If you haven't already, check this link http://www.duramax-diesel.com/spicer/index.htm for info on flow tests of filters. See what it says about the Baldwin PA4134, is this the same as the 6637 that you're using? Look at those restriction #'s, I don't see how you can flow enough CFM to produce 20 psi boost and not generate more than a 2" vacuum restriction. I'm sure you've checked all your connections to make sure you're not sucking unfiltered air from downstream of where your gauge fitting is located.


A 10' hose should be no problem, my 1/4" dia hose is about that long. This is the easiest test I can think of, take a clean white cotton tee shirt, wrap it around the outside of the 6637, and do a quick test drive. That should definitely provide enough restriction to pin your gauge. If you still see a low reading, then it's really "Houston we've got a problem" time!

 

I think I am going to, pardon me, duct tape all of my intake fittings temporarily before I move anything. That is the only way I can be certain before moving to something else. Pulling the boat out for this is not that simple, so I will bump up the DP and go attack a hill or isolated stretch of road and see what happens. I will not say unequivocally that I do not have an intake leak, but I doubt it. I'm going to find out though.

EDIT, then I may try the filter wrap restriction idea if there is no change.

 

Tenn, I know you already thought of this one, You did use thick wall tubing, to ensure its not sucking the walls shut..

It takes a little while to get feedback, but an Oil analysis will tell you if you have a intake leak(on the suction side).

 

I'm back sooner than I expected. Had an emergency over at my in-laws, so had to crank up the truck. Since it was so close, I let the truck warm up after I got back.

Got a towel and wrapped it around the filter. Hit the go pedal and was able to hit 5" on the gauge with ease, with no load or boost, sitting there in park. Seems to me the intake is in order and the filter is working real well. No need to test drive that as I know I could peg that without leaving the driveway.

So 6637 gets a big thumbs up from me so far. I guess the next step is to move the tap site, and test again. I'll let everyone know when I get around to that.

 

6637 Rocks! If I can find 5lbs of boost with it over three different filters I think it's a keeper. Oh and no measurable difference with no filter.

 

The results so far make my all that more confident in the SOTP feeling I got after first installing it. Tenn, I don't think you have anything wrong with your measurements. I'm now pretty much convinced that I'll be keeping it under my hood. If I can, I may just have to lay my hands on a Magnehelic and see what I see...

 

Guys- Im thinking about making a stainless box to enclose my 6637 and running a ram air tube to front of truck directly. Do you think I need to run 4" round or equivilant or will a smaller pipe work? Anyone with an AIS setup can you measure how big opening is on inlet side and post dimensions ? Thanks, Bill

 

This speaks volumes for me, and I have now kinda tested it. I will continue the testing.

 

I had to go back and address this post because it seemed so wrong at the time and nobody else answered it. I think this particular filter must have gotten wet or something because it is simply so huge. I know Gene has posted restriction vs flow #s and I didn't like what he posted. So far, my analysis agrees with Mech, this filter easily outflows what is needed in our 7.3.

 

Check the last few posts on this thread... https://www.ford-trucks.com/forums/645913-intake-2.html#post5069254 and see if you can come up with an explanation for the differences in restriction seen during bench testing and what you're seeing as installed on your truck. Read the link provided there concerning the tradeoff between restriction and the ability to actually filter out the dirt and dust from entering your engine. The data in the link shows that it defies the laws of physics to get both low restriction AND good filtration. Below is a quote from the link...

"Restriction to Flow: The Restriction to Flow curves graphically show how each “clean” filter responded to a steadily increasing flow of air up to 350 CFM. The Flow Restriction response curves for each filter have the same basic shape. However, note how the AC Delco Filter, which passed the smallest amount of dirt and had the highest dirt capacity and efficiency, also had the highest relative restriction to flow. The less efficient filters correspondingly had less restriction to flow. This illustrates the apparent trade-offs between optimizing a filter for dirt capturing ability and maximum airflow."

 

Uhhmmm, Gene, what is the point in testing if you think you have the answer and dismiss the results when they do not agree with expectations? I am not done with this by any means. I am going to tape up all of my connections to the turbo and suck up the cleanup from that just to confirm my #s. I also want to make absolutely sure I do not have an intake leak. I will even move the tap/input source.

