Air filters have a much more demanding job than oil filters do because air filters must filter all of the air in a single pass whereas oil filters have the luxury of re-filtering all of the oil in the crankcase many times each hour. In this post I'll discuss the performance of the stock FA-1750 air filter, the AIS air filter, and the stock FL-1995 oil filter.

Here's what air filters in general must contend with. As shown below the micron or um size particles in the atmosphere consist of windblown dusts, pollens, sea salts, and other natural sources of particles. Particles larger than about 60 um (diameter of a human hair) tend to settle out of the atmosphere so that particles in the 1 um to 60 um range constitute the Total Suspended Particulate matter in a typical atmosphere. Of course if you're in a wind storm like we're currently having in Amarillo then you can forget about particles larger than 60 um settling out of the atmosphere!

[img]http://h1.ripway.com/ernesteugene/DG4/fine_particles.jpg [/img]

According to this site... http://www.bestsynoil.com/filters_filtration/amsoil_air_filters/amsoil_eaa_air_filters_ac.htm ... "There are over 400 tons of suspended dirt and other contaminants in a cubic mile of air over a typical city. The concentration can be even higher in rural areas where there is frequent travel on unpaved roads. The dirt and contaminants drawn into an engine are the leading cause of engine wear."

For the purpose of this discussion I'm defining this "400 tons of suspended dirt and other contaminants" as dirt and that works out to be 800,000 lb of dirt in 1.47x10^11 ft^3 of air which works out to be 5.4x10^-6 lb/ft^3.

As I discussed here... How much CFM does an engine need??? ... https://www.ford-trucks.com/forums/showthread.php?t=843304&goto=newpost ...a tuned 7.3L producing 300 "smoke free" FWHP consumes 15.9 gal/hr of fuel and 446.7 ft^3/min of air. This means when you're towing a heavy load up a steep grade requiring 300 FWHP that your air filter is ingesting (446.7 ft^3/min )(5.4x10^-6 lb/ft^3)=2.4x10-3 lb/min of dirt which is 0.14 lb/hr of dirt. So for every 10 hours of high HP operation in this defined environment your air filter ingests 1.4 lb of dirt!

Well it turns out that 1.4 lb of dirt is all that a stock FA-1750 air filter can hold before its restriction increases to a level indicating the filter needs to be changed. If you've spent this 10 hours of maximum HP operation towing grades in direct gear at 60 MPH the change interval is 600 miles but if some of the time was spent in lower gears the change interval is even less than 600 miles!

An AIS holds about 3 times more dirt than a stock filter does which is one reason why it's a good choice for towing which involves a lot of high HP operation but still that's an AIS filter change for every 1,800 miles of maximum HP operation???

Well just Goggle "suspended dirt and other contaminants in a cubic mile of air" and see what you can come up with. Either there's an error in my calculations or you just can't believe everything you read on the Amsoil web site because I never changed my AIS nearly that often and I did a lot of near maximum HP operation!

I've seen EPA "clean air" specifications that are 100 ug/m^3=6.3x10^-9 lb/ft^3 which is almost 1,000 times cleaner than the 5.4x10^-6 lb/ft^3 I calculated from the Amsoil number. Maybe Amsoil meant 40 tons and not the 400 tons they stated? Why is Amsoil even using "a cubic mile of air over a typical city" as a measure because clearly there's more dust nearer the surface than there is a mile high?

For the sake of this discussion I'll use a number that's a factor x10 lower than the Amsoil number and that means 5.4x10^-7 lb/ft^3 of dirt and that works out to 1.4 lb of dirt for every 100 hours of maximum HP operation and that means changing a stock filter every 6,000 miles and changing an AIS filter every 18,000 miles.

If you're cruising along at 100 FWHP these change intervals are almost tripled but not quite because at lower HP the AFR is higher than at maximum HP so the CFM isn't quite a third less. Under typical cursing conditions you might need to change a stock filter every 18,000 miles and an AIS filter every 54,000 miles.

So based on the above lets assume an air filter ingests 1.4 lb of dirt in 18,000 miles and then calculate how much of this dirt passes through a stock filter and into the turbo. The "Dirt Filtering Efficiency" of a stock filter is 99.76% which means that 0.24% of the ingested dirt passes through the filter and that means 3.4x10^-3 lb of dirt passes into the turbo every 18,000 miles and in 108,000 miles after 6 changes of a stock filter 0.02 lb or 9.1 grams of dirt has passed into the turbo.

The Donaldson Power Core Ultra Web technology blue media used in the AIS has a "Dirt Filtering Efficiency" of 99.97% which means that only 0.03% of the ingested dirt passes through that filter and this means the stock filter passes a factor of x8 more dirt than the AIS does so after 108,000 miles and 2 changes of an AIS filter only 0.0025 lb or 1.1 grams of dirt has passed into the turbo from an AIS!

