TheDieselStop.Com Forums: A I S SUCKS

FWIW, when Gale Banks and I first started mounting complete stock Superduty as well as complete aftermarket Superduty airbox assemblies, in their entirety, snorkel and all, to his $25,000 flow bench that was installed near a partition wall separating two rooms in the engineering building, neither of us really paid attention to the relative orientation of the snorkel in the vast, high ceiling space above the flow bench machine.

We were testing away for the better part of our first day on the project, when an anomaly appeared. While attempting to verify some results by dupicating tests with the exact same set-ups, to establish repeatability of the findings, lo and behold, some of the results were showing up different. Not by a lot, but by enough to notice.

We considered the temperature of the room, the number of persons present, and the associated activities of those personnel. We barred anyone from moving within 15 feet of the machine whilst a test was taking place. Some one even considered changes in barometric pressure, or the relative humidity, yet none were noted, as we were entirely indoors, in the center of the building, on an even keeled, weatherless Southern California spring day.

Something wasn't right.

As the assembly and dissassembly of airboxes on the flow bench and their commensurate testing continued, I described to Gale the popular Zoodad mod (drilling 3" to 4" holes into the radiator support baffle in front of the snorkel inlet). While describing such, I placed my hand a few inches from the stock airbox snorkel inlet then mounted on the flowbench, and a very audible sound change in the machine, as well as a substantial numerical and graphical data change reflected by the $5,000 flow and restriction evaluation software package flickering on the computer screen, immediately became apparent.

My truck at that time was parked inside the Banks prototyping shop, right next to where the little red 222 mph Cummins Durango was then under construction, and Gale obligingly walked over and looked under my hood several times, as ideas came up and discussions ensued, including discussions regarding this baffle.

At this point I should admit that I wasn't speaking favorably for the Zoodad hole idea. (Nothing at all against Zoodad the man! I just didn't favor this particular Zoodad idea, never did, and still don't.) I was busy pointing out all of the risks with the Zoodad, many that have since borne out to be true... one example as reported above, and many others in other threads... such as wind/draft driven rain and tire generated water mist (by other vehicles on the highway) getting sucked directly into the intake, saturating the filter media, and in the process of freezing, collecting and attaching more water droplets to form an ice dam in the air filter, blocking all or nearly all passage of air. In the summer, the Zoodad hole could became a 60 mph shopvac inlet port hole, clearing the air above the road of many of the bugs that might otherwise end up splattered on the windscreen, thus prematurely loading the filter.

By the way, I once found an entire mocking bird stuck behind my grill. I have a 35mm photo to prove it.

But Gale Banks pointed out some other flaws in the homemade hole... the hard cornered, square cut edge of a hand drilled and filed smooth hole will actually allow less passage of air than the overall size of the hole would suggest, due to the disturbance of laminar air flow that would not be present if the hole's edges were fluted, with a radiused inlet around the circumference, like a trumpet horn, a "Super Scoop," or a "ported and polished" cast manifold opening. It is difficult to predict what effect that turbulence would have on the pattern of air flow in the space between the hand cut hole and the snorkel inlet. But do notice that even the perimeter of the stock snorkle inlet that opens into that space is fluted with a radiused edge.

In fact, the edges of most any designed flow port, be the medium air, water, sound, or what-have-you, looks like a megaphone speaker, or a supercharger inlet, or a funnel, where flow is gradually guided along a smooth, rounded, unfettered edge to minimize restrictions to laminar flow from turbulance. Where turbulance becomes an issue with the Zoodad is not so much the idea that "yeah, sure, the Zoodad hole isn't constructed optimally, but so what? at least the hole is there, and some hole is better than no hole at all...", no, on the contrary, it could be justifiably argued that some hole could potentially be WORSE than no hole at all due to the induced turbulance causing air resonance waves to be created... unpredicatble pressure waves that interferes with the otherwise designed non-turbulant suction of air from the stock engineered "quiet" inlet zone.

So the Zoodad hole is thus attacked on two fronts, one front based on real world practical risks, and the other front based on it's theoretical efficacy.

But before any Zoodad swearby's angrily hit the reply button to fire off a response on how it's worked for them for three years running, bear with me a while longer as Gale and I return back to that flow bench, with my hand hovering in the air above the inlet scoop, noting the instantly registered performance drop that responds in lock step with the distance of my hand from the inlet. Your vindication may be forthcoming, and it might just be a crow stuck in my inlet next time, rather than a mocking bird.

You see, it finally dawned on us.

It was the partition wall behind where the flow bench was installed!

This wall stood vertically over two feet away from the actual snorkel inlet, an inlet which was always pointed UPWARD, not outward, not horizontally, and certainly not directly towards the wall. Yet, on the costly equipment as sensitive as what we were using, this wall turned out to be the root cause of the registered differences measured between efforts to repeat results of our tests, because we were not inititially consistent with rotation angle of each of the airbox configurations while mounting them on the machine. Inlet Up is Inlet Up, right? Not in this case.

Gale told me to throw my pad of paper away.

