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See now this is where our theories differ. I feel like the flat opening in the intake tube would have the “fancy word” vacuum effect when air is going past it. Much like blowing across a pop (WV for soda) bottle. I also feel the reason Ford (or international) added the hood was to decrease this “fancy word” effect. I could most certainly be wrong as these are all just theories. But since we disagree you now prompt me to go digging for research....or do a special test with the CSD intake.... I’m not gonna lie, I’m kinda in the mood for this testing to finish up as I keep going out and doing 140 tune WOT runs and that’s not really my thing. Lol
As for the green tube, yes Sous has also mentioned it earlier and it would work well as the vacuum tube would probably hook up nicely there. But alas I no longer have that portion of the intake since I’m running the T4 setup. This would be a nice easy spot for someone else to connect though if they wanted to try and duplicate my testing.
SSJ thanks for the comments and intellectual bantering. When getting different points of view it helps us see things that we would otherwise miss.
Side note: “fancy word” = that’s what I get for not quoting SSJ and being too lazy to google the term during this response.
My theory is the hood thingy increases the pressure drop MORE than the open hole would by itself.
My ‘problem’ is the volume of air should be similar at a given boost number. Perhaps a greater restriction at the filter increases the Bernouli/Venturi Effect??
Its Times like this that make me wish I was smarter... I used to call a retired physics professor when I had a question like this. If only I could remember everything he tried to teach me...
My theory is the hood thingy increases the pressure drop MORE than the open hole would by itself.
My ‘problem’ is the volume of air should be similar at a given boost number. Perhaps a greater restriction at the filter increases the Bernouli/Venturi Effect??
Its Times like this that make me wish I was smarter... I used to call a retired physics professor when I had a question like this. If only I could remember everything he tried to teach me...
Maybe it’s the Venturi Effect I’m thinking of. Like you said it’s been a long time since physics class.
My thought on the difference at the CCV is that the numbers stack.
Venturi Effect + overall filter restriction = total vacuum
so let’s just throw fake numbers in there for the AIS CCV test to help visualize.
At low boost (low volume) 0 + 0 = 0
20psi: 0 + 0.75 = 0.75
25psi: 0.1 + 0.9 = 1.0
32.5psi: 1.0 + 1.0 = 2.
Something you mentioned earlier made me think maybe I messed up my explanation of the CCV vs FM position numbers. The only testing I have done at the FM position is with the AIS. I do not have any data on the 6637 in a condition without airflow across the vacuum gauge location.
I think your hood theory may be correct if the hood was turned around. But in my mind the hood actually catches a bit of air as it passes by and would cause it to have less of the Venturi effect. Again just us bouncing theories back and forth. I have stuff to do now but hopefully can do some internet physics learning later to see if we can get a better educated guess at what’s going on here.
Well there’s been a new development in the data collection. It appears some dummy forgot to tighten one of the boot clamps down during the gauge location swap. So it’s possible the lower vacuum readings were due to leakage around the boot. Kinda doubtful but still a possibility.
Sooo the gauge remains in the FM port location for another check.
Red arrow is where some stupid guy didn’t do his job.
Blue arrow is the gauge location.
These were at the CCV port location. Current testing is to confirm if the airflow is effecting the results. Then we also need to get some AIS towing data. I’m planning on getting this data at the CCV port for a few reasons.
1-it’s easier to hook up there. I do not have a FM hole in my new 6637. Also not sure the vacuum line would reach the hole I added to the old 6637.
2-I already have 6637 towing data at the CCV.
3-I’m not sure how many more times I’ll be towing this season.
4-I’m ready to wrap this thing up. Lol
Ah who am I kidding? What will probably happen is I’ll tow to the track with AIS in one configuration, swap it around while there, and tow back with AIS and gauge in the other location.
Y2K, my ultimate plan is to go back and edit the first post with results after the data collection. Probably throw it in a simple spreadsheet as well. Then future readers won’t need to dig through pages of my rambling to find the answer.
Y2K, my ultimate plan is to go back and edit the first post with results after the data collection. Probably throw it in a simple spreadsheet as well. Then future readers won’t need to dig through pages of my rambling to find the answer.
Spreadsheet sounds good. I did indeed read the entire thread from start to end, and it was a little challenging as a reader to condense comparisons from the "rambling", but all the same completely understandable as journal entries made contemporaneously as you excitedly discovered them.
The impression that lingers from your narrative thus far is that under the engine loads and with the tunes that you expect to operate in, there is no appreciable difference in measured restriction between the AIS and the 6637.
You further found or felt a slight performance difference between the AIS and the 6637 that you felt was counter-intuitive, in that the slightly more restrictive AIS felt more responsive, despite slightly lower boost pressures at the maximums measured with the 140 tune, and you questioned why.
I would offer Air Density is why, where the air pulled in from outside of the vehicle is slightly lower in temperature and commensurately denser in oxygen molecules that supply more energy when burned, than the slightly warmer engine compartment air that the 6637 draws in, where that warmer air is expanded, and less oxygen dense.
The baffle that you created extending the snorkle remains of the stock battery/airbox ensemble with your 6637 installation was interesting and appreciated. You mentioned that this extension might "block" heat from the engine and exhaust manifold, but it seems to me that unless the air filter is entirely sealed off from the engine compartment, the hot air under the hood will continue to undermine the density of air that is ingested by the open 6637 filter.