Well if I was a turbo I'd know which filter I'd rather have in front of me and I'd be down right terrified if I heard my owner talking about installing one of the many popular filters that only have a "Dirt Filtering Efficiency" in the 93% to 95% range like two of the filters shown in this table.

[img]http://h1.ripway.com/ernesteugene/DG5/ISO5011.jpg [/img]

Compared to an AIS with its 99.97% efficiency the filter with the 93.44% efficiency passes 6.56% compared to 0.03% for the AIS and that's a factor of x219 more dirt or 241 grams of dirt in 108,000 miles vs 1.1 grams for an AIS and that's more than enough dirt to choke even a mighty 7.3L horse of an engine.

Most of the dirt which passes through the air filter and into the turbo makes its way through the intercooler and into the cylinders and then some of that dirt makes its way past the valve stems and piston rings and begins to accumulate in the 4 gallon oil reservoir in the crankcase. Even though most of the dirt that's ingested by the engine during the intake strokes just goes right back out again during the exhaust strokes it does do some damage along the way.

So some of the dirt that's passed by an air filter winds up in the 4 gallon oil reservoir in the crankcase and it's the oil filter's job to filter out this dirt along with the various other contaminants that accumulate in the oil. Particulate matter that's 30 microns=0.001" and smaller is of particular concern because these size particles can easily infiltrate between moving parts with clearances of 0.001" and greater and do damage.

For example the typical valve stem to guide clearance of up to 0.003" on the intakes and up to 0.004" on the exhausts and the vertical clearance between the ring and the ring land in the piston is up to 0.004" and when you consider the 2,000 psi combustion pressures involved it's not hard to see dirt blowing past these clearances and dirt is also carried along with fuel wash down.

So now the oil filter goes to work and the only specification I can find on the stock FL-1995 filter is that on a single pass its filtration efficiency is 68% for 20 micron particles. When compared to the 99.76% single pass efficiency of the stock air filter this 68% efficiency seems very low but consider that the 2 pass efficiency of the stock oil filter is 89.76% and the 3 pass efficiency is 96.72% and the 4 pass efficiency is 98.95% and the 5 pass efficiency is 99.66% and the 6 pass efficiency is 99.89% and even though these net efficiencies assume that no additional contaminants are entering the oil supply as the various passes through the oil filter are being accomplished it's clear that an oil filter can use multiple passes to improve its net filtration efficiency.

The oil filter equivalent of an AIS is the Fleetguard LF-3974 (Stratapore) filter which I switched to soon after it was introduced because it provides a higher filtration efficiency of small particles less than 20 microns but still has the same flow restriction of a FL-1995.

Well as they say an engine's happiness depends on clean air, clean oil, and clean fuel and the stock fuel filter is probably the weakest link of the 3 but all can be improved by appropriate upgrades. If someone can come up with the gal/min flow of the LPOP at some reference RPM or how long it takes to pass all 4 gallons of oil through the oil filter please post that information.

Also if anyone finds additional data concerning the dirt content in the atmosphere please post it. Posting your change interval for a stock filter or an AIS would be helpful especially if it's based on a restriction gauge reading which allows for an estimate of the amount of dirt captured by the filter.

 

For some reason my pictures won't display in an original post but they will in a reply to my own post???

 

Very interesting that the 6637 isn't tested/compaired.

 

You know, I've been waiting for something like this, Gene. You want to see a *perfect* reason to get rid of the stock filter set up (and stock CCV)? Take a look at this:
https://www.ford-trucks.com/forums/8...s-picture.html

You have called the stock setup perfectly good as designed, and that is what this guy had. It could have (and may still have -- the jury is still out) cost him his engine. Sorry, but that HORRIBLE stock intake has to go. ANYTHING is better that that POS...

 

Wow, that's a bunch of data!! I have a peanut for a brain, but it all makes sense to me. How's the CAT treating you? Thanks for another post Gene!!

 

So if I post some pictures of a wrecked F350 where some careless driver ran off the road and hit a tree that would prove that all stock F350s are unsafe and that they all need to be upgraded???

If you could highlight and quote back to me where any of my statements are not factual or where I've made errors in any of my calculations then we'd have a basis for a point counter point discussion of the matter but I don't see where posting the aftermath of someone's obvious incompetence proves anything except that some people shouldn't be allowed to own a nice truck like the 7.3L is and it is in fact a very functional truck just the way it came from Ford!

As I've posted many times in many places...

 

So how does the continuous dirt injestiont affect the initial pass vs. multiple pass on the oil filter? 99.89% on 6 passes doesn't seem that great if there is also a percentage of oil containing the 68% filtration rate. Have you factored the average filtration rating yet? Since the bypass filtration set up filters a small percentage of oil per pass, how does it's average filtration rating compare to the stock set up?