What? I had just spent the better part of that day painstakingly writing, by hand, each measurement the flowbench computer recorded. It's not that Gale Banks doesn't have a laser printer. It's just that I wanted to make sure the data didn't get "altered" or adjusted at the time of printing. I recorded what I saw contemporaneously, with my own two eyes. Shame on me for not trusting our generous and very patient host (Gale), who never gave any reason to doubt his earnestness, but afterall, I thought, he is an aftermarket vendor, and we were testing competitive aftermarket vendors, and therefore to be fair to those vendors, (and to Ford), I wanted my very own, directly obtained data.

Gale had to repeat himself, as he saw me standing there sheepishly holding on to my vastly scribbled yellow legal tablet... for dear life.

"Throw it out," he commanded. "We are starting all over."

"But noooo," I whimpered. The differences measured between setups were close enough to follow a general trend line between products, and I worried that we would not have enough time left in the fastly waning balance of the afternoon to re-do all the testing to non-performance oriented aftermarket panel replacements, which do not compete with Banks offering, but which held a large part of my interest, which at that time also encompassed evaluating the restriction levels between the then newly introduced 3 inch panel filters vesus the ones half that thick that they replaced. All the data covering the new one inch extension of an internal barrier in the interior of the stock air box (to prevent damage to the filter media that a mod like the Zoodad clearly invites) was documented on those pages. Surely, we'd never have time to run all of those variations again.

"NO GOOD!," Banks bellowed.

He then relayed a sobering anecdote in an automotive engineering project he was involved with where a set of less than perfect data was saved, that later inadvertantly found it's way into the project... but only temporarily, as fortune would have it, because someone, very likely Banks, remembered that some bad data got stored before.

Of course I relented. I knew right from the moment of discovery that new data would be best. But I was suprised at the insistence of Gale that old data with potential flaws be completely DESTROYED. I'm a saver, so that's naturally hard for me. But Gale's point makes sense. There is no "just in case" justification for keeping data that has flaws that were not known at the time it was collected. I crossed out everything. Crumpled the pages. Fresh start. Fresh sheet of paper. Fresh new respect for Gale Banks, who I learned really does not futz around when it comes to image making, marketing, and precise testing.

We indexed marked the inlet to the flow bench machine, and indexed marked each and every airbox assembly such that the inlet was pointing in the exact same direction vertically in space, 180 degrees from the wall plane, and commenced retesting everything. It cost me an entire weekend stayover in Azuza. It cost Banks an entire unscheduled Monday on tying up his flow bench, which at that time was sorely needed for testing the head modifications on that 5.9B that later broke the world's fastest pickup record.

So the point to all of this is that a baffle in front of the snorkle has a regisiterable effect on measured flow at 25 inches of restriction. Modifying the baffle in some way will very likely make a difference. Whether that difference is a net benefit or detriment, considering all of the other usage factors and physical constraints associated with the area about that baffle, is beyond my ability to determine from the "good" data I have collected so far... as that data was not obtained via instrumentation wired in the truck.

That said, I'm trusting the engineers, and am leaving that baffle stock.

Not everything works as one would think it appears. While on the subject of Banks and flowbench testing, I'll mention another example. Many people who take delivery of Bank's Monster Exhaust systems, and install these systems themselves, are appalled to find that the entrance to the Dynaflow muffler has an insert in the inlet that makes the mean effective entrance to the muffler smaller than the exhaust tubing entering it. Appalled, many cry what's this restriction doing here? Some have even reported cutting the radiused curved, donut shaped metal ring out altogther, all while congratulating themselves on how they've "opened up their exhaust even better than Banks" and "removed an obvious restriction."

OK. Go for it. But before busting out the 4 inch hole saw, think about the trouble (design time, part production cost, labor time, inventory,) it takes to weld in that radiused donut "restriction," by an aftermarket, profit conscious, market savvy, successful entrepreneur whose entire business model has been centered around preaching opening exhaust and reducing restriction... for almost 50 years. That "restriction" in the muffler is "obvious" alright, because Banks put it there, and he used the same machine we were using to test these Superduty air filters to figure out that it was necessary for enhancing flow, not restricting it.

It's called a venturi.

When Banks was working on resolving a recurring issue with the Duramax 6.6L Monster Exhaust before it's release, he strapped the muffler to the flow bench, and used his team of engineer's and his own experience to sample various solutions... the final one being this little donut that some people see fit to remove while installing the system under their shadetree. The venturi increases the velocity of the gasses and expands them evenly into the muffler's chambers. The idea worked so well, Banks introduced it (after more testing) into the rest of the Monster Exhaust systems for Ford and Dodge.

The point is to simply reinforce what we always hear said, but what still takes a while to really believe... bigger isn't always better. Sometimes less is more.

Getting back to the intake air side of things, I'd be cautious about removing an inch from the AIS inlet snorkle. If material is removed at either end of the removal tube, the best parts of the snorkel would be lost. Cutting the back end, the retention tip that snaps into the housing would be gone, and trimming the front end, the more likely modification suggested, would loose the all important bugle-shaped radiused contour that is designed to smoothly draw in air.

Just more a little more fat (or gristle) to chew on this subject.