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Dread-thread: Open Air Filters

3K views 39 replies 22 participants last post by  Route246 
#1 · (Edited)
On another, rather large forum, there is a thread that is quite HOT about their opinions against some published data about open air filters being an engine killer.

While the data (most likely published by AC Delco) seems to support the fact that the exposed element filters are less efficient for a number of reasons, the popularity is extremely healthy. I am also a recent owner of the GS intake option, so the particular thread was of great intrest to me.

My impression was that the European Saabists tend to take the stance of Saab-purists, and the 'mericun bunch goes with "to each his own". While I don't think that our cars would suffer the same risks as some race-cars with very tight tolerances and expensive parts do, I would like to keep my Viggen on the road as long as possible, like most of us here do.

Has anyone experienced any catastrophical breakdowns due to the extended use of an open element (ie. K&N, AEM, BMC, ITG...), here? I assume that most of us here drive on realtively good roads (no dunes or Pikes peak...).

... sadly, towards the end of the said thread, it became a cock-fight of words and pride; not a pretty sight:sad:
 
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#2 · (Edited)
I’ve had my Saab up Pikes Peak a few times, gets very dust and turns my Saab brown. I’ve been using a cone filter for 5 years now. The outside looks pretty dirty and I have cleaned it a few times. But the inside of it looks brand new. I think the biggest question is what is getting through? A piece of dust a few microns wide is not going to do any damage, where as a grain of sand could cause some problems, but it would take a hole in the filter to get sand through it.

Did the other thread mention the micron filtration size difference between open air and paper filters? If the difference is, say, between 5 and 10 microns there is not much of an argument there, where as if the difference is between 10 and 100 microns.
 
#4 ·
I think it would be pretty hard to pin down engine failure specifically to poor filtration. I don't think I have every seen anything that would even indicate poor filtration in any of the engines I have torn down.

THe thing that most people forget is that as a filter gets dirty, it filters BETTER!!! Those little holes in the filter clog, and let smaller and smaller particles through till nothing can flow through. So for performance aspects, it is bad, but from a filtration stand, good!

In other words, in order to specifically attribute engine failure to a filter, one would have to be religious in cleaning it weekly, almost daily to even get a filter to perform poorly. That, or just run no filter at all and see where that gets you. My guess, even without a filter it would be a very long time under most normal conditions before damage occured. The oil would pick up most of the dirt, and be filtered out, or settle to the bottom of the pan.

just my 2 cents I guess.

Tboy
 
#5 ·
I wont go into the race applications, but the Oil Analysis over at BITOG have shown how poorly KN filters filter.

Does/Can this cause an engine failure ? Maybe, but doubtful for day to day driving. But personally when people have proven our intakes are good up to 400hp(stock) then why wouldnt I want the cleanest oil I can get. I had a KN panel filter on my saab until I read many articles and UOA's and decided to change back to a paper filter. I also had a oil analysis done which showed high silicon (dirt) with the KN filter, and then low silicon with a paper air filter. I feel absolutly no difference between the 2, and feel betteer knowing my oil will stay cleaner.

Like others have said, to each his/her own.
 
#7 ·
I wont go into the race applications, but the Oil Analysis over at BITOG have shown how poorly KN filters filter.
Good thing I have a J & R Filter! Haha...I personally believe that it is preference. I have seem some dyno sheets where an open air filter actually made a small difference(1 or 2 hp). I have an open air filter for the sound though. I love the WHOOSH!
 
#6 ·
Well, in my experience with the c900, the PO had put an open air element in the thing right behind the intercooler. Naturally it ran like crap on a hot day when I first got it.

So I put the airbox back in it and it ran great.

The point is, I just don't understand the open air element, "CAI" when in fact, the factory box IS a CAI -- it isolates the underhood engine heat from the intake.

Now others may argue that a CAI or open air element is more efficent, less restrictive. In fact, in the c900s, you'll find many owners plasma cutting the false inner fender wall to stick the pipe through and put the element between the inner and outter fender wall, therefore creating a new airbox to the sacrifice of placement for cruise control pump, ignition module and charcoal canister among other things.

