Whelp,

I've been influenced in the past to buy a K&N. Since then I've seen the light, and been informed by the likes of some pretty smart guys. I left one K&N in place until I got another replacement, and today I finally did the deed on one of my cars I don't drive all that much. Now it's ready to drive.

Here's a Purolater versus a K&N. The Puralator has far greater surface area, and it's "all filter". The K&N is mostly wire frame, and actually (in my humble opinion) has very little actual filter medium. It didn't take long after I held the filter up to the sky, and saw lots of daylight, to understand how they get "better flow" (better flow of dirt, in my opinion).


Since I've been with an opinion of my own, so to speak, about the K&N, I decided to "put my money where my mouth was", and I decided to burn the darn thing. Are we ready? Here goes.








Yes, this was a satisfying thing for me. It was also a "learning experience" too. After the K&N was totally torched, guess what? Most of it was still there. It's almost "all wire frame". There isn't much filter medium there, guys, it's all wire armature. I held the dirty filter up to the sun before burning it, and sheesh, I could see right through it. Therefore, I stand on my opinion that the K&N will admit more dirt into my expensive motors than the stock filter would, and since Porsche didn't go brain dead when it came time to size the air box and specifiy the filter, I really see no need (now that I'm older and wiser) to spend more and get less. If you can see through the K&N filter, it doesn't take a rocket scientist to know, driving through a dust cloud near a quarry, or driving on a dusty dirt road, would be putting a LOT of silicon into that motor.

Afterwards, I fired up the little bastard, and took a ride. Guess what? I didn't notice any difference in performance at all, nor did I expect to.

It's your car, your money, and your choice. You saw my choice. Here's a relevant thread
http://www.network54.com/Forum/426130/thread/1128071541
Regards, P

Seeing a "perfectly good" K&N go up in smoke, next to a Purolator filter, kind of makes me believe you are sincere.

This thread says a lot. In other words, you wouldn't use a K&N if someone "gave you one free".

Good show, P, and great sense of humor too.

Ken

Ha ha, but I also totally agree with you!

Autoshark

That's a pretty convincing argument, to burn one you already have, because you can see holes in it. It looks new.

I've been tempted to go with the K&N style filter, but I note the size of the air box, and the size of the actual opening leading out of the air box and into the motor, which is kind of visible in your photos, and it's quite clear the air filter is not the limiting factor here. Any claim of additional horsepower in a 944 is a joke.

Jay

I had to laugh, seeing someone set one on FIRE, ha ha ha.

Roger

I copied this from one of the threads here, but I'd seen it somewhere else too. So if people are willing to suck in dirt, why not just run with open velocity tubes like the old CAN AM racing days? You know they wanted all the power they could get, and they didn't care if they sucked in anything, as long as it wasn't a pebble. Those engines were torn down after EACH RACE.

I looked at your photos again, P, and it's quite apparant the cars have limitations that are far beyond the filter. In other words, the internal ports that direct air to the motor, are far more constrictive than what will go through that big air box on a 944, and the even bigger air box on the 928. Why people are willing to drive around with inferior filtration on expensive machinery is beyond me.

Here is that passage that makes so much sense to me:




"I worked for race teams for years. One Toyota Atlantic teem I worked on the driver thought the car was lossing power from the start of a race to the end. So we did leak down checks when we got new engines in. 3% leak down- New. At the end of a race we checked it again and we got 29% leak down. So we sent the head to get the valves done and checked the leak down when the head returned. 4%- Leak down. At the end of the next race 31%- leak down. So we put three dabs of grease down streem of the air filter. "K&N" The next engine came in with 3%-leak down new. And at the end of the race 32%- leak down and the dabs of greas were full of grit. So we changed the filter to a oiled fome filter. 3%- leak down new and at the end of the next race? 18%-leak down. Better still not good. So we made a new air box and used a Mustang GT stock air filter. 3%-leak down new at the end of the next race? 1%- leak down yes I said "1%". The rings bed in and the engine seals up. We went from changing a engine at 300 miles with 29 to 34% leak down to. Changing the engine at 800 miles with 7% leak down.

So the bottom line is. You mite gain a littel more power (1 to 2hp) but it will not last long and befor you know it you will have a LOT less.
I work on 944s only and when I tare down a 944 engine that has had a K&N filter the cyclenders have a LOT of scores from dirt that got through the filter.
If you dont beleve me do the grease test your self. Take out the filter and put a dab of grease in the air box. Then put your K&N filter in and dive the car for a few weeks and pull the filter out and check the dab of grease.

Good Luck Mike F "

That's the most hilarious post I've seen in a long time. So disgusted with a car part that the guy sets it on FIRE, ha haha hahahahaha

Gene

1985 automatic

I found this by "deep surfing the net". I have removed the email addresses and from these posts, so as to not to have these guys get unwanted email.

There seems to be a lot of 928 owners that don't think much of the K&N air filter







From: Walt
Sent: Monday, January 22, 2001 2:22 PM
To: 928
Subject: [928] Re: Comprehensive set of dyno tests

----- Original Message -----
From: David
Subject: [928] Re: Comprehensive set of dyno tests


> Tom,
> Am I reading that the K&N produced a loss over the stock filter?
> And yes, I'm aware that isn't most relevant part of your research.
> David W Moody Jr

I've been posting K&N filter testing results for well over two years now,
indicating that there is ABSOLUTELY NO POWER INCREASE to be realized by
installing a K&N on a 928. Matter of fact, the K&N will allow more
particulate to pass through, making it more harmful to the engine. Due to
less filtering action, it may somewhat change the tone of the motor, and
that may lead people to believe they are getting more power, but they're
not. Everytime I'd post this, I'd receive a collective
up-the-side-of-the-head-whopping from all the K&N lovers, claiming that they
could feel a seat-of-the-pants power increase.

