911addict

My car has just come back from its annual service. I wanted to try a K&N filter. The garage said it caused strange variations with the idle/ mixture, so they put in a new factory filter instead. But see my other post on fuel mixture in case this was the reason https://rennlist.com/forums/964-turbo-forum/324842-fuel-problem-again.html

On the drive home, I noticed I can hear the 'sucking' of the filter at high revs, whereas before I couldn't (sounds healthy). I guess that shows how our filters get blocked up over time.

Anyone else experienced similar issues with changing the airfilter?

Megatron-UK

Been running mine with a K&N since just after I got it. No problems with idle whatsoever.

Can't really understand what the garage seem to be talking about, tbh - it's just an element that goes in place of the original.

Unless you mean a K&N cone job that you replace the airbox with?

911addict

I have in fact read that if the K&N is over-oiled it can cause all sorts of problems, mabe that's it.

btw, what's yours like, any noticeble improvements?

Y65MPH

Some of the oiled filters can cause some issues. I am using a Green filter and it is great.

rob964.c4

the over-oiled could be a problem,
I've tried a K&N and now have a BMC filter works perfect or ok, no extra HP no extra sound.



robert

Megatron-UK

Seems to work ok. No problems with idle or throttle response. Only a few quid more expensive than an OE filter and I'll just clean it and re-oil for the next service. I've never had a problem with them on any of my cars tbh.

The 'Green' filters that Y65MPH mentions are also pretty good - they're not oiled like K&N, so don't have problems on those cars that use a hot wire based air flow meter; I had one on my 2 litre turbo mk1 MR2 - not a problem, and mega cheap too.

There was a little increase in induction noise when fitting the K&N, but nothing as intrusive as a cone filter or removing the airbox. The cat bypass is much, much louder (and the pops and bangs on downshifting and over-run are clearly from that - rather than anything the air filter is doing).

nathanUK '81 930 G50

I found there was more induction noise on my 3.2 carrera when I changed the paper for a K&N element.

dholling13

The BMC filter kit on my turbo was noticibly louder under full boost load. Plus, I can actually get back there and work on the car! It too uses the K&N filter service kit comprised of cleaner and spray on oil...

cobalt

I have used the K&N on my Porsche's since K&N came out with them. No major gains just easier than replacing as often as the paper. The problem with the K&N is improper oiling by the owner. Although I do not use them on my cars with hot wire.

I also drilled my air box which makes for an improved sound. I punched 7-1" holes on the bottom side. Hard to tell if it helped or hindered performance but it sounds better.