One thing to remember about the 6.0 is it has 4 valves per cylinder. It may be smaller in displacement, but it has much greater capacity to breath. Coupled with a slightly higher operating RPM and the bigger air cleaner becomes a necessity.

 

I was just comparing the filter elements (not the engines) to see which one might be able to flow a given amount of air with the least restriction. I still think the 62% longer flow channels on the 6.0 could very easily cause more restriction than the 37% more area gets back.

Regarding volumetric flow differences which depend primarily on displacement and rpm, at 2000 rpm (where I cruise) the 7.3 with its 22% more displacement might easily pump more air than a 6.0 at the same rpm. I think the 4 valves become more important at higher rpms.

 

If you want to see a side by side comparison of the filters, there is one in my gallery.

If the powercore filter works as it is advertised, the greater depth of 6.0 filter should result in lower restriction due to greater actual filter media surface area. The 6.0 system is also a much more liner airflow design, the AIS makes the air take at least 3 90* turns while the 6.0 filter is essentially straight through linear flow. I don't think there is any way the AIS could flow more air than the 6.0 system based on my experiences with both.

 

First, back to the original issue at hand..."I replaced my 6637 with the stock airbox b/c the drone was getting to me. Slight increase in EGTs but power was about the same, maybe dropped a bit but still able to pull the same hills with no problem."....."Then I replaced the stock airbox with the AIS"...Then saw higher EGT and lower boost and asked if the AIS was to blame. So the real comparison being asked about was the AIS versus the stock airbox, and I'm quite sure the AIS is better in all regards.

I didn't bring up the 6.0 except to respond to the question if Banks tested it or the 7.3, and I think I heard that both elements were tested and the 7.3 had less restriction. I think these were simple flow tests of just the elements in a test rig that measures delta P for various flow rates. My previous analysis and some additional analysis here, is just for the elements. I agree that the rest of the installation (air box, inlet tube, etc..) can have a big effect, but I don't know how to quantify those so I'm just talking about the elements, how much delta P across the element is required for a given flow rate.

I checked some of your gallery pics and I would've looked at more but I'm on a slow cell connection for now. You have a very nice setup, I thought you meant you had both a 6.0 and 7.3 trucks! I agree with your points about the bends and turns in the AIS box compared to your 6.0 installation. However, I disagree with your statement that..."the greater depth of 6.0 filter should result in lower restriction due to greater actual filter media surface area."

My analogy for the AIS element is a lot of soda straws bunched together, where the length of the straws is the height, and the inlet area is the total openings of all the straws. Except for large bugs, etc.. which can completely block the opening to a straw, the dirty air flows through the length of the straws, which allows the dirt to stick to their walls before it reaches the other end. I consider the 37% greater area of the 6.0 as the LxW which decreases restriction, but the 62% increase in H of the 6.0 represents a longer path through which the air has to flow and this increases restriction.

The following description of how the AIS power core works is from page 3 on this link https://www.ford-trucks.com/pdf/05diesel/Selling_AIS.pdf Dirty air travels into fluted channels that are alternately sealed, allowing air to enter through an open flute and forcing it to exit out an adjacent flute. If you follow the air flow arrow in the pic from the inlet (1) through a flute (2), and out the other end (3), you can see that the air never flows "through the surface" the media, but rather along the channels which collect the dirt on their walls, so that the whole inside of the filter fills with dirt. From the picture and description on this page, the air flows through these fluted channels for a total length that's equal to the height of the element. A greater height means more total surface area along all the walls of the flutes, and this provides better dirt collection, however, the air doesn't flow through this greater surface area (which would mean less restriction) but it drags along the surface which means more restriction.

