Operation IDIocracy: The Home Stretch! Single Battery Riser, Intake Path Machinations, and Turbo Piping Highlights

We’re getting awfully, awfully close to closing everything up here. Only a couple of annoying side quests remained after the Battle of the 73rd Brown Wire. One of them was where do I place the air intakes going into the turbos, which has actually been bugging me since the whole project started.

Snekvan’s temporary experiment nature meant that the underbody intakes were “kind of okay” as long as I avoided driving through deep puddles. For Vantruck that wouldn’t be acceptable at all. But where do I put the intake then!? The commercial solutions of yesteryear all had their air filters and intake boxes on top of the engine itself, or in the case of Spool Bus with its Banks-style system, it ran through a very long winding hose towards the front.

While I could have had plenty of space to put air filters on top of the block as well, then I’d have to run hoses down to the turbos, then back up. That seemed pointless, and having stuff up top would also defeat the purpose of leaving it open for service and maintenance access.

I came up with other creative ideas, going as far as to entertain side-mount air filter canisters for tractors (because actual air cleaner cans for semi trucks are far too large).

The Combination Battery Tray and Air Filter Housing

But one day while looking over the battery tray to modify it for my single battery conversion, I had a bright idea. Can you see it in the photo?

That’s right, Vantruck’s convenient fender apron rust hole, that it’s had forever, suddenly seemed like a great place to run an intake hose. This would put an air cleaner element right up front, just inside of the headlights on both sides, with the hosiery running down from this fender region and underneath to the turbos.

Suddenly it all made sense. To use a generic round filter, though, meant I had to raise the battery tray here several inches. Not a problem because I was having to remove it anyways to put a larger one on, but it might mean the battery comes awfully close to touching the hood from underheath. Only some fitment tests will tell!

I bought a set of spot weld cutters a while ago which came in handy for releasing the spot welds holding the battery tray on. That I had to do this at all was an annoyance. So far as I can tell, Spool Bus had bolt-in battery trays which I could have removed with some sockets. It seems like Ferd switched to a welded type at some point. Hell, the bolt holes were still even in the stamping.

The spot welds were not hard to find, even with the battery tray having rusted significantly. There’s two on each corner of the tray by where it meets the risers.

I bought this “OOOH WE PUT PLUS AND MINUS SIGN SHAPED DRAIN HOMES IN IT TO TELL YOU IT’S ELECTRICITY-THEMED” battery tray for Group 27 and 31 batteries. Interestingly enough, some of the slots lined up with the spot welds I drilled out.

The rise height I needed to use my generic 4″ OD x 7″ height cylindrical air filters was approximately 3 inches. That was basically the battery tray sitting right on top of it, such that if I had to remove the filter for cleaning or service, I’d have to remove the tray first. The lower constraint was having access to the screw to tighten or loosen the hose clamp retaining it on the future airbox/duct design I had to bake. Not a big deal, I decided, since I had made this riser design to be easily unbolted.

The riser is just made from pieces of 3 inch x 1 inch rectangular steel tube… incidentally, also purchased for Susquehanna Boxcar. The large holes allow a socket in to tighten bolts holding the risers to the original brackets, and the form-tapped holes towards the centerline are what fasten the tray to the risers.

Here’s how that looks. I’m using one set of holes in the stamped lower area of the tray, and one set of holes I drilled on the raised edge. This was necessary to position the battery itself for clearance to other things, so I couldn’t use the full set of stamped lower holes.

The bolt heads on the inner set would sit on the battery case directly. To prevent this, I’m just placing the battery on a 1/4″ or 3/8″ thick piece of something, like a plastic plate.

This is where the air filter will sit in general (it’ll actually be raised up a little, such that the neck fitting is visible). I now had to design a duct adapter of some sort that can let me securely fasten it while attaching it to intake piping at the bottom.

I pretty much just took some bounding dimensions of the bodywork in the area and made a big shell. The mount will be two pieces: An upper portion I’ll drop from the top that sits against the inside of the fenders and internal sheet metal, then a lower portion that attaches to it and fastens to the sheet metal from the outside.

A simple snap fit will join them, in lieu of having to drill a matching bolt pattern through the sheet and parts.

I prototyped the duct adapter/filter mount in some colorful PLA I had left over. A later revision before I made it out of “real” materials added a flange to the pink lower piece so I could arbitrary secure it to the fender aprons using some sheet metal screws.

This is the fitment as seen from the front. I cut out the little crossing sheet metal section that formerly divided this hole into two holes. Now it’s a singular large hole for BIGGER AIR.

When I liked the final geometry, I popped into the print farm at the lab and ran these parts using some Microcenter Special carbon fiber filled nylon I bought for the purpose. These towers were too tall for the Markforged Mark Twos, unfortunately (and honestly, I didn’t really want to waste Onyx money on these things…)

The setup gets duplicated on the driver’s side in almost the same place. The filter will sit between the windshield washer bottle and the headlights. There’s an access hole here as well, which I used as the basis for cutting an expanded hole around it following some OEM stamping lines.

