This thread posting has been long overdue (from me), but the delay has allowed a chapter or two more to be written. So here goes..

I know we have had and still do have a number of better breathing products for the Magnum engines--14x3 setups, K&N et al drop-in filters, K&N/Volant/Ebay/DIY complete systems--and know (and have read) the numerous threads regarding the best 'cold air intakes', what a CAI is, filtering quality of paper vs aftermarket dry and oiled setups, the whole bit. So I'll add a twist to things. I picked up a 3D printer last year with the primary purposes of being able to print a variety of plastics, chief among them being high temp for under-hood applications, as well as to make something that could be sold to other people. Plenty of people 3D print toys and trinkets, and have for years, which is fine, but I wasn't about to drop real money to enter that space.

The Magnum trio of engines, as we know, use the two-piece clamshell filter box / intake-elbow-to-throttle-body. Due to accounting, engineering, production capability, and vehicular ease-of-assembly reasons, the filter box and lateral intake tube (to the fender) setup was created. I'm sure all of us have looked at the top half and seen the half ski jump / half choke point the air from the filter must navigate as it works toward the open throttle blades. Not ideal!

The aforementioned aftermarket solutions address airflow (or perhaps more specifically, the ability for linear airflow) into the TB/venturis to a decent degree, and by that I mean they they take the situation from a 1 or 2 (out of 10) with the factory setup, to a 5 or 6 by giving the incoming air enough space to figure a decent way into the engine. But what about a truly optimized, very directed path? Would it work? Would it be worth it? Could I design an elbow (essentially) that worked with off-the-shelf or aftermarket pieces. Could a solution look OEM or close, instead of aftermarket? [Note, there is nothing wrong with an aftermarket aesthetic--people's preferences can be for either OEM or aftermarket for any number of reasons]

A year ago when I bought the truck, I found a considerable mouse house in my intake tract (pre filter), and replaced that old filter with a new paper filter. Shortly after that I had more mice inhabiting the tract, so I fashioned a grate at the start of the lateral tube and have been in the clear ever since. At that time, I decided to go with a K&N drop-in filter to help the old 5.9 out [I am not here to debate or discuss paper vs oil vs engine life, just to get that out of the way] and save some time and money. There was an improvement in breathing via butt dyno, but it was very minor.

So I set about designing an intake elbow that would perfectly direct air into each venturi plus have an accommodation for the IAC circuit. Old (OBS-era-ish) Ford 351's and 460's have those dual intake pipe paths from the filter to the TB blades, so this would be similar, albeit considerably shorter. My CFD work consisted of looking at a number of HVAC ducting CFD examples (air pressure and air speed illustrations) via Google Image search. I considered directing vanes vs fully smooth flow, bend radii, etc and took the logical (what I call) "railroad tracks" approach to airflow: just make it as smooth and easy as possible in the given space constraints under the hood.

Below were some initial CAD designs that worked with the stock Holley TB/TB plate and clamping systems. They had 4" pipe couplings for use with aftermarket-available intake components that one could find in-store or online (like via Summit). None of these made it, but were part of the process (post #2 has the first produced product).

The path from the TB to the coupling was a simple 90° bend into the large opening. Lovely flow for that 90° part with the air having to funnel itself to either channel pretty quickly. The dark triangle at the top is the path to the IAC valve at the back of the TB plate.



The air path is nice here, clearing the TB parts while ducking the drape/weatherstripping at the base of the cowl. You can see the flare to the coupling. That part needed work.


This development (V2, officially) was my taking the necessary 90° turn to the side into my hands. No need for a separate 90° elbow and coupling hardware--the fewer parts the better. It looked even weirder, and I hadn't even considered how or if it could be 3D printed, let alone produced in metal!


This is actually V4 as I was developing V3 alongside it, but this version goes into the bin of ideas that weren't produced. This design gave more thought to how it would be 3D printed, but there was MUCH to consider and figure out. V4 was aimed at cribbing some componentry from a K&N or similar example that angled off the TB. Combine V4's better better flow for that 90° turn while using the rest of somebody else's design (at least before I came up with my own kit). That'd be double dipping on intake part/kit purchases, so this line of thinking was abandoned. But hey, it's rendered in matte black so it looks official!


I top down angle here, showing that sort of "appendix" form that is actually the IAC valve/circuit provision.

 

I eventually had the thought: "Why don't I simply make a better top half of the intake box? Take the cost and production limitations of injection molding plastic on a large scale, and replace them with the ability of a custom 3D-printed solution?"