Let's see now, K&N claims a 15% increase in power, that would bump an 88 S4
from 316 hp up to 363 hp.

What? You don't believe it?

As I've mentioned many times before - - -their claimed increase in power was
developed by their marketing division, not their engineering division.

Live and learn.

wk


----- Original Message -----
From: Jay
To: 928
Sent: Monday, January 22, 2001 3:08 PM
Subject: [928] Re: Comprehensive set of dyno tests


> Shouldn't rob power unless it is so oil saturated that it is restricting
> flow.
>
> This K&N myth is just the best. They say "traps more and smaller particles
> than stock" then they say "less restrictive". Must be one of those Physics
> loopholes we always hear about.
>
>
>
> Jay K.
>


From: Mark
Sent: Monday, January 22, 2001 4:33 PM
To: 928
Subject: [928] Re: Comprehensive set of dyno tests

I am going to stick my $.02 worth into this new finding. I think there was a
HP loss due to the fact the K&N filter flows more air (98% increase
according to one ad) creating a lean condition that could not be compensated
for by the stock mapping system. I think with proper mapping there should be
increased HP. It would be interesting to prove.
Mark Baistrocchi
88 auto/w sunroof and no TBF related problems



From: Walt
Sent: Monday, January 22, 2001 5:07 PM
To: 928
Subject: [928] Re: Comprehensive set of dyno tests


Sorry, but the amount of airflow being sucked through a clean filter is
limited to a function of displacement and RPM. The motor can suck in only so
much air, and it ain't gonna take 98% more.

wk



> -----Original Message-----
>
> Does anyone have any hard evidence that K&N air filters are
> better or worse than the OEM Air filter?


From: Jay
Sent: Tuesday, July 31, 2001 10:36 AM
To: 928
Subject: [928] RE: K&N vs OEM Air Filter.

Nick,

The below is my personal bent. I have never tried or wanted to try K&N for a
couple reasons.

Filters are rated in a couple ways but one of the big variables that
manufacturers measure is flow loss or pressure drop. Filters with larger
pressure drops NORMALLY trap more crud and restrict the flow more. Filters
with low pressure drops can let in more air but at the expense of not
filtering as much crud. More crud means more wear relatively. Each engine
has size particle that it can pass through without hurting anything greatly.
This size particle is related to the lubrication film thickness of the
majority of the fits in the engine. If particles larger than the film
thickness get through the moving parts ride on the particles and not on the
oil film like they should. That is bad. You can be rest assured that the
engineers at Porsche considered this when designing the size of the filter
element and it's pressure drop and the particle size that it filters. You
can also be rest assured that the people at K&N didn't consider anything but
their profits.

So the hard evidence that K&N filters are worse is that they market more
airflow than stock. Guilty by their own specification.

My opinion is that a K&N filter is worth about as much as a coffee can sized
exhaust outlet hose clamped onto a 1" muffler outlet. Also, this particular
subject is odd because after saying it it sounds like I have the opinion
that aftermarket supposed upgrade parts are all bad. Not the case at all.
There are a ton of great upgrades. This just isn't one of them. When you buy
you just have to understand what you are getting and what compromises you
are making. This list and other sources are great ways to find out about a
potential upgrade. It is your job to collect all of the opinions and make a
decision for yourself. Or you can just ask Wally He tends to always know.

Hope this helped.

Jay
79 US 5ish speed (paper oem filter)



From: Tom
Sent: Tuesday, July 31, 2001 3:07 PM
To: 928
Subject: [928] Re: K&N vs OEM Air Filter.

Just a couple of personal observations on the filter issue....


I have used both in my 87S4 A/T. While at the recent bracket drags (Pac
NW) I was running around 14.1 secs in the 1/4 mile. Swapped out the stock
filter for the K&N (freshly cleaned and oiled) and ran 14.00s and
eventually down to 13.98.

The dyno would not be a good way to differentiate any filter
advantage/disadvantage since the airflow into the engine is nowhere near
what it would be at speed on the road...

My feeling is that since an engine is basically an air pump, then getting
more air in and more air out is an advantage. I believe the K&N lets more
air in (of course that means more particles and there are also other
restrictions on air inflow --MAF/intake for example...). It did allow me
to gain 0.1 secs in the 1/4. Worth it? To me it was.....

I drive my car about 60% daily use and 40%track (not many miles this
year). Ideally I would use the stock filter for the daily driving and put
the K&N in for track of performance. Of course I haven't switched back to
the stock one yet.......

Also, while cleaning out my K&N (it was very dirty) in looked at the size
of the grit that was being washed out of the filter. From a geologists
perspective the grain size was on the order of a very fine sand to silt.
If the filter can stop silt from entering then thats fine by
me.....(coarse silt has an average diameter of about 0.016 mm). I just
keep on top of my oil changes and watch out for those boulders that will
take out my lowered S4s oil pan. >..

I guess the real question is has anyone documented significant wear of the
valves or cylinder walls that can be attributed to "dirty" air?

Later,
Tom



From: Richard
Sent: Wednesday, October 31, 2001 1:59 AM
To: 928
Subject: [928] Re: K&N filter killing my MAF ?

How long has it been since you cleaned and re-oiled the K&N?

Several Boxster owners have reported killing their MAF by
having excess oil on the K&N and the oil migrating to the
MAF. Not much luck cleaning the MAF, replacement seemed to
be the only fix.

Richit
90 GTless

I just discovered this thread and first, I have to laugh, becuase someone out there has a great sense of humor. Secondly, the point is so very well taken, and I totally agree with the outcome.

Rick