Outstanding work Jason. It was methodical and scientific. I tried to rep you but I'm in jail. I seem to be in rep jail for a lot of people.

 

Thank you Noob. It wasn’t as scientific as I would have liked though. Would love to to go back and do the testing with the proper gauge and with more data. But I really don’t want to put my PMR’s through that again.

Would also like to tow again with the sleeve for comparison data but that’s out until spring. Not sure when my uncle will want his gauge back either... luckily he hasn’t needed it since I borrowed in the summer.

There seems to be a significant difference in vacuum/restriction between sudden WOT demand for air and a constant 20psi.

All in all it seems Tugly was right all along. Anything beyond about 25psi and the AIS struggles. But it’s oh so quiet.

———
Well before hitting reply I went on a gauge search, you know just because. It seems a properly accurate gauge is more difficult to locate than I thought. Maybe somewhere like Grainger or such to find instrumentation type would be a better place to look but I was just using Google.

Anyhow, this is probably the closest I found to the proper gauge. Our testing at the FM location runs about 1inHg = ~0.5psi. So still not using much of the gauge but would be better than what I used.




Then I ran across this when searching for “filter restriction gauge”. I have no idea what it is for (probably fluid measurement) but wow it stays “green” all the way to 8inHg. This sent me on a search to get an idea of what a “normal” allowable filter restriction would be.


This is a FM found at NAPA which appears to be similar to the one on our trucks. I have no idea what the actual application is. I moved on before trying to look that up. The gauge readings seem to match what I would expect our stock FM to pull in at. Note: all of the below read inWC as opposed to our inHg testing.


I felt like this was interesting because it was a Donaldson FM. It is showing “red” at 25inWC = 1.8inHg. We topped out the AIS at ~0.85 when sleeved.


The next 2 are universal and both show going red at 20inWC = 1.5inHg



And finally here is one from K&N. They like to let more air (and dirt, sorry not a fan) in so their gauge goes red at 10inWC = 0.7inHg. This is actually similar to what I feel our factory FM would do.



What does all this tell us? I don’t know but did find it interesting.

 

Thank you
that sort of answered the burning question ive been having.

 

Which part?

I also found some interesting information on filter flow rates but getting trusted info from each filter was very difficult. I may share this in the future. My goal was to get flow rates from the same manufacturer of each filter so reduce the spec variance. Not so easy to find believe it or not.
Basically from what I found the standard AIS filter has a better flow rate than the typical 6637. That goes completely against our testing results, but I was also using the riffraff Donaldson blue.

 

Mainly what is considered “restricted” with a factory filter for a 7.3

 

I will be checking the actual FM (AIS and regular) with the vacuum gauge once the testing apparatus is off the truck.
I tried to do this at the beginning of this saga but my gauge wasn’t working so well. My uncle's gauge should give me more viewable results.

 

I cant wait to hear these results!

thanks!

I guess i should add
the s&b on my 2001 pegs the factory filter minder with stock turbo, 65hp dd php tune and wastegate plugged

 

WHAT?!?! For real?
The AIS with stock FM doesn’t peg in a 65 tune... well at least not from what I remember. I’m gonna have to test that out now too because my memory is fuzzy. Or you can do it on your other truck to compare.

 

In my 2003 with plugged gate and same 65 dd tune and stock ais it puts the filter minder right to the edge of the green. Near “pegged”

i noticed this on my 2001 and cleaned the filter thinking that was the issue awhile back. Back to the same after cleaning and reoiking following s&b’s instructions closely using the correct amt of oil(pain in my ***)

 

This is quite interesting. From the looks of it your AIS is actually showing less restriction than the S&B. Goes against all logic.

Would you care to swap FM’s to confirm it’s not just a difference in them?


Well I was going to do more digging before opening this can of worms but I dropped part of the info in another thread so here we go. Finding flow rates for the filters is challenging. My goal is to find specified rates from the same manufacturer so the testing conditions would be constant (in theory anyway). I could not find anything on the Baldwin filters. The Riffraff blue Donaldson shows a flow rate but it does not give any details for how they test so I can’t even say it would be apples to oranges to listed flow rates on other sites. In reality the testing methods and claimed rates could differ greatly.

What I did find was 3 filters with flow rates on WIX’s site. No details of the test method but at least can partially assume they would test all their air filters under the same criteria.

Here’s the interesting part.
1- AIS winner at 775 cfm
2- Stock at 640 cfm
3- 6637 last at 425 cfm

This goes against the testing results so I feel there is more to the story that is not understood.