And yet the factory box's snorkle actually pulls air from the same exact location. :confused:

I would THINK Saab would have engineered the car to make best use of the intake system -- especially with models like your Viggen -- to get the best performance. So I guess after experimenting and observing over the years (driving Saabs for 27 years...), I've come to the conclusion that Saab really did know what they were doing.

Unless you're building a 500 hp monster, I say leave it alone.

But that's just my opinion.
 
#9 ·
GM has had a recent problem with MAF failures in many of their vehicles. Some TSB's that they put out have you look for an aftermarket air filter as the first step of a driveability diagnosis.

AC Delco is essentially GM and it would not surprise me if GM used AC Delco to put out data supporting it's stance that aftermarket filters kill their MAFs, not just crappy product in the first place.

We've had several GM vehicles with failed MAF sensors and none of them have had aftermarket air filters. Hmmmmmm....

I've heard that notion that filter oil slowly kills off MAF sensors because it coats the hot wire with fine particles. Whether this is true or not, I don't know.
 
#14 ·
We've had several GM vehicles with failed MAF sensors and none of them have had aftermarket air filters. Hmmmmmm....
My stock airbox and filter were the filthiest things I had ever, ever seen. I have to clean my filter at some point but I don't think it's anywhere near as bad as the six-month-old stock filter was.
 
#11 ·
Vigge's testing is pretty valid for T7 and makes a great case that the stock filter isn't the restriction in that setup.

He hasn't tested T5, so he hasn't really made any assertions for that setup.

The filtration info is based on a pretty thorough series of tests with something like 12 different filters, but the testing was done on trucks, IIRC.

That test was pretty interesting and made a strong case that the K+N filters ACTUALLY DID allow more air through, at least for a while, but they also allowed more dirt through. Oddly enough, they eventually clogged faster and became restrictive much quicker than the paper filters they were tested against.

That's what pushed me to clean the filter twice as often as the manufacturer recommends and to change my oil pretty frequently.
 
#13 ·
I get back from work, and the click in to find that the thread has blossomed with all sorts of colors... ;)

Perhaps a Pre-filter would reduce the chances of premature clogging (to a level of inefficiency) of a "cone" type filter.

As far as silicon content of the oil goes, it would be interesting to see what amount of silicon will cause damage to a passenger vehicle. Does elevated levels of silicon degrade the viscosity of oil? Also, what size particulates begin to pose a threat to a motor and pumps? Referring to abrasive properties, of course.

From the general "feel" of the information here, it seems either is okay. My c900t that I drove for 13 years had no issues with heat, running with a K&N filter.

Oh, except for ONE trip down to Portland during 100+ temps. The motor itself was heat-soaked, and the motor ran like an unkept NA motor. The AC eventually gave up all of the freon, too. Can't really blame the filter, but it probably COULD have sucked in cooler air with the OEM "trash-can" filter housing. ...maybe it was the freon in the intake that caused the drop in performance??? nah.

This thread is turning out to be MUCH more mature and informative than the hot thread "over there", where it was a contest of who knew how much.
 
#17 ·
I get back from work, and the click in to find that the thread has blossomed with all sorts of colors... ;)

Perhaps a Pre-filter would reduce the chances of premature clogging (to a level of inefficiency) of a "cone" type filter.

As far as silicon content of the oil goes, it would be interesting to see what amount of silicon will cause damage to a passenger vehicle. Does elevated levels of silicon degrade the viscosity of oil? Also, what size particulates begin to pose a threat to a motor and pumps? Referring to abrasive properties, of course.

Thats a good question, I do not know how much silicon it takes to cause engine damage. Ill have to ask the guys over at BITOG. All i know from reading many UOA's is that whenever high silicon is noticed, people jump on it like crazy (check your air filter for leaks etc..) This is how I discovered the KN was not doing a good job for me.
 
#16 ·
I'm talking dead leaves, dead insects, gritty sand, and a layer at least an inch thick of packed dust (hyperbole of course). Which is nice because, y'know, the filter is doing its job. But looking inside the duct, there was PLENTY of dust. It wasn't really doing as well as it should have.
 
