems. Sure the MAF can be cleaned and this will fix but care needs to be taken in cleaning the MAF too as it is easy to damage it or to simply clean it with an incorrect product which may leave a residue and again cause it to read incorrrectly. Certainly main dealers will just swap out for a new MAF and not do any cleaning.

Neilw

mickdw wrote: »

Oiled filters are not to be used where there is a modern MAF sensor after it. Even following the oiling recommendations, it will over a few thousand miles foul the sensor wire and cause running problems. Sure the MAF can be cleaned and this will fix but care needs to be taken in cleaning the MAF too as it is easy to damage it or to simply clean it with an incorrect product which may leave a residue and again cause it to read incorrrectly. Certainly main dealers will just swap out for a new MAF and not do any cleaning.

Have an oiled ITG filter on my car for over 50k miles now and no issues with the maf, it's 100%.
Every previous car I've had had a k&n oiled filter in it and again no issues. A friend of mine bought my last car and it's at over 80k miles and it still has the original k&n filter in it, no maf issues either.

It is possible to over oil a k&n, that might cause problems but if you are careful there should be ok.

As for the ITG, the oil is like tar and there is zero chance of it getting pulled onto the maf.

PaulKK

PaulKK wrote: »

Well i dont claim to be an expert but from what i have read most turbo diesels already have a very efficient airflow delivery method that would be difficult enough to improve on. I looked into it before and decided against it because of the use of oil in these filters and the tests that show the amount of crap they let through. I dont know about most people but i'd rather be sticking in new oem filters each time than trying to clean out a reusuable filter. I'm sure these filters have their place, and in my opinion that is most likely for larger capacity normally aspirated petrols.

I reckon that's not true in the majority of cases, many factory air boxes and inlet air pipes are quite restrictive and can be approved upon. Tiny improvements yield decent gains as diesels suck air like mad.

mathepac

PaulKK wrote: »

I read before that these have a habit of breaking MAFs, due to the oil on the filers, and allowing more crap through due to their higher flow rate...

We have a K&N oiled filter on the remapped turbo-diesel for the last 90k miles and neither the MAF nor anything else has failed. Just passed the NCT today with flying colours (big turbo, big intercooler, EGR bypassed, no CAT, remapped - now planning to change the injectors and go to a stage 2 remap)

IME MAF "failure" has less to do with after-market oiled air-filters (properly maintained) and more to do with poor electrical connections to the sensor itself. If the MAF matrix does get clogged with "stuff", iso-propyl alcohol assiduously applied with q-tips donated by the kids or missus and can usually fix it - ah yes, modified motoring, the complete family hobby

Where K&Ns or similar do cause problems, it is normally down to poor maintenance, improper seating in the air box (as they are less than half the depth of a paper element they can be awkward to seat properly) or in one case I saw due to an idiot with an air-line trying to blow debris out.

Oiling a K&N or similar, after proper washing and drying, should only be done on the "dirty" or pre-MAF side. I have seen them oiled on the clean side and this will definitely pollute the MAF.

Foam and paper filters on re-mapped turbo-charged engines make me nervous about bits breaking off. I like the feelings of security a nice tough sandwich of steel mesh and fabric like the K&Ns offer; it might be irrational, but hey, that's me!