The first model was a near-replication of the current top half/top hat, but with a vastly-improved filter-to-venturi path. I really liked it. In my complete, blissful ignorance to any limitations to 3D printing (in plastic or metal), I sent the model out for some quotes. I received one response, for over $1400. Well now.... I think I could buy a 3D printer, high temp filament, and make one for the same or less than that. So I took a big gulp and ordered the printer and filament. I made updates to the 3D model to break it into smaller parts that worked within the print space limitations of the 3D printer. Still quite ignorant, but at least acknowledging physics.

Slicing the model up was difficult as I had to consider ease of assembly, strength of the piece, tool access, and those four rectangular slots that the lower half of the filter box interfaces with. The filter interface on the top half, as well as the over-the-filter "skirt" around it were all lifted directly from 3D-scanned and caliper-measured data. This is a complicated piece Dodge designed--many things to consider!


I printed out some test pieces of basic filament/plastic to at least get some idea of how easy or not it would be to print "any shape I wanted." One of those pieces was an 80mm tube that was 2mm thick, laid on its side. It'd be a cinch to print the tube vertically, with guaranteed success, but what about overhangs? Would they need support? And if so how much? Would those supports be easy to remove after printing? Turns out that supports would be very necessary, and at a lot less extreme an overhang angle than the standard settings of the printing software specified. Oh, boy, this is going to be an uphill battle.

Looking at the above model I'd made, I knew that printed support material would be everywhere and that would be hell to deal with. I might as well just sign myself up to be an archeologist. I determined any styling or aesthetic consideration would have to take a big ol' back seat to the mission of "No support at all cost...or if there must be, it must be absolutely minimal." This directive, while a good one, proved incredibly difficult to execute. Round passages turning 90°, with strength, space constraint, dimensional accuracy, and material consumption concerns at every point in the design.

Finally, success. It would be many pieces, with much hardware holding it together, but it would exist and give my Better Airflow Path idea the chance to succeed or fail.

Let's look at what I affectionately call The Pizza Box Intake, albeit without parting lines:



This is like a suuuuuuuper low rent version of the computing-power-limited design of the F-117 Stealth, where one considerable limitation was the primary design factor. Chunky boy, indeed.


Cutaway to see the trapezoidal to-the-venturi runners (well, the start of them). This is what the air filter "sees." The trapezoidal shape morphs to circular at the venturi. The area of this opening is considerably larger than the area of the choke point in the factory airbox top.


Ok, a glam shot where you can see all the pieces in a semi-confusing fashion! There is a central spine that brings the two big hat pieces together while also guiding air into the two channels.

 

So now for the fun part. Printing and waiting for prints to get done, plus "tapping" of printed holes and continued assembly. The final tally for print time came to a whopping 44 hours. That is a lot of material and a lot of time! A few 11-12 hour single print sessions in there. It's really cool to see them come to life. Printer moves quickly and makes many humorous sounds.

Onto photos. This is a removable and cleanable print plate, and one uses a literal kids glue stick to help the printed model release cleanly/easily from the plate. An 'apron' is printed around the piece to keep it in its place while printing. It's a large apron, and more necessary for tall pieces (apparently), but worked just fine here. You can also see the whisker-like or extra textured aesthetic of this print. These high temp plastics (carbon fiber-infused in this case) need to be dried out at about 180° F for 10-ish hours. There seems to be no performance degradation in the plastic, but it does bulk the piece up ever so slightly in addition to having considerable extra texture. This "extra" would come to be the bane of my existence as I went to assemble everything.


Here we have the base plate (interfaces with the Holley TB plate), venturi guide piece (installed inside the base plate, matches to the venturis exactly), the main air passage/frame piece (center), center-of-box stiffening bracket (center top), the air passage tops (left, lower left), and finally the air box latch interface tabs.


Pieces fitted after a lot of sanding and filing, laid out in their planned orientation.


Underside view of the air passages that come to meet the venturis, with the center venturi guide 180° out of phase (no detriment to the primary airflow mission). You can see the port for the IAC valve flow. In the above photo, you can see the two 'nostrils' in the center at the base of the trapezoidal air channel openings. Those nostrils lead down a winding path around the main air channels, maintaining a minimal size to allow the IAC valve to operate properly and not be starved of air. Casting would get this job done, maybe, but 3D printing's capabilities were definitely employed to considerable benefit here.


Between flathead M5 screws and black RTV, the first bulk section is complete!

