K&N Filter info

[(RIP) Kaister]

taken from a saab forum - which came from another forum

http://www.900aero.com/phpBB2/viewtopic.php?t=566&highlight=stall

i agree that K&N's are rubbish , having used them as a spotty yoof on an RD350 and ended up binning them as worthless junk .

DYOR though - nothing is gospel unless you know better.

 

[sproggy]

A GS is not a Saab 900, neither is it a Porsche 928. The fact that a K&N doesn't add power to a 928 suggests simply that the 928 has a good filter arrangement from the factory - it doesn't mean that a K&N won't add power in any application.

BMW bikes don't use Mass Air Flow (MAF) sensors so that criticism doesn't apply either.

So the only criticism remaining is that 'too much' dirt gets through. Well, 'too much' by who's definition? Common sense says that if you install a freer-flowing filter it will let more dirt through than a more restrictive one but most people either don't care or do care, but consider that the trade-off is acceptable.

 

[Le singe]

Perhaps all the race engine builders who use them are wrong

 

[Mzokk]

I use a K&N filter in My GSXR600. Not for any performance boost but for economic reasons. The Suzuki paper element is supposed to last about 12,000 miles but is clogged after about 6 or 7kand is about £22.00. A k&n is about £45 and will last for yonks if cleaned and re-oiled. Materials for which cost £12 for 10 cleaning cycles. Paper elements on the BM are cheap and the one I took out at 12K looked as if it would have done a fair few more miles so no point in a K&N. Tuning bikes is OK if you want to tinker. But for the road your just better off buying a faster one if you need more speed. Otherwise you could spend a fortune making a slow bike slightly less slow.

 

[Le singe]

I agree,tuning for a higher bhp figure that you'll probably only use in the pub isn't always the way to go.
But tuning for more midrange can be beneficial.
I ported and twin-plugged the head on my brother's aircooled twin,optimised,(as far as possible),the squish and re-jetted the carbs.
He now has stronger acceleration and regularly gets over 10 more mpg. For the road this sort of tuning is ideal.

 

[(RIP) Kaister]

the basic point is that the filtration efficiency is reduced - ref the fleet owner whose oil analaysis showed increased silica - ie airbourne particulates and dust.

Race engine builders need short term filtration - we used them at mclaren as a flat plate element - but replaced it every day - you want to do that to maintain effeciency ? I think not.

I don't think the trade off is acceptable and am not conned into thinking i'd get more power by fitting one..
I've seen flow graphs showing zero pressure drop across OE filters at WOT - so how can there be any benefit by fitting a K&N ?

Anyway - its only info - do as you like

 

[Tarka]

Common sense says that if you install a freer-flowing filter it will let more dirt through

Not strictly true mate. Filters like K & N have a larger surface area than the original,by having more pleats in the same sized area. They filter to the same,or possibly finer,standard,yet flow more air

 

[(RIP) Kaister]

Filters like K & N have a larger surface area than the original,by having more pleats in the same sized area. They filter to the same,or possibly finer,standard,yet flow more air

not even slightly true, i'm afraid - oh broken-footed one

Take an OE paper element filter apart and lay it on the ground - it'll cover about 3 sq m. ( if you're bored )

A K&N has a few pleats to try and increase surface area , but its nowhere compared to the folded paper pleating.
The whole thread is saying they filter LESS - ie larger particles get through a K&N .

They 'supposedly' flow more air - but only compared to a dirty original paper element.

 

[Le singe]

I think they're popular in England because it's rarely dry enough to promote truly dusty situations!
It's true that they do let more fine particles into the engine,but,with sportsbikes and the like,3000 miles and one year later it's back on the showroom floor and you don't care.
With the BMW I'd be suprised if the filter,(standard paper),gave a measurable loss of power.
I personally cannot feel a difference of 2 bhp at peak power,as 99% of riding time is spent below the redline,the air filter element is being asked to operate at far less than it's maximum capability,therefore why change?

 

[garyfzs]

surely,more air flow = more shit in the engine =less life in the engine, I'll go for standard paper filter

 

[Mzokk]

Have to disagree Le singe. I regularly ride with a group of sports bike riders who clock up 12-15k plus on sports bikes PA including right through the winter. Recon I'm a bit of a poof for riding my BM/MZ in the winter. That little GSXR in my avatar has clocked up 26,000 miles in two years (all summer use INC touring but no commuting) Interestingly I bought the BM privately in June Two years and two months old 5003 Miles However, never let a sweeping generalisation get in the way of a good discussion.

Interesting to hear Motomartins comments on the filtering efficiency of the K&N. I would imagine the filter is most efficient when it’s clogged..........when the pressure drop across the filter cuts performance. I wonder why off road bikes and desert racers use foam filters if the engine bore wear is liable to be unacceptable?

Is sticking with K&N because it’s a cheaper system liable to cost in the long run? I'm pretty fastidious about oil changes and use Synth Oil how does this fit into the wear senario.

 

[Taipan]

I think K&N relied heavily on their laurels. A lot of their filters only flowed as good as standard. Some flowed even less (SV650 k100). The original SV650 one was so poor it had to be redesigned. Ask K&N about that!

What does happen is people over oil them and reduce flow. I've seen bikes on a dyno running rich despite a freshly cleaned and oiled filter. Once cleaned and lightly, read properly, oiled the mixture changes considerably. Dont forget its the oil that really is the filter medium, not the actual element. Less is more where flow is concerned.

Some race applications use K&Ns and Pipercross filters absolutely dry. But then they aren't worried about engine rebuilds whereas we probably are.

I've used K&Ns and Pipercross (my preference) in road applications, but not for extra flow, just economy. Its a hell of lot cheaper to clean and reoil these filters than buy some OEM ones.

 

[Le singe]

Mzokk, after reading about your mate's mileages,I now realise that my original comment about the low mileages achieved by the average sportsbike rider was incorrect.
Clearly,the bikes that are just a year or more old on the showroom floor,usually showing only a few thousand miles,are just being stored there by the owners and not for re-sale.