Points to note:
a) None of my testing is with WIX products.
b) My vacuum gauge testing was with the RiffRaff blue Donaldson “6637”
c) My AIS has the filter provided with the kit, Donaldson I believe.
d) 6637 FM testing (FM in end of filter) was with an old Donaldson filter purchased from TYMAR, which claims to be better than a normal 6637. FM testing showed definite results that this 6637 did not have as much restriction as the AIS(no sleeve).



WIX AIS 775 cfm


WIX Stock 640 cfm


WIX “6637” 425 cfm

 

I will swap the minders and see what comes of it!

i wonder if all these are being tested for flow at same vacuum?

 

Thanks for the assist!

Yes, that’s what I wonder as well and exactly the reason I was attempting to get the info from the same manufacturer. Or get results including the test vacuum. I’m sure there’s a lot more to it than that but I couldn’t find any specifics so

You would think WIX would perform all their testing for the filter specs under the same conditions but I would guess that’s incorrect.
On the other hand, Charlie from KC said he has seen intake boots sucked flat with 6637 filters. Maybe the flow rates for different brand filters are drastically different.

Of course one thing to consider in this is the restriction from the box. I would image the listed flow rates are for the filter itself outside of any box. As we have seen in our testing the AIS box poses a restriction as well.

 

The filter you are showing is for a 6.0L application, that not only has a completely different air box, but has a different flow path, directly into filter channels from snorkel.

The Wix filter for the 7.3L application is 49090. The cfm rating is the same, at 775, which suggests to me that the Wix testing methodology does not include the air box.




When I tested air filters years ago, I used a Super Flow calibrated flow bench, with the restriction set to 25" H2O, and I included the entire air box in the test. This meant strapping the whole airbox to the flow bench. I lost an entire day of testing after discovering that I was inconsistent in how the inlet mouth of various designs of air boxes would end up at different clock orientations relative to the wall that the flow bench was adjacent to.

Just that little bit of difference was measurable by the flow bench, and thus I had a pile of unusable data from the previous days tests, which I had to do all over again, this time being very specific about the mouth of the inlet snorkel facing an exact degree and distance away from the wall.

One of the filters I tested is that Wix 3" pleat flat panel (46728). I don't have the results handy (on a hard drive that I haven't accessed in 15 years), and the study results are no longer available online, but when I tested it, I strapped the entire Ford OEM Air Box to the flow bench... box, base, lid, inlet snorkel, curved boot, the whole kit and caboodle. Ran it at 25" H2O. I don't recall the CFM result specifically, but 578 cfm seems to keep coming back to mind. Don't quote me on that, as I tested Motorcraft brand and production filters at the same time. To my mind, 640 cfm is in the ball park, or at least the stadium, with 578 cfm, given the influencing factors unknown, and thus unaccounted for, like did they test at 10" H2O? 15" H2O? Did they use the full factory air box or an adjustable test fixture for flat panels with a Pitot tube? etc.

 

Well shoot, how did I miss that? I told you mining for the data wasn’t as easy as I’d thought. And I typically do it on my phone so that doesn’t help much. There’s a couple excuses if you’re buying them.

Seriously thanks for clearing that up about it being the wrong filter. I’m glad at least the cfm was the same.

My thoughts were also that they tested these filters without a box for the flow specs. Of course that was just speculation on my part so it’s good to hear someone agree with this thought.

I would also wonder if they test them at a vacuum that will yield BIG flow ratings. It’s all about the marketing right? I assume this would be a higher vacuum to make bigger flow numbers.

The one thing that is still nagging is the WIX flow spec of the 6637 which is by far the lowest of the bunch. This does not seem to match the real world testing results. I can’t image the flat panel stock filter would really flow more than the huge 6637, even without a box. Or possibly the WIX version is just that much different than the Donaldson?

 

Took some time this evening to compile a few video clips of the testing runs. Unfortunately it took such a random course that back to back apples to apples comparisons aren't available for each setup.
For example, I have never had the 6637 paired with the 363 turbo. I also wanted to show a 65hp comparison between the 2 turbos, but didn't have runs that are equivalent. The 363/68 responds better on the milder tune. The 364.5/73 liked to be in a hotter tune.

You can see from the 1st to 2nd clips that the 6637 does allow more max boost than the AIS. The thing is, this really only happened when running a HOT tune and WOT. This is not the way I normally drive so it's not much of an issue to me. Is there some performance left on the table with the AIS? I think so. But the AIS is so clean looking and SUPER quiet. Those 2 reasons have made me keep the AIS for now. So far I like the setup.

Edit to add: Also notice the Fender Sleeve mod did improve both boost level and lowered restriction. This backs up the historical wisdom of it giving the AIS a little more reach in the performance department.