 

At this point, certain pieces for the primary air passages were initially and individually sanded via "sanding ball" and Dremel. Now that they were assembled, I worked to blend them to make as smooth an air passage as I could. There are small gaps in the seams, and that's largely due to "where is this hanging up???" Making mental notes to put some gap in the pieces (in CAD) so that there's enough wiggle room and room for the RTV to not have to hack at things so much.



At least this part turned out beautifully!


12 hour print, with a whole lotta support to remove. It was a battle.


Another view of "the wal" and the "tree" supports. This was the orientation of the piece when I printed it. No supports needed for the bulk of it. I broke my no-supports rule for reasons of maintaining strength (of the piece) in a critical part (the force that the rectangular slots would take when clamping both halves of the intake box together). I was also just wanting to get it done, lol.


Finally got everything cleaned out!


Getting close!

 

I ran into some delays with the last piece, needing to order more filament to complete the print. This whole thing was a saga, but I got it done.

Here's a great A-B comparison. The factory piece is (understandably) considerably lighter--my piece has heft. Both pieces are very stiff and strong.


Some of the Ugly here in this process. I made sure, in this design, that there were no screws that could come loose and get sucked into the engine, but just for the DIY guys and gals among us, this 3D printing is pretty awesome, but there is a learning curve and getting it right the first time is far from a guarantee, let alone should be an expectation, even if that was my goal.


View of the airflow path. It is considerably better than factory. This has to work, dang it.


The print's overall accuracy was really good, and after some extra filing to get the lower half to slot into the upper's holes, the two halves clamped together straight away. Whew!


Pizza Box installed. I did have to do some clearancing of the base plate. I somehow didn't fully account for the bolts that fastened the TB to the Kegger and had to hog out some of the plastic.


Another view, because why not?


It blends in about as good as it can, primarily thanks to it being black and having OEM fitment. Otherwise, it's pretty obvious that it's not like the others, haha. Really happy that all the measurements for spatial constraints paid off. Only the top forward edges contacted the (newer) under-hood lining and dug in some witness grooves.

 

This was the big question. Was my idea and fly-by-night "CFD analysis" worth anything? Thankfully, yes! I had been making a chart of my incremental progress in this department. Obviously the stock air box upper had poor flow, and a factory-spec paper filter was restrictive. The K&N drop-in filter helped a little, but there was more to go.

***And I should say, I fully aware this is a small cam legacy-block engine built for truck duty. I've read plenty of threads and articles where people try to get these to breathe some fire and it's a lot of effort for not as much return. But I love these old 360/Magnums, and this is a fun project that could truly be beneficial to the truck. I just want the thing to not struggle for air so much, and this is low-hanging fruit.***

There had always been this "power trough" (as I called it) where, past the initial revs to get the truck moving, it was this barren wasteland until about 3000 RPM where the motor really felt like it came on cam before getting a bit winded at 4000 and higher. The Pizza Box did a few really nice things. Firstly, it really smoothed out the throttle tip-in, which noticeably improved starting from stops and in-traffic on/off throttle work. The truck was more than acceptable before, but wow it got even better. Secondly, it reduced the "power trough" considerably while adding an in-gear, in-city eagerness--think 3rd gear at 27 mph in a neighborhood--that wasn't there before. And that's half of what I was looking for here. I want a vehicle to want to be alive and to do things. I don't need it rocket ship fast, but I would like it willing. Lastly, I did gain top-end (~4000 RPM and higher) breathability. This may not really show up on a dyno as some noticeable peak power improvement, but it helped and seemed quicker to 60 (at 80% throttle) than before, in addition to all the below-peak power and drivability gains.

As far as mileage, this all happened as we've headed into the winter season with lovely winter blend gas. Mileage hasn't improved, but neither has it worsened. I'm around 12 mpg combined and up to 15.5 on the highway (had some payload, and there were 20-30(?) city miles in there). The truck does pretty well for itself, and that's fairly normal driving--no hotrodding or hypermiling.

Towing seems ultimately unaffected. Honestly, it's hard to discern if the easier drivability is a loss of some low-end torque, or if it is shining light on the fact that, with the factory box top, I always needed to give it more gas to get the same result when getting off the line or maintaining speed around 1600 RPM. I've looked a lot more intently at OEM intake setups while at the Pick-n-Pull, and regardless of era, intake tract architecture is all over the place. Some companies will have a volume of air, post-filter, available to be immediately sucked in before having to draw air through the filter (think 14x3). Others have a long pipe (or pipes) from the throttle blades to a fender-mounted filter box (Ford 351/460). The latter architecture is employed almost exclusively today, and has been for the last 20 years. Unloaded, again, there is more pep everywhere.

