Club 80-90 Forums

Does anybody wish to share their experiences of using a K & N Air Filter on a 1989 2.1 litre petrol T25 please. Cheers.

Welcome to the club!

What type & size of K&N?

Not done it...
Expect more intake noise!
Unless it's hooked up to the high snorkel intake properly, I'd expect a reduction in performance

Put the K&N airfilter in the airbox

No noise then.

orrible things......loads of induction noise.....

K & N filters are very good, I have used them loads of times on Race cars and Bikes, never considered it on the van tho...

I wouldnt expect you would hear the induction noise over the engine

welcome to the forum.

K & N are not as good as stock filter. Slightly less resistance, but let alot more dirt into engine.
Techical filter test:
http://www.billswebspace.com/AirFilterTest.htm" onclick="window.open(this.href);return false;
laymen's filter test:
http://www.bobistheoilguy.com/airfilter/airtest1.htm" onclick="window.open(this.href);return false;

Yes, horses for courses, there's some bad ones, and some compromise ones (more air, more noise & more dirt.. fine for competition)
possibly the best thing is to change your stock filter element before it gets too blocked (& as I keep saying, especially on Turbo Diesels).

The point about a stock paper filter collapsing/blocking if it gets wet or muddy is good - but we don't even hear much (if any) of that even from the wading Syncronauts... so in the real world, s'not a big problem!

Thanks for the many responses. The links provided by Boyd certainly are helpful. Great stuff. I am still uncertain as to whether I should use a K & N. Maybe I'll sleep on it.

QU.

What have you got at the moment and why are you thinking of changing it.. ?

It's only an aftermarket paper filter in it right now. I was thinking that the K & N may improve fuel consumption and if a little power was gained at the same time, then that would be a bonus. Also, should they work satisfactorily, there is a cash benefit over a number of years as the K & N has a long lifespan compared to a paper filter.

K&N on its own will not alter the fuel consumption

Stay with the paper filter as VW intended

I love a good debate.

Everything on a mass produced production vehicle is a compromise, a compromise between cost,performance ( ie how well it does its job not as in power ) and longevity.

The OE paper element filters are cheap to produce, last fairly well and perform there main function of cleaning the dirt from the air before it gets into your lovely shiny cylinders, so over all not a bad compromise.

Research and development is a great thing.... we now have oils that perform and last much much better than those designed 25 + years ago , Tyres that are made from much better composites and air filters that have benefited from years of R+D.

The K+N was designed with a different set of compromises , cost was less important but longevity and performance ( both power and function of intended job ) where more important.

Im sure that if they cost the same as the paper element type and where around at the time VW would have used them.

Engines work by sucking in air, mixing it with fuel compressing and igniting the mix, basic rule the more air you get in the bigger the bang, so if you can get more air in whilst maintaining the cleanliness then all good.
One of the biggest advantages with these filters is that they can be cleaned as often as you like and will probably out last the van.
Would there be any performance increase ? In my ( humble ) opinion, yes probably very slight and maybe not noticeable, would there be a drop in fuel consumption? again probably yes a slight improvement. My thinking being that the more efficiently an engine works the less you have to push it to produce the same amount of BHP.

Fitting a free flowing exhaust would also help a lot, with my bikes changing the exhaust, air filter and carburettor needles would usually give at least 5 % increase in BHP and improve the MPG too.

P.S I dont use a K+n in the van, and probably wont, just wanted to add to the debate

I'm sure that if they cost the same as the paper element type and where around at the time VW would have used them.

Only if they filtered as well and the suggestion is that they don't - in fact some AFMs with hot-wire/hot-film (velocity/density type) sensing, don't like them for this reason... the film/wire sensor can become contaminated and then everything goes haywire
Came across this on a Subaru forum... dealers were gettinga bit annoyed, owners too, having to replace speed/density sensors

HarryMann wrote:

I'm sure that if they cost the same as the paper element type and where around at the time VW would have used them.

Only if they filtered as well and the suggestion is that they don't - in fact some AFMs with hot-wire/hot-film (velocity/density type) sensing, don't like them for this reason... the film/wire sensor can become contaminated and then everything goes haywire
Came across this on a Subaru forum... dealers were getting a bit annoyed, owners too, having to replace speed/density sensors

I've had a K&N style filter on my scooby conversion and its been as good as gold for 5 years! gets cleaned and oiled once or twice a year!