Let me continue the testing. It almost seems like you have a 6637 chip on your shoulder, and that does not allow for objective testing. Perhaps the sheer filtering volume of the 6637 explains it's ability to flow. Look at the size of the opening in the turbo inlet vs the 6637 filtering area. I bet a 55gallon drum sized 6637 filter would show zero flow restriction through there.

So your AIS is no doubt a great filter what with fresh air pickup. Of course Ford said it was better, what isn't better than that stock panel leaker?

Was not the conclusion of the Dmax test that the AC delco stock paper filter performed best? Also, on the graph I did not see anything above 2" water on the leading filters. Am I looking at the wrong graph or post?

At any rate, you have posted your flow rate predictions from some bench test from somewhere. If you were satisfied with that, then why am I doing the testing I am doing? Well, because real world numbers are what we are concerned with. When I see they do not match the expected #, I look for a reason and retest? They are what they are and will not be "dismissed".

So please do not ask me to explain how something seems to defy the laws of physics. I am going to make measurements, and post the results. If you do not like them, I cannot help you, except to say I will be happy to ship the gauge to whomever you like when I am done testing everything I want to test.

In the meantime, unless I find an intake leak, the 6637 is performing very well.

 

I'm not dismissing your results, I'm just trying to reconcile them with the laws of physics based on my 40+ years as a working (getting my hands dirty) engineer, and in that time, I've definitely learned what a rat smells like, by that I mean something that doesn't seem to be working correctly!

I think I might've figured out why your readings are lower than expected. I think you have to move the location where your fitting is from the end cap to between the neck of the filter element and the turbo inlet, which is the directions for the DONALDSON B085011, which as far as I can tell is the cross reference for your 6637. Your current location is well upstream from where all the sucking is happening!

The way I see it, a vacuum first develops at the turbo inlet, then moves to the neck of the filter, and this starts sucking air from the portion of the open element filter that's nearest the source of the vacuum. For a large enough CFM demand, the vacuum at the filter neck increases, and gradually progresses up the inside of the open element toward the end cap as required to pull in more air to meet the demand.

The reason my towel wrap experiment gave a reading is that the wrap forced the vacuum up to where the fitting is so it could read the restriction. With the fitting between the filter neck and the turbo inlet (like mine is) you'll be reading the restriction due to all the air flowing through the entire filter element, whereas now you're only reading the restriction due to the little bit of air that's flowing through the end portion of the element.

Yes, no need to mention that I'm the one who suggested where to put the fitting in the first place, and that's where many put a restriction gauge, but with an open element filter, and with the directions on the DONALDSON site, it's now clear that's the wrong place to have it.

First, I found the following on the wix.com site. Note the CFM rating is only 425 CFM, but the wix site didn't have any restriction data.

Part Number:46637
UPC Number:765809466371
Principal Application:Air Filter Assembly for Various Equipment.
All Applications
Style:Air Filter
Service:Air
Media:Paper
Height:12.380
Outer Diameter:8.500
Inner Diameter Top:Closed
Inner Diameter Bottom:4.000
Ends:Metal
CFM:425

Then I found this cross reference number for supposedly a DONALDSON B085011 equivalent to the WIX 46637, which are both also the same as a Baldwin PA2818.

PA2818 WIX 46637
PA2818 DONALDSON B085011

Here's the DONALDSON site, and it gives restriction vs CFM data, which to me, implies that at a 20+ psi boost you should be measuring 6" to 8" H20 if you relocate the fitting to where DONALDSON suggests on the last page of the link, they also have a pic there, but I couldn't copy it.

http://www.donaldson.com/en/catalogs/engine/033621.pdf

ECB Initial Airflow Restriction
CFM @ "H20 Air Cleaner
..4".... 6".... 8"... Model
280.. 400.. 470.. B085011

Service Indicator Location: For proper restriction readings, a restriction fitting tap must be located between the engine intake and DuraLite outlet neck. The tap should be located in a straight section of the intake pipe at least one pipe diameter away from the manifold or any bends, elbows or reducers.

