Why Are Air Filters Important?

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I'll tell ya...

The air intake system is the only connection between your engine's crankcase and the outside world. It's the only way outside contamination can make it into the engine. It's important to long engine (and lubricant) life that the air intake system be completely sealed and use the highest efficiency filter possible... one that allows the engine to reach it's rated power. Outside contamination begets increased wear. I contend that a high efficiency air filter is a higher priority than a high efficiency oil filter... if you have to pick one over the other. For myself, I would sacrifice a little upper end power for a high efficiency filter. Of course, if you face the quandary of not enough airflow to meet power requirements, you could consider increasing the filter area.

Yes, a higher efficiency filter will show more restriction sooner than vice versa. So what? That's what a filter restriction monitor is for. In any case, the fuel economy is not effected on an EFI car due to air filter restriction until the engine can barely run and a small power loss is usually not noticed in everyday driving. Lead-foots would be more conscious of this.

So, buy the highest efficiency filter you can (look for 99% plus on coarse dust tests, which is about 97% on a fine dust test... a rare spec to see). Make sure it seals well in the housing and that there are no leaks anywhere else in the system. Install a restriction gauge and replace the filter only when it reaches the right restriction (variable, about 10" of water, 2.5kpa is the generic number). If you were performance oriented and you saw the power coming off sooner, you could change sooner. Or, if you are economy minded, you could go higher. It will vary from engine to engine, depending on how you use the vehicle and how much filter area it has.
 
Great post Jim...alot of people I know skimp on their air filter. I will forward this to them to read. I wish we had a list of bitog approved filters..Good to see you around buddy.
 
Welcome back Jim. I frequently quote and link some of your prior posts on AFs (efficiency and loading relationship) and OFs (holding capacity). I know you are big fan of AF restriction gauges. Good see a new contribution from you here.
thumbsup2.gif
 
Where might the best information be for this? Such as independent studies or SAE papers etc.?
Information that proves dirt entering the via the air intake is a major [perhaps the biggest] contributor to engine wear and secondly, that a used filter [not yet overly restrictive] is more efficient.
 
Originally Posted By: Shellguy
Great post Jim...alot of people I know skimp on their air filter. I will forward this to them to read. I wish we had a list of bitog approved filters..Good to see you around buddy.

True and a lot of people pay a lot of money for a K&N filter air intake kit, or whatever they call it. [The kind of air filter you apply their oil to and wash and reuse] to increase HP and have no clue what kind of damage they're doing to their engine. Expensive in the case of K&N can be bad too.
 
Originally Posted By: demarpaint
True and a lot of people pay a lot of money for a K&N filter air intake kit, or whatever they call it. [The kind of air filter you apply their oil to and wash and reuse] to increase HP and have no clue what kind of damage they're doing to their engine. Expensive in the case of K&N can be bad too.

Sorry, but have you ever heard of a K&N causing an engine failure?

Fried MAF from over-oiling, sure. Maybe a K&N isn't 99.9% efficient at a half micron, I'll give you that... But over the course of typical ownership, what harm does it really do? Heck, even extended ownership.
 
I've got a friend with a Saab 9-4, and he has run a K&N since new. He is approaching 300,000 miles, and the car runs great.

That said, the K&N is not my cup of tea. I like a high efficiency paper filter that is easy to change, and I don't like the mess or headache of oiling a filter.

I doubt a K&N, properly maintained and used, has caused an engine to wear out significantly sooner than it would have with a paper OEM filter.
 
Originally Posted By: rooflessVW
Originally Posted By: demarpaint
True and a lot of people pay a lot of money for a K&N filter air intake kit, or whatever they call it. [The kind of air filter you apply their oil to and wash and reuse] to increase HP and have no clue what kind of damage they're doing to their engine. Expensive in the case of K&N can be bad too.

Sorry, but have you ever heard of a K&N causing an engine failure?

Fried MAF from over-oiling, sure. Maybe a K&N isn't 99.9% efficient at a half micron, I'll give you that... But over the course of typical ownership, what harm does it really do? Heck, even extended ownership.


I read UOA's they typically show extra wear, that's good enough for me. You've been around it has been discussed here many times, the general consensus has been they're not good. And it also fits into this topic perfectly.
 
Originally Posted By: WobblyElvis
Where might the best information be for this? Such as independent studies or SAE papers etc.?
Information that proves dirt entering the via the air intake is a major [perhaps the biggest] contributor to engine wear and secondly, that a used filter [not yet overly restrictive] is more efficient.


So you doubt it? How can you? It's a closed system, the only way outside dirt can enter is via the intake system (well, except for ancient cars with road draft tubes). Internal normal wear and the resultant particulate contamination is a separate issue but that wear is effected, can be greatly effected, by how much dirt gets by the rings.

If you go back and look at my older posts (it will be back before 2014) I cite most of this. But yes, it came from various peer reviewed papers. See the synopsis article I did that is linked, which is a layman's overview.

Air Filters
 
Pantyhose worked well when Mt. St. Helen's blew in 1980. I live in the desert (large sandbox) and installed a Snorkel. People make fun of me because they think it's for water. It's because of dust. Ever going wheelin with a bunch of 4x4...the dust is horrid. Cyclonic filters are the best for worst conditions...



Respectfully,

Pajero!
 
Originally Posted By: Jim Allen
Originally Posted By: WobblyElvis
Where might the best information be for this? Such as independent studies or SAE papers etc.?
Information that proves dirt entering the via the air intake is a major [perhaps the biggest] contributor to engine wear and secondly, that a used filter [not yet overly restrictive] is more efficient.


So you doubt it? How can you? It's a closed system, the only way outside dirt can enter is via the intake system (well, except for ancient cars with road draft tubes). Internal normal wear and the resultant particulate contamination is a separate issue but that wear is effected, can be greatly effected, by how much dirt gets by the rings.

If you go back and look at my older posts (it will be back before 2014) I cite most of this. But yes, it came from various peer reviewed papers. See the synopsis article I did that is linked, which is a layman's overview.

Air Filters


Never said I doubt it and it makes perfect sense. I just to learn from the best sources I can, not hearsay.
Thank you for the info.
 
Originally Posted By: Pajero
Pantyhose worked well when Mt. St. Helen's blew in 1980. I live in the desert (large sandbox) and installed a Snorkel. People make fun of me because they think it's for water. It's because of dust. Ever going wheelin with a bunch of 4x4...the dust is horrid. Cyclonic filters are the best for worst conditions...



Respectfully,

Pajero!


Yep! I have had snorkels over the years and they really added to filter life. Cyclonic too. The late-great Bum-Vee had an adapted 600ci tractor air filter with a cyclonic feature to it. It worked very well for the heavy coarse stuff. One of the best mods I made for that truck.
 
Originally Posted By: WobblyElvis

Never said I doubt it and it makes perfect sense. I just to learn from the best sources I can, not hearsay.
Thank you for the info.


Got it! I haven't been around for a while but I think I had a pretty good rep for not proffering heresay... but you can be the judge of that after you fingers have done the walkin'.
 
Jim,

What are your thoughts / findings on the new Fram Ultra air filters, and Purolator discontinuing their pre-oiled PureOne air filters?
 
I don't know much about the new Ultras but I think generally speaking Fram makes top drawer air filters. Don't know much about the Puros either, coming or going. I am a few years from having to replace any filters, so I am not engaged in a search at the moment.
 
Originally Posted By: demarpaint

I read UOA's they typically show extra wear, that's good enough for me.


And VERY high silica levels = more dirt in the oil

Originally Posted By: Jim Allen
(well, except for ancient cars with road draft tubes).


Even those operated under semi-positive pressure, except the old chevys with unfiltered "louvers" in the valve cover
 
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