Putting in my O/Hed MAF and my car has a K&N filter, so is it just mine or are they a poor fit, it looks to be about 1/2 inch to long to fit in. Do they swell with time? Or did different year air cleaners come in different lengths?
Dan
87 S4

 

Get rid of the K&N and replace it with OE. The K&N's oil can contaminate your air metering system and the original is an excellent filter.

Keep in mind that the 928 air filter is also used in the Bugatti Veyron (x2)...

 

I think that you're going to get a lot of recommendations to go back to stock. Given how the MAF works, with the burnoff cycle after the engine has been turned off, the K&N filter will work against that by continuing to provide oil/vapors that will contaminate the filament.

As to answering your question, I don't think that there are different lengths of air filters. I don't know if they swell with time, but I removed the K&N filter that was in my car and didn't observe an issue with fitment.

Cheers

 

NOTE the above information about the oil laden air contaminating the MAF wire not withstanding.

Please consider, the KnN advertising team did a great job, that to whomever put that part into your intake system.

If you look carefully you will find a fine layer of micro particles that have come past the part and is laying/sticking on the lower air cleaner housing.
get a white T shirt and wrap it around your finger then wipe the housing, you will see this for yourself.

NOTE This same air has also gone into your cylinders and has been wearing out the cylinders, rings and pistons.
The factory filter flows great and catches 6 times as much grit as the dirty KnN does.
NOTE The hump points to the sky on the factory filter.

 

Get rid of your K&N filter.....period.

 

I found that the OE filter has a better seal on the 928 than a K&N. Over-oiling is the issue with K&N filters.

We have ran them in our Mercedes, Porsche 944s, and our GM trucks in the family with great success. I am very conservative when re-oiling after a thorough cleaning. Been doing it for 2 decades now with no issues

However, based on my experience with a K&N and a 928, I prefer the Mann, or genuine Porsche air filters.

 

I went to Pelican and have ordered one even before I posted my question. I do have it on as I am trying to get it cranked today, will switch out filters when the other arrives. In the XJS -V12 world there was a lot of discussion about K&N and everyone agreed there was no real advantage to them.
Dan

 

The K&N in my 81 fits fine. No MAF in that car but I also have them in all my other cars. My UOA reports come back with lower silicon levels than most others I see on the various forums and in using then for close to a million miles in 9 different cars I've never replaced a MAF..

 

Pete do a white glove test,
lets see what you find.
virtually every 928 with a KnN that I see,
has the same gritty film lining the air cleaner base.

the 928s with factory filters are clean or might have a oil film but not the grit

 

Part of that could be the oil that's pulled from the filter media. If it's not showing up in the UOA, I'd guess the particles are either so small that they're being suspended in the oil and/or captured by the oil filter, so where is the concern? In most of my cars there's some modification that prevents me from running the standard airbox with paper filter. Only 2 or my 8 cars run the stock airbox for one reason or another where the OEM box no longer fits (my 81 928 and my daughter's BMW X5). My GMC pickup now has 210k miles on it. My old Saab 900 Turbo over 250k (it's my Nephew's now - original MAF / original Turbo).

People pay big money for intske porting, polishing, and cylinder honing - this just does it while you drive

 

Every car that Ive worked on with a friend over the years with a 'tuner' air filter, always had a dusty intake system.

More air without more surface area = more dirt.

 

This video was enough for me to throw out my k&n filter in my Durango in favor of a paper one again.

 

I really wished he did surface area calculations. Pleat count and depth....etc


K&N is the kind of product for people that could never read a clock with hands in school.

 

The thing I don't like about the K&N is how porous it is. If you shine a light on the background and eyeball it you see how porous it is. The principle is to use oil to trap dirt instead of inhaling it into the engine. There is no free lunch here. The only way to get more air is having a bigger filtration area. The paper elements achieve that by giving you more surface area as a result of more pleats that let more air passes through.

 

alrighty, a noob question. I understand there’s a large air filter at the back of the engine in the box with the clamps. This is the air filter right? Then there’s a filter next to the oil pressure sender I thought was the oil filter. So what’s the filter at the front of the engine inside the little box connected to their air intakes that lead to the large air filter at the back?

im looking to replace the cylindrical one at the front of the engine but the markings have worn off so I can’t tell the size and wanted an opinion as to the brand and size. I’d prefer to stick with a dry filter as opposed to an oiled one. I bought a Mann filter. I also noticed the elbow that connects to the bottom of the air filter box at front was busted off so I don’t think it was going much of anything. I fitted it back in but am assuming it’s not airtight. What effect does that have on the car? I was thinking of taking a field trip to the plumbing section of a hardware store to find an elbow that’s a similar size and then Plumber gluing it on to replace the broken one. Thoughts?