This new trapezoidal cutout exposes the entire filter as well. To change it I can just reach in here with a stubby screwdriver after removing the grille.

The Combination Intake Pipe and Bump-stop

If the air filter placement was funny, the intake hose routing is going to enter the realm of the absurd. See, if I didn’t want to figure out how to route it up inside the wheelwells (which are going to be very tight given the van steering geometry.

The next best place is simply mounting them through the suspension swingarms.

I used a length of silicone intake piping (for high rebound and resilience properties!) mounted with couplers on the end, made using my new tubing bead roller. The piping sits high enough that I think if the suspension compresses to the point, I have more to worry about than a small intake restriction.

A length of flexible duct brings the air filter housing to the Combination Intake Pipe and Bump Stop. Behind that, a length of similar duct connects to the turbos.

The silicone pipes are retained by these clamp mounts that I designed. The mounts are drilled into the engine cross-member and tightly snap onto the pipe outer diameter.

This was a simple straight run on the passenger side, but the driver’s side needed some more thought. First, I planned to inject the PCV valve exhaust here. Because the turbo sat slightly offset with respect to where the CIP/BS was going to run, it was easy enough to design up an elbow coupler with a small secondary N I P P L E for the PCV hose.

A quick PLA test print for fitment. I made a geometry revision, then busted it out using the same carbon fiber filled nylon.

On the front end, I made another 60 degree elbow to bring the intake ducting away from the swing of the steering gearbox first.

And this is what the final configuration looks like! The driver’s side duct swings farther out because of the aforementioned clearance to the steering gearbox and link.

Overall, I was super thrilled about how stealthy and integrated the intakes ended up being. You can’t tell from the outside that anything’s been changed about Vantruck at all. There’s no pipes sticking out from the hood or a scoop or anything (though…. I’m not opposed to a hood scoop even though it doesn’t take air from there, it would still afford more cooling airflow and could let me position an intercooler up front as well)

Hmm. Vantruck turned into a sleeper build, for extremely broad definitions of “sleeper”. Maybe it’s just asleep.

Some highlights from the rest of the hosiery

I’m not going to deep-dive on the fabrication of the new turbo pipes and whatnot, because they largely followed the pattern of Snekvan. Here’s just some select photos showing what whacky things I did on this front.

The intake adapter this time wasn’t 3D printed. It was fun to do before, and it didn’t not work, but I think for longevity and peace of mind I’ll stick with a metal one.

The top of the IDI intake event horizon is 5 inches in diameter, so I just crafted a dual intake adapter from a chunk of 5″ pipe I had, probably from some Overhaul thing that never materialized. The Schedule 40 pipe is ridiculously overkill, but it fit!

To this chunk of pipe I added two 2″ pipe stumps with rolled beads for fastening the charge air hose to, as well as a few weld-on 1/8″ NPT fittings I had. The lid was a bandsaw-cut circle of 1/8″ thick steel welded to the pipe. I chucked it in tinylathe and cleaned the edges up post-welding so it looked round and intentional.

And… of course, you know what happened next.

For the turbo downpipes, I went ahead and bought some tight-radius mandrel bends. The thing is, nobody really makes plain steel mandrel bent elbows like this…. because why would you? I ended up again with a half-stainless and half-cheese steel exhaust. I really don’t like how the 309 wire you use to join mild steel to stainless steel handles on my welder. But it is what it is!

One of the innovations this time was the Egg Flange:

This is to make the extra tight turn on the passenger side downpipe, the thing I made last time using a machined piece of actual pipe elbow. I think this is only slightly less terroristic.

To generate the Egg Flange, I basically redrew what the mandrel-bend stainless steel elbow looked like and then sectioned it using a plane that was almost touching one leg of it tangentially. This is the virtual equivalent of sticking it in my bandsaw sideways (see the saw marks where I put it just a little too sideways on the left). I then copied that egg-shaped cross section and made a flange plate from it.

The Egg Flanges were sent out to be made along with some regular T3-to-2.25 inch flanges. These are 3/8″ steel from SendCutSend, lover of BattleBot builders.

Here’s the completed turbo pipe assemblies now. Excuse the welding – like I said, I went for dirty and penetrative rather than carefully TIG welded. It was not hard to blow holes through the metal because I only had 0.035 wire and supplies for Limewelder. 0.025″ wire and nozzles would have made for a better time. The ball flanges were made from the same Walker 61725 stumps welded to the mandrel-bent tubing, then to my flanges.

Check this photo of the fully reassembled engine, ready for the first test fire!

Operation IDIocracy achieved first light-off in late April after these harrowing last few weeks of work. This wasn’t too difficult, since each of the components had already been tested separately or in blocks. For now, Vantruck could at least get out of its own way if needed, such as if I found a New Robot Trap House much sooner than anticipated. There were a lot of unaddressed issues and bugs that I decided to leave for later. The month of May saw some of these bug patches and changes, which I’ll touch upon the roundup post next!