#28 ·
I ran a cone filter (JT) for several years. I have gone back to a Mann Panel Filter in the Stock Airbox (3" Ducted) for 2 reasons.

1) I never was good about cleaning it.

2) I'm trying to 'quiet' the Turbo noises.

I have not noticed any drop in throttle response etc. Its just a lot quieter
 
#29 ·
well if you went from a stock box to no filter at all do you guys think you could even tell? i think the open eir intake would be something that would effect a N/A car alot more, we have our turbo's pulling the air in and not just engine vacc.
 
#31 ·
I read/write this board also...an d if there are question realted to my tests I'am happy to answer them or do additonal test if doable.

As a general side note, please understand that hear-say, belief etc. are "oppions" and if you want to know what the difference was you need to "measrure". Sadly far too little people look into the issue (not only filters) in more detail than what the buttdyno and ears read and therefore "sandbox" is the outocme later whan the issues are dicussed.
 
#35 · (Edited)
I read/write this board also...an d if there are question realted to my tests I'am happy to answer them or do additonal test if doable...
...As a general side note, please understand that hear-say, belief etc. are "oppions" and if you want to know what the difference was you need to "measrure".
Vigge,
Can you discribe to me the repercussions of higher silicon content in oil, due to debris that passes through the induction system (oem/cone, doesn't matter) on a passenger vehicle...? While I understand that larger particles would cetainly cause damage via abrasion, but I wonder if infinitely small particles that can only be detected by examining the silicon levels of the oil could actually pose a threat to the longevity of a motor, say, for a B235R?

I've read through the particular thread on SC (K@N air filter), and found the amount of animosity to be a little more than a friendly discussion (ie. "...what part of XXX can't you understand", "What makes you think I care", etc.). It's unfortunate to see a good thread go to waste just because someone was rubbed the wrong way so they feel the need to puff-up (that "Sleeper" kid needs thicker skin).

However, I "do" appreciate the content of the thread; keep the discussions rolling :)
 
#32 ·
Did anyone else notice that Saab9-3se keeps talking about K&N oil filters where everyone else here is talking about air filters?

And i believe the K&N oil filters are probably made by Allied Signal or some other subcontracted company.

As far as the air filtering goes, I think I will stick with paper for my '91, party because I am too cheap to buy a K&N for it, and because I'm sure the Holset isn't going to have any trouble sucking air through the paper. Plus the OEM 9000 filter has some HUGE surface area to it, so my guess it that it will be a total non-issue.
 
#34 ·
If you read the original thread, he is addressing that this topic is covered on another board, on that other board they discuss KN. He then goes on to mention KN filters with other types of aftermarket air filter companies.

As I have only ever dellt with KN, I will discuss my findings and articles I have read regarding KN. I will not talk about a company or product I have not dealt with.
 
#37 ·
The people at the dealership blamed my Gensaab/BSR optiflow intake for the direct failure of my MAF.

I would take that with a grain of salt, because the car was CPO and that means they would have to comp it if it wasnt something i did....so obviously they have an interest in redirecting the blame.

Either way, supposedly my MAF failed cause of the filter.
 
#38 ·
I noticed a butt dyno gain on my 9-3 until it got to be about 90 degrees F... then it felt sluggish... I put the stock box back with a JR drop in and it got a little better... but a better IC was what finally cured the hot summer weather sluggishness.

I eventually went back to the open intake, knowing it was pretty much for sound and looks only, because the IC was doing such a great job.

my wife and I both are running open air kits with VERY LIGHT oil on the K&N on our 9-5s... again for a sporty sound... and it sits down away from the engine unlike in the 9-3.... so I am not as concerned about it getting hotter air.

if you have a OG9-3, and are opposed to open air kits, you can gain a bit of sound and probably lose some restriction by yanking the resinator box in the front bumper. :idea:
 
#39 ·
I don't look at my GS intake as a performance modification.

So I have different expectations.

My stock Viggen did not even sound like a turbo. With the addition of the intake the car sounded like it felt.

Now within a few thousand miles I replaced the MAF. So I felt that if the filter got all the excess oil out of its system I would be fine. 30k later I am on the same MAF and things seem fine.
 
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