The analysis below assumes laminar flow, described by Poiseuille's Law, where the delta P is proportional to the flow velocity and the length of the channel. For a given total air flow, the 37% larger area of the 6.0 means that the flow velocity in the individual flutes is 37% less than for the 7.3. Now if the two heights were the same, the total pressure drop across the filter would also be 37% less. However, the 62% increased height (length of the flutes) requires a 62% higher pressure drop to maintain the same flow. Combining these two effects gives a 62-37=25% lower delta P (less restriction) for the 7.3 L at the same total flow. However, the 6.0 probably filters something like 100% better. The longer length (62%) and the lower velocity (37%) provides more contact time along the walls of the flutes to collect the dirt.

 

Here's a statment from donaldson about the powercore media:
"It's an axial flow filter -- in one end and out the other," noted Barris. "Typically we see a reduction in the system restriction because of that straight-through flow. Anytime you can get from the intake system inlet area to the turbocharger using as few turns as possible, it will be better for the system in terms of lower restriction."

My education is in Agriculture, not engineering but I believe that the pressure differential required to move a given volume of air through a filter media is going to dependent upon, among other things, the amount of filter surface area. The air does, at some point, flow through this surface in the powercore media. The deeper filter should also allow greater dirt loading with less restriction. The flow bench test for the stock 6.0 system I have see indicate it will flow 770-780 cfm, while the best I have seen for the AIS is in the 750 cfm range.

Well again I'm just a stupid Aggie, not an engineer, but wikipedia tells me that Poiseuille's Law "is the physical law concerning the voluminal laminar stationary flow Φ of incompressible uniform viscous liquid", not air. Again, my my education is in biology not physics and mathmatics, but I think that applying incompressible liquid principles to air might result in flawed calculations.

 

This is a little to the side of your original question but I want to add it to the mix.
I've had my AIS in for a year now and the filterminder hasn't even moved.
The one time it did move was after I went through a hatch cloud of bugs and they pretty near filled the bottom of the element without getting sucked up into the little passages. A little bug removal and all was restored.
Cleaning the radiator was a PITA!
Plus the element has hardly turned color at all.
It may be slightly more restrictive than the 6637, but not enough to be concerned about.
I add that I have a very large, ugly Zoodad mod with no baffling or doorways. It's well hidden behind my billet grill so I never bothered to pretty it up.

 

All said and done, if anyone feels that their AIS set-up is not up to par, for their needs, I am interested in buying one. I will be stay tuned to this thread.

KISS- less filtering material, lower EGT's, More filtering material, higher EGT's, no matter what filter you have on there.

 

You're a little too late, I sold my AIS on E-bay last week.

 

Shucks, Thats the story of my life!

 

Oops, big *duh* there, thanks kwik. Not a good idea.

 

Just went out and took a look at the filter - nothing clogged up in there. I do have the foam "insert" and the hole in the airbox so it can breathe through the fender, but I don't have a vent hole (zoodad?), at least not yet.

By the way I didn't mention that my mpg were about the same, just over 10mpg, close to 11.

I also loosened up the tailpipe clamp to "re-create" what I had before, although I didn't disconnect it. Don't want anything melted. I know I drove (unloaded and towing) for about 1500 miles with this thing loose and nothing seemed affected by it.

If things don't improve on the way home, then next time out I'll try the stock airbox & then 6637 next tow (and deal with the noise) and see if there is a difference. ??

Seems to be some conflicting reports here, some see higher EGTs with the AIS, some don't. Maybe my problem is exacerbated b/c I don't have a 4" exhaust?

 

My search for the truth capabilities with Google have been limited by my snail pace cell connection. I'm at a casino RV park in Tunica MS and they want $10.95 a day for their WiFi which most parks either give for free or 1$ a day. I guess they want me in the casino and not messing on my computer!