Also, by looking at the intake wheel on the turbo, it appears that most of the molecules entering the turbo come in some contact with the wheel, buy you seem to have a way of telling us that appearances and calculations don't match. If we take your 241 grams of dirt in the example above, how much of this actually affects the wheel in the turbo? Will the wheel not show the effects of dirt before the rings or internal components of the engine? Also, any idea what the acceptable amount (i.e. non harmful) amount of dirt ingestion is?

 

Yeah, sure. Nice reply. You're awfully crotchety these days.

I can say that a "vigilant K&N filter owner" would be okay with that filter, too. But I wouldn't suggest it. I WOULD suggest that the stock box is a complete POS and unless *YOU* can prove that it's not (you applying Vasoline to it is a perfect way of agreeing with me, BTW). The point is you shouldn't have to do all that. It should work the way it was meant to: install it and change it when it's dirty.

 

I for one do not like the rather crude looking install of MOST (but not all) 6637s.
I have been running a PUROLATOR PURE ONE drop in panel filter in my stock air box of my 99.5 for just over 15k miles, and also a PUROLATOR PURE ONE oil filter as well, and just recently got a Blackstone labs report on my oil:
They said everything was good and doing a nice job including my air filter-(which, btw they had no idea what I was running) so in about 5k more miles I will buy anouther PURE ONE air filter and install it into my stock air box.

 

I, for one, belong to the 'stock/factory' is best for efficiency, economy, and most importantly for me, longevity. I figure the factory has spent a great amount of time and effort researching and testing...............with the exception of our stock airboxes.

I am considered '****' by some, (usually those that are sloppy and disorganized). So in the past year I've owned my '01 Crew, I have checked my filter, changed it once, but did not check the turbo side of the box. By the way, I was extremely careful in seating the filter, and ensuring there was a very good seal on it as I set the lid on it before clamping.

Well, since I've been lurking and reading a lot here on FTE, I decided to pull the lid and filter out, and check further inside. Well, drawing a finger on all the surfaces on the turbo side of the box and in the tube yielded a consistent coating of fine grit. Luckily, without spending too much time, the turbo vanes seemed to look ok. I was in a hurry at that point because I went straight to Napa for a 6637, and Lowe's for a coupler.

Amazing that I was actually able to feel a difference off the line. Can just imagine what it might do for mileage at freeway speeds. I am completely sold on the 6637 set up, and looking forward to pulling it off in a couple weeks to check inside the tube.

While there is some truly impressive data around regarding filtration, I am only sharing my own experience with my airbox set up.

Awesome rigs we have, and this is an equally awesome forum to keep 'em strong.

 

Eugene,

this is the first time that I am going to disagree with you, your analogy is flawed because a careless driver driving off the road is not the same as a component failer at no fault of the operator, so if a steering component failed and the truck left the road and hit a tree, then yes there is an issue, the issue with the airboxes is not primarily due to operator ineptidude but instead largely due to faulty engineering (I still think this truck is the best truck out there)

 

If the factory air box is so bad, then how do you explain the thousands upon thousands 7.3s going strong with 200,000+ miles on them? And no dusting of turbos? If I'm reading Eugene correctly, he's suggesting that those with troubles either have not taken the time to properly install the filter and seat it well on the lower part of the box and get the lid on just right, or have failed to observe a damaged filter box. There are 3 PSD trucks in my family, one with 170K and the other two on an IL farm (talk about a lot of dirt in the air) with well over 200K and the factory boxes are working just fine. Having said that, on mine I did recently bolt in the Ford AIS just because.

 

Mine started to leak around 240k.

 

I did some more internet searches looking for testing data on the 6637 and I came across this "gem" from Dale Isley who's the vendor for the Tymar intake. A potential user asked Dale why his "Tymar air filter" which most know as a 6637 only has a maximum rating of 470 CFM by the OEM?

Well Dale responded to this straight forward question with enough convoluted meaningless double talk nonsense as to make any politician proud! I've given the link so please read his entire answer and judge for yourself. I've quoted a few things that seemed to be actually saying something and added my own C=comments.

TYMAR CFM ? Dale I ?
TheDieselStop.Com Forums: TYMAR CFM ? Dale I ?

Q: "...What is the CFM rate for the TYMAR air filter ? I think the CFM requirement for a stock PSD is about 600 CFM. The Baldwin PA 2818 flows 470 CFM max. They list it as a Donaldson B085011 which is the same. Dale is this correct ?..."

A: "...Most testing will not be done at the levels of intake volume that a PSD flows, especially when you start modifications..."

C: This is a totally untrue answer because the ISO-5011 Air Filtration Standard clearly states that any air filter that's intended for use on any 7.3L turbocharged diesel which makes its maximum HP at 2,800 RPM should be laboratory tested at an "intake CFM" of 628 CFM!