Now, I don't care who uses what filter on their truck. However, when new users sign on and ask, I try and make sure they get the other side of the story so that at least they can make an informed decision. In your case, I'm only interested in getting a lot of CFM vs boost vs RPM data on a 99.5+ truck. I'll offer to buy you the B085011 equivalent to your 6637 (what brand is your current one?) because the B085011 seems to have measured CFM vs IN H20 restriction data to calibrate the CFM measurements. Check out the site and place an order for the genuine article, and let me know the cost, and I'll send another check, all in the name of good science!

 

In this case, the "because it is simply so huge" factor is working in favor of a potential collapse! I don't want to be accused of bashing the 6637 on your thread, I've been doing a pretty good job of that here... https://www.ford-trucks.com/forums/645913-intake-2.html#post5069254 As I've already stated, I'm primarily interested in the CFM going into your late model engine, of course you've got to measure that using the calibrated restriction data for your filter.

Back to the issue of filters collapsing, the dimensions of the 6637 filter give an outer shell area of 330.6 in2. According to the DONALDSON site a clean new filter at a flow rate of 470 CFM gives a restriction of 8" H20=0.289 psi, and this gives a (0.289*330.6)=95.55 lb of total compression loading on the outer shell. For a dirty filter at the end of its service life the restriction might increase by a factor of 2.5 compared to a new filter, and this 20" H20 restriction will cause a 238.9 lb loading. With that kind of compression loading, it's not hard for me to see the potential for disaster at a peak flow of 500 CFM or more that you might incur during a burst of WOT operation! Here's a good link to that subject, and a bunch of other good stuff as well.

Heavy-Duty Diesel Engine Air Filter Collapse
http://www.filtercouncil.org/techdata/tsbs/06-2.htm

A common cause of filter collapse is not paying attention to the service point recommended by the engine manufacturer. Diesel engines typically have an intake element service point of 20-30" H2O.

It is also important to inspect all filters before installation. Dented liners or end caps may result in a loss of structural integrity and filter collapse. Damage may be present but not very visible.

Operating conditions should be considered as well. For example, high levels of soot (generally from diesel engine exhaust) can plug an air filter rapidly. This may shorten the life of a filter dramatically, and if a restriction indicating device isn't monitored closely, can result in extremely high pressure drop across the filter that may cause it to collapse. Water ingestion can be a concern, too, one possibility of excessive water ingestion often not accounted for is the introduction of high levels of moisture during washing of the vehicle.

 

I'm having a problem visualizing why the vacuum inside the filter will be less at the end compared with at the neck. Also, if you put the pickup tube in the intake flow, you're going to get some funny numbers because of the air flying past it, aren't you? I seem to remember a post about the stock filter-minder giving false indications when placed directly in the flow. Will this not have the same problem?

Joe

 

Well I am back. It is official, there is little to no vacuum to be had at the far end of the 6637 filter because that's just the way it is from my measurements. It seemed obvious to me there would be little there but I didn't imagine that little. I want to thank Gene for talking me into mounting it there despite my doubts and the fact that he has already accepted credit for that move. That has been TESTED.

All filter minders are placed downstream of the filter in the intake tract for an obvious reason now, not just because that is what is called for on the Donaldson Fleetrite site.

I have moved the source of my tap back to the connection at the 6637 and the intake. I hate that PVC but it was a better option than drilling my pipe that I normally run there. I made a quick run down the street to a small hill. With no load, getting on it only slightly in the 80e setting I observed, roughly, at 15psi and 2.8k rpms, I was getting about 9" of water. Alas, now it is time to do some serious testing.

I will try to get a good set of #s in the next day or so with a load and a decent hill. Now I am once again interested. After that, I will move the tap down by the reducer tube near the turbo. Ought to get interesting then.


BTW, before anyone asks, that fuel line going into the old intake tract is my dead end bleed hose that I also hook a gauge to when I want to check my fuel pressure. Not much to see, just a valve at the end connected to a T-fitting that is plugged unless I hook up a gauge.