I read a review article years ago when they first came out about how the AIS was uniquely different because of the axial flow through the corrugated media with the dirt sticking to the sides and the air never actually flowing through the media like in a conventional filter. That seemed reasonable and stuck in my head as the way the AIS works. The pics in the AIS brochure also misled me because they show the air flow path as going down one flute and then flowing out the end of it and up to the inlet of an adjacent flute and through it and out the other end without flowing through the media. Well I now see that this concept is wrong, I just found the more complete and presumably correct description below.

http://www.donaldson.com/en/about/news/005525.html
This corrugated media is constructed by layering alternating rows of flat sheet and corrugated media.The result is a dense, honeycomb-like structure of filter media. The resulting media pack consists of parallel rows of flutes that are open at only one end. To create a filter from this media pack, the ends of the flutes are sealed at alternating ends with an adhesive bead. This bead of adhesive creates a barrier to air on the upstream side of alternating flutes within the media pack, and a corresponding barrier on the adjacent flute at the downstream end. The result is that when placed in an air stream, the air is allowed to enter half of the flute chambers on the upstream side of the media pack, but blocked from exiting those flute chambers on the downstream side. Because of the permeable nature of filter media, the airflow passes through the media fibers and gets cleaned. Once in the adjacent chamber, it exits on the open downstream end and is directed to the turbine.

So please correct me if I'm wrong about my new interpretation of how this works. The air flows into a flute and axially along it until it encounters a dead end. Pressure builds up in the flute and forces the air to flow through the media along the entire length of the flute so that it enters an adjacent flute, and then along this flute and out the other end.

Based on my new understanding of how height provides additional surface area to reduce restriction as opposed to additional drag of the air along the flute to increase it, I would except to see a larger difference between the two versions than the 3% difference between 775 and 750 cfm. But I'm not trying to open another can of worms, just trying to understand how it works.

 

A flute plugged on the top is open on the bottom and a flute plugged on the bottom is open on the top. Air enters an open bottom flute and is forced to an adjacent flute with an opening on the top. effectively using the entire length of the flute as surface area.
https://www.ford-trucks.com/pdf/05di...elling_AIS.pdf

 

This was my source for using Poiseuille's Law, here it's used for analyzing flow in lungs, so I figured air is air whether breathed in by us or by our engine!....

"When flow is low velocity and through narrow tubes, it tends to be more orderly and streamlined and to flow in a straight line. This type of flow is called laminar flow. Unlike turbulent flow, laminar flow is directly proportional to the driving pressure, such that to double the flow rate, one need only double the driving pressure. Driving pressure during turbulent flow is in fact proportional to the square of the flow rate such that to double the flow rate one must quadruple the driving pressure."
http://oac.med.jhmi.edu/res_phys/Encyclopedia/AirFlow/AirFlow.HTML

Speaking of breathing, I'm now trying to calculate just how many cfm our engine breathes in versus rpm and boost. Check this out and let me know what you think.

As a plain air pump, it breathes in its displacement of 444 in^3 for every 2 revolutions of the crankshaft. This gives...cfm=(0.1285)*rpm. As a round # example, 300 cfm=2,335 rpm. I think an engine can suck about a 30" H2O (1 psi) vacuum during an intake stroke, and atmospheric is about 15 psi, which gives a driving delta P=14 psi to maintain this 300 cfm flow. Now assume 20 psi of boost from the turbo, this gives an additional 5 psi of driving delta P, or about a 19/14= 35.7% increase in flow to 407 cfm, if flow is laminar and proportional to delta P.

The above method for 3,000 rpm gives 386 cfm and with 25 psi of boost gives 662 cfm, and your data point for the AIS was 750 cfm, so I'm thinking that these simple minded calculations might be pretty close for predicting air flow into the engine.

If the filter hits the maximum restriction of 30" H2O (1 psi) before changing it, this reduces the flows from 407 to 386 at 20 psi boost, and from 662 to 634 at 25 psi boost. The 6.0 revs to even higher rpm and has higher boost, so it clearly benefits from a filter with higher flow rate capability.

BTW, don't take the above analysis to the bank, I'm a EE so this is far removed from my field, but it sure is fun trying to figure out how other stuff works!

 

So hopefully this means that you're agreeing that my new understanding of the AIS that I posted above is correct?

Please let me know if I still don't have it right, and check out my new post on Air Flow Analysis, and let me know what you think of it.