*****

But even with this success, I was thinking about the next step...

 

V3 was a great proof of concept, and I could have run it in perpetuity, but as a product to potentially sell? No way. For many production-related reasons. So, back to dreaming something else up.

And here we are: a '15 Ram 1500 5.7L Hemi intake assembly. Drove nearly an hour each way with a feeling of "Well, here we go, hope this works!" Got it for a good price, with a (pretty dirty) paper filter in it.


Doing some initial fitting. I determined I'd have to cut the hose and clock it 90° to make it work at the very least, but once again, it looked like that could really work.


Ideally, it would have been nice to tuck the newer filter box up next to the fender--not unlike the Cummins' filter boxes in this gen do--but the filter box, fender, and hood weren't cooperating, so I had to shift it inward. This also helped the snaking intake hose reach situation. I'd need to make mounting brackets to secure this box, another measure ten times, print once (hopefully) situation.


Yup, going to use that hole for mounting a bracket...


More good news: this hose will end up about where I need it to (once I design and print an intake elbow for it)!


Getting a bit crowded with all this filtration and ducting, I tell you! Fun fact, that one/two years the 3rd gen Rams used the 5.9 Magnum, they used this air box design and that size filter. The filter part number is the same! Those 2002/2003 Rams had a flexy hose/elbow combination that looks, in pictures, to flow better than our second gen setups, but Dodge still rated the 5.9's at 245 hp. Anyway, I kind of got a kick out of the proverbial baton-passing / parts lineage. This intake box was also used on the V10-equipped 3rd gen 2500/3500s. The hose comes out on the left, then makes this biiiiiig, obvious loop to the left before doing a hard jog to meet the air box opening. Total makeshift stuff, but understandable.

 

I was determined to make this Version 5.0 intake elbow much simpler than V3.0 (3.3 by the time I was done with it). An updated base plate and venturi guide piece would still be present, but everything above them would go from nearly a dozen pieces to just two. I now couldn't get the filament I wanted (PET-CF, specifically), but I was able to snag its nearly-as-high-temp-capable brother, PA6-CF. It's capable of handling (heat deflection) over 360° F, and after several hand-on-intake-piece tests, the base of my intakes only get to 85-90° at best after a long drive. Great news.

This rendered image is a bit out of order, but it is the final of what I came up with. Intake elbow on the left, main air box locating bracket at top, intake pipe coupling at right, secondary air box locating bracket (bottom), Hemi air box PCV hose plug (by elbow), and Hemi intake hose port adapter (for Magnum PCV hose).


Print of the lower main half of the elbow. You can see the layering that would need to be sanded and smoothed. You can also get an idea for the airflow situation into the venturis once that was all done.


Top main half of the elbow. That tab would have a bolt going through it to secure it to the lower main half (in addition to the other hardware that you can see provisions for).

 

Thanks to my updated base plate design, this new elbow dropped right onto the TB plate. That felt really good.

But first, an empty-ish engine bay..


Intake elbow placed. Insides are smoothed and the passages line up perfectly with the venturis. That also felt good.


Sitting on its gaskets. So much space in front of it!


Clamped down to the TB plate.


Uh oh! I broke the upper main half trying to gently wrestle the main hose onto the elbow (my fault). A design revision, some extra sanding, and making sure that all hardware was in place now had me good to go.


Complete! Everybody was "holding hands" and it was now time to test drive!

 

With many not original-to-the-truck pieces, I was bound to have a few issues. That and a dirty paper filter. The test driving yielded generally good results. The dirty filter was killing power, that was felt. But the power delivery was even smoother and more linear, with a near-elimination of the "power trough." Engine temps were great, drivability was great. I knew I had to do something about that filter as well as address the problem areas that had manifested themselves.

Guy lived on a dirt and gravel road. The filter did its job.


The coupling I'd printed out of PLA needed to be longer, and the stainless steel "wire ties" had trouble gripping this portion of the pipe (the best place to cut and clock). Dremel'ed in grooves in the rubber on both sides would have helped.


Measure once, work the mounting, break the cheap 3D-printed plastic secondary mount. Oh well...


At least this mount came out pretty good! Well, minus the need for duct tape shimming for the aft plug and bolt-to-chassis mounting.


My initial PCV conversion port printed too small (darn PLA plastic!), and I needed to use some old radiator hose to go over the Ram's PCV hose and then over this duct tape-shimmed port.


At least the air gap was good between air box and engine! Also, duct tape covering the Hemi PCV hose port.