Here's the equation that's used in the ISO-5011 standard and for any turbocharged diesel the VE is specified to be VE=1.75...

CFM={(CID)(RPM)(VE)}/{3,456}={(443.1)(2,800)(1.75)}/{3,456}=628 CFM

...note that the ISO-5011 testing done on the stock FA-1750 filter and air box was done at 628 CFM for the dirt loading portion of the test and that an initially clean filter was tested at CFMs as high as 929.8 CFM!

A: "...For those reasons, I like to compare restriction readings when comparing filters while the filter is installed in the applicaiton because it will provide you with more realistic data to apply..."

C: ...Here he's claiming... "...Since the PSD has a turbo and volume will vary if the compression (boost) is varied, cfm amount can vary..." ...that because a PSD has a turbo and the lab doesn't that laboratory testing under controlled airflow conditions isn't realistic or reliable and this claim is utter nonsense!

A: "...You also need to look at the filtration efficiency when comparing filters. A less effective filter will usually allow more flow because it does not impede flow to catch the smaller particles. In race applications you will want an engine to last as long as the race lasts, but in performance applications you want the filters to meet at least the OEM required amounts (and hopefully above). Generally, two filters with the same media size (media size is not filter size. It is the actual size of the media in cubic feet that is used in the filter) and the filter that flows more will have a lower filtration efficiency..."

C: Well finally a mention of "Dirt Filtering Efficiency" and that any appropriate substitute filter should at a minimum... "meet at least the OEM required amounts" ...and not pass any more dirt into your engine than the ISO-5011 tested 99.76% "Dirt Filtering Efficiency" of the stock FA-1750 filter but then there's no further mention of how much dirt a 6637 actually passes into your engine.

Based on my research to date I've come up with an "estimated" answer to the above question but for obvious reasons I'm reluctant to post it. That's why I offered $20 to get the ball rolling to test a 6637 in an ISO-5011 certified laboratory so the results can be posted to warn newcomers before they install a 6637 on their trucks!

Now lets compare the Dale Isley evasive double talk about how much dirt a 6637 might pass into your engine with what's on the K&N website which I'll quote and then comment on...

K&N: "...We subject a sample of our filter designs to this test procedure using Coarse Test Dust, which includes particles ranging in size from less than 5.5 microns to 176 microns..."

C: So K&N employs a "Coarse Test Dust (5.5 microns to 176 microns)" and the stock FA-1750 filter was tested using an ISO-12103 "standardized dust" which has a specified distribution of particle diameters ranging from (0.5 micron to 150 micron) and the peak of the particle distribution curve is at a 60 micron particle diameter.

Well testing with "Coarse Dust" clearly results in less "Passed Dirt" and this in turn results in an artificially inflated value for "Dirt Filtering Efficiency"! Also K&N fails to mention at what CFM the "Coarse Dust" was introduced into the airstream. A well known method of "cheating" on a test for "Dirt Filtering Efficiency" is to feed the dust into the airflow at a CFM that's less than the 628 CFM required in an ISO-5011 certified test for "Dirt Filtering Efficiency".

K&N: "...Those tests demonstrate K&N air filters generally achieve overall filtration efficiency in the range of 97% - 98%, while some of our air filter designs have achieved levels as high as 99%. The fact that our air filters at times reach overall filtration efficiencies as high as 99% while maintaining high airflow is a testament to the quality and capabilities of our oil impregnated cotton air filter medium..."

C: A 98% "Dirt Filtering Efficiency" means that 2% of the dirt passes into your engine compared to only 0.24% for a stock FA-1750 filter and only 0.03% for an AIS! Said another way the K&N passes a factor of x8 more dirt than a stock FA-1750 filter and the K&N passes a factor of x67 more dirt than an AIS!

Please note I used 98% which is at the upper range for the K&N, I didn't adjust for the "Coarse Dust" part of the K&N test, or account for the lower than 628 CFM that they probably tested at. At least K&N is honest enough to provide sufficient factual information so that any potential customer can know in advance that they'll be dusting their engine big time if they switch from their stock FA-1750 filter to the K&N!

How about this idea. We'll start an FTE "office pool" to guess the "Dirt Filtering Efficiency" of a 6637 and the entry fee is $25 with $20 being used to pay for an ISO-5011 certified test and 5$ paid out to a favorite charity in the name of the winner just to keep things legal. You can enter as many times as you want and each guess of "Dirt Filtering Efficiency" must be to the one 100th percent!

 

See post no. 10. And if having to put petroleum jelly on the lip of the filter is considered a well engineered box, what's bad? My wife's truck (Mitsubishi Raider DuroCross) has a very similarly designed box to ours, complete with clips & everything. It will be going bye-bye soon as well. Here's the stock box:


Something like this is what'll be going in: