[64speed]

Who makes the best air filter? I just bought an el cheapo on rock auto

[leeklm]

I do not have access to the link, but back in about 2005 there was a big debate on the GM Duramax forum surrounding air filters, especially because a souped up turbo diesel motor required more air flow than its typical gas counterpart.

Several members donated a couple of dozen filters to a forum member that had access to the appropriate testing equipment.

The filters were compared based on flow ability and the amount of particles trapped. In the end, the OEM Delco and Wix brands were top rated for the best mix of trapping small particles while supporting appropriate airflow.

Cheaper generic paper filters were great at trapping small particles but had poor flow characteristics. The k&n style gauze filters had the best flow, but also allowed larger particles through. Like many things, it is a compromise.

I personally run an oiled gauze filter. With the few miles I put on, and never on a dusty road, I am most worried about keeping the June bugs and small rocks out

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[64speed]

I bought a cabin air filter too. Even with shipping ROCKAUTO was much cheaper than the stores for a basic filter never mind the premium ones

[leeklm]

Oh yeah, and keeping Darby's tire rubber out of my intake when he is trouncing past me at rock falls!

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[tom s]

FYI,the 421 SD engine in my 63 Lemans has never really had a air filter on it in 22 years.I have a pair of velocity stack with a screen over it to keep rocks and little kids out of it.There is a open scoop above them.Have not done a leak down test as I dont care to know!Starts right up,will rip your head off when you kick in the 2 750s and does not use oil.Ignorance is BLISS!Tom

[dataway]

Modern vehicles are bit strange with the air filters .... my previous GMC truck had it's original filter past 100,000 miles. Still looked new, still didn't move the little vacuum "replace filter" indicator. Dealership said ... hey, it looks fine, leave it in there. Current GMC has 80K miles on it ... filter still looks like the day I bought the truck.

I think the weird serpentine air passage leading to the filter shakes out a lot of the dirt before it gets to the filter.

[Schurkey]

There's a famous "air filter test" done by a supposedly-reputable lab. Goes so far as to use "calibrated dirt". It sounds really scientific...




...until you figure out that K&N filters do so poorly because the oiled-gauze filter media IMPROVES with some added dirt. The extra dirt becomes part of the filter, which traps still more dirt. The worst thing you can do to an oiled-gauze filter is to clean it before it activates the filter-restriction indicator; or until it's got more than 1/8" of build-up on it. In normal use, the dirt builds up gradually, absorbs oil from the gauze, and becomes part of the filter mechanism; in the test, it's thrown on all at once.

Years ago, some K&N filters came with printed instructions telling you that if you had heavy build-up of dirt on the filter, you might have to add some clean "filter oil" to the clean side of the filter, but don't clean the filter until the restriction indicator showed the filter was plugging.

[David Jones]

Flat base. Gently rounded upper lid. 3” or 4” paper filter. Personally, I run a Purolator. 4” because it fits.

[242177P]

Originally Posted by Schurkey

There's a famous "air filter test" done by a supposedly-reputable lab.

If it's the one I'm remembering, the flow test also used a steady draw. Apparently
the pulses found in a normally aspirated setup actually make the K&N work better?

[Steve C.]

David Vizard did research and found the cotton media used on a K&N filter had microscopic 'hairs' that vibrated and attracted dirt particles. He mentions it within the filtration section here:

https://www.youtube.com/watch?v=ow5c...ture=emb_title

At about 11 minutes in.

But prior to that, and worth listening to, there is further information provided regarding the K&N filter. He also mentions Motorcraft filters are the best for a regular type air filter.




.

[Sirrotica]

A good portion of whatever gets past the air filter ends up in the oil, choose accordingly. On my dirt track cars, I always stacked the round stock type filters as high as the hood allowed.

Having a good air filter system on anything that runs on dirt is imperative, as it will take the rings and cylinder walls out in short order.

I've always wanted to try a filter system off a a piece of construction equipment that takes the cylindrical style filters. Typically this type of filter has a double style filter that one goes inside the main filter to catch the really fine particulate out of the airstream. The pleating on the cylindrical filters is much deeper than automotive style filters and therefore has a lot of area. The exterior can most times has a rubber nipple that can be squeezed when the engine is shut off, and it releases the powdered dust that settles into the bottom of the canister, very efficient.

These filters are commonly used on turbo diesels which have an open air tract, and flow more air volume than a typical gasoline engine does. The cotton gauze filters are typically used on dirt cars, but are less than stellar about catching the fine powder generated at dirt tracks.



Same as with oil filters, the finer the particulate that can be efficiently filtered out, the better it is for engine longevity.

[geeteeohguy]

Brad, have a friend who runs a tractor on his farm.....he had a small intake leak on one of the 4 cylinders of the tractor he was unaware of.....until it started using oil. It had sucked enough dust into the cylinder through the unfiltered leak to wipe out the rings and the cylinder wall on the one hole. And it didn't take long, either!!

[OG68]

Originally Posted by Schurkey

There's a famous "air filter test" done by a supposedly-reputable lab. Goes so far as to use "calibrated dirt". It sounds really scientific...
...until you figure out that K&N filters do so poorly because the oiled-gauze filter media IMPROVES with some added dirt. The extra dirt becomes part of the filter, which traps still more dirt. The worst thing you can do to an oiled-gauze filter is to clean it before it activates the filter-restriction indicator; or until it's got more than 1/8" of build-up on it. In normal use, the dirt builds up gradually, absorbs oil from the gauze, and becomes part of the filter mechanism; in the test, it's thrown on all at once.

Years ago, some K&N filters came with printed instructions telling you that if you had heavy build-up of dirt on the filter, you might have to add some clean "filter oil" to the clean side of the filter, but don't clean the filter until the restriction indicator showed the filter was plugging.

Replaced the factory filter on my 06 Silverado with a K&N when I bought it new.
14 years and 175K later I still haven't changed or cleaned the filter and the indicator is just beginning to show red. Figured the filter will outlast the truck.

But I use Delco filters on everything else I own.

[Sirrotica]

Originally Posted by geeteeohguy

Brad, have a friend who runs a tractor on his farm.....he had a small intake leak on one of the 4 cylinders of the tractor he was unaware of.....until it started using oil. It had sucked enough dust into the cylinder through the unfiltered leak to wipe out the rings and the cylinder wall on the one hole. And it didn't take long, either!!

Since in my later years I worked on a lot of rental and customer equipment in the material handling, and aerial lift industry, I have seen first hand equipment that as you say either had a leak in the intake tract, or was run without any air filter. It doesn't take long at all to take the rings out, and score and wear the cylinder walls. Add to that the bulk of contaminants in the air are silicon based (sand and fine powdered particulate, same components used to make grinding wheels and sandpaper) wear on the upper end happens at a rapid rate.

Now a good percentage of that matter gets past the rings and ends up in the oil, so unless you have an oil filter capable of removing particulate (by pass filter) under 40 microns your oil is going to build up into a liquid abrasive that wears the bottom end of the engine too.

I had used 2 GTOs (a 65, and a 70 RA III Judge) I bought used that were run for extended periods without air cleaners, both used a lot of oil, and had blow by because the rings were toast.

The cleanest oil and air you can get by filtering to better than stock standards will pay dividends back, over the actual cost of implementing superior filtering every time.

My regret is that in my youth, I ignored the facts and advantages of better than average filtering, I paid the cost too many times for the education, live and learn.

[Schurkey]

In my youth, I was involved every summer with the "hot-rod ski-boat" scene. The carbs were typically covered with a US Coast-Guard Approved "Flame Arrestor"; a small-diameter metal screen.

I had heaps of people tell me that "you don't need an air filter on a boat, there's no dust over the water". Then I pointed to the farm fields on either side of the river we were on. As if all the dust coming off the field stopped at the edge of the field, so the air over the river was pristine.

MY ski-boat has a plain old ugly automotive air filter housing, with a plain old automotive air filter inside. The only modification is to add the fuel-pump vent tubing also required by the Coast Guard; and to disable the hot-air flapper on the snorkel.

[Lee]

I did a dyno test, about a decade ago. The engine was putting around 470-480hp to the wheels at the time. I had a 3 different 14x3 filters and a 14x5 as well.

One of the 14x3 was a brand new paper filter, came with a big-drop nicely radiused housing, lots of space between the pleats. Another was an old paper, tightly pleated, with a wire screen in front. The other was a new K&N, and the 5" was also a K&N.

The new filter with the wide pleats was, by far, the weakest. The other 3 all performed VERY close. I realized that the wide pleats = very little surface area. The tightly pleated old filter was my biggest surprise, as it flowed plenty of air to support that much HP, even though it was old.