From a performance and efficiency perspective, to get the most power out of the least amount of fuel expended and heat wasted, I think we all agree that density (higher oxygen content) is more effective than pressure (boost) when it comes to intake air.
A gauge is calibrated to be the most accurate in the middle of its' range of measure. I did wish you had a gauge that had a smaller range of measurement, if only to make the reading differences easier to discern. I'll bet that you wish the same, as you squint to try and interpret a needle moving less than its' own shadow on the dial. However, what you have done with what you have is so much more than what most have done or are willing or able to do, that I had to join the chorus of appreciation and admiration for what you are bringing to this community with your testing.
The last time I tested air filters and air box ensembles for the 7.3L, (many years ago) I had the benefit of using a $30,000 flow bench, and a budget to go out and buy every aftermarket air filter and airbox I could find, at whatever retail price whoever had them wanted, in order to complete the testing within the 3 day period of time I had access to the flow bench for. And even under near laboratory conditions, setting the flow bench to a consistent 25" water column restriction for every configuration tested (to simulate ***** to the walls air demand), I discovered that a MEASURABLE difference in flow could be attributed to the degree in which the air box ensemble was clocked when mounted to the flow bench machine. I had to throw out a day of data and retest everything all over again, this time positioning each airbox assembly at the exact same clock rotation on the machine itself, due to the air "o" dynamics of the wall the flow bench was adjacent to. This is where more sensitive instruments provide more accurate data only if the person doing the testing is mindful and observant of potential contributing factors. So I enjoyed reading how all the factors you are thinking of in your thread journal.
My “Thread journal”, a very good description of the incoherent ramblings of a nut job. But seriously that is exactly what this has been. Me sorting out my thoughts and findings as we journey along with the help of challenges to theories from engaged members.
You summed it up pretty well actually. Maybe you should write the update to the opening post!
As you said, I do wish I had access to a different gauge with a range better suited to our testing. But not so much that I’m willing to go purchase one just for the task. At the end of the day this is kind of just a fun experiment. Making due with what’s on hand (or on hand at my uncle’s garage) lol. I was actually going to purchase this same gauge for the testing until I realized he had one. Of course at the time I had no idea of the actual numbers we would be seeing.
I would also love to see this test performed on a flow bench with people (maybe you) who are knowledgeable on air flow.
I believe to perform the test correctly we would need to have a different gauge and place it in the no air flow location for both filters. Honestly something I’m not willing to pursue at this point.
Bottom line is I will try the AIS towing and if it doesn’t show any signs of issues I will likely keep running it. It’s just that much quieter and looks nice. If/when I finally put the CCV back to the intake then I will need to re-evaluate for any oil consumption concern as SSJ mentioned.
The FM location test has been ran again with the tightened boot. No change to the results. That is with the exception of a small increase in boost likely due to a lower outside temp of 71*. This time the AIS seemed to flatten out at 33psi of boost. The 6637 was around the 34 mark. So we are seeing a loss of 1-1.5psi when running the AIS.
Here’s some snapshots of the video.
PHP 140hp, AIS with gauge in FM location, 71* ~12:00
The air "available" to ingest by the AIS (to reduce restriction) can potentially be improved by doing the SECRET Zoodad that Ford did to the 2005-2007 header panels. (A bit different from Zoodad's zoodad).
The air "density" under the hood ingested by a 6637 open element can potentially be improved by doing some type of Dam. Double Dam. modification, not for the just the efficiency reasons discussed in that thread, but for reducing under hood temps by increasing the negative pressure under the truck, which will support faster air exchange under hood, as hot air may more readily escape through the transmission tunnel into a low pressure zone rather than a high pressure zone.
So even with open air filter elements under the hood (which I personally would discourage for reasons beyond the scope of this thread), there is an opportunity to potentially reduce under hood temperatures by better managing the air flow under the truck... which is exactly what OEMs do, and is usually the first thing that truck enthusiasts UNdo.
Up in the 17 forum, I have combined some 6 simultaneous threads from members who can't wait to pull off the lower air dam that Ford installs on higher 4WD trucks, and ditch it for the shorter cut air dam Ford mounts to the 2WD or off road package Tremor trucks. And they do this only for looks. So they throw away some of the engineering that they just paid $80,000.00 for. I don't get it, but I help them by supplying the part numbers for the "look" they want.
The air "available" to ingest by the AIS (to reduce restriction) can potentially be improved by doing the SECRET Zoodad that Ford did to the 2005-2007 header panels. (A bit different from Zoodad's zoodad).
Ah but your forget sir. I have the secret zoodad mod and put the write up in your thread to prove it.
I highly recommend the secret zoodad but wouldn’t say the same for the “normal” version.
A good point to bring up though because it is possible my truck with the secret Z may get a little extra air to the AIS compared to one without it.
Air flow under the truck? Now you are kicking it up a notch! Not a bad thought and I can see the benefits. Your double dam was interesting and I especially liked the fella’s 2010 version too. Might be something I look into in the future. Doubt there will be any testing involved though.
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But seriously that is exactly what this has been. Me sorting out my thoughts and findings as we journey along with the help of challenges to theories from engaged members. 
