Built to Breathe: The First Tri-Snorkel Airbox for the Mkiv Toyota Supra
🔥 INTRO: “It Started With a Scan”
Every detail began with a 3D scan - a raw capture of my personal Toyota Supra’s engine bay.
What followed was a simple question:
What would a Modern Airbox looked like, if it were designed today -
For a Single-Turbo 2JZ Supra Equipped with a modern turbocharger, chasing four-digit horsepower - While respecting the DNA of the original car?
The answer became WangSpec's Airbox:
Tri-Snorkel. 10-litres of internal volume. Engineered for maximum flow, using every millimeters of surrounding real estate.
🔍 The Concept: Fit First, Then Flow
Every great airbox starts with boundaries.
We began by tracing the available floor space - testing various shapes and layouts to see what was possible.
Once the geometry was defined, the next challenge was finding a filter that could match our airflow goals without exceeding the physical limits of the bay.
After testing both panel and cone-style filters, we landed on a winner:
A 6-inch K&N cone - known for supporting four-digit power builds while maintaining low restriction, and just enough vacuum to keep factory crankcase evacuation systems happy.
This filter wasn’t chosen at random.
It was the only one that fit our dimensional constraints and held up against our airflow goals without choking off power where it mattered most.
🧬 Inspired by OEM — Evolved for Boost
The factory Supra airbox is genuinely well-engineered.
Its dual-snorkel design uses:
- One inlet above the radiator
- Another tucked under the RH headlight
Internally, it even features flow diffusers - a detail many overlook.
Together, they do a solid job for stock to mild builds.
But once you step into the world of single-turbo conversions, the story changes.
The stock panel filter and limited volume become a bottleneck - especially on setups pushing serious power.
We noticed a common trend:
Many single-turbo Supras reroute the intercooler piping into a drop-down layout, leaving the old SMIC piping opening unused.
That opening was a gift - a factory airflow path that was going to waste.
That’s when the idea hit:
What if we made that the third snorkel?
No cutting.
No sketchy ducting.
Just clean, OEM-inspired airflow from a hole Toyota already gave us - now repurposed with intention.
🔧 Designing for Real-World Fitment
Once the tri-snorkel idea was locked in, it was time to translate the idea into hardware.
Using CAD and 3D scan data, we began shaping the airbox volume - prioritizing internal airflow, but also making sure it could physically fit. Sounds simple, but the upper section needed to allow a 6" air filter to actually slide in and clamp down, which meant every millimeter of clearance mattered.
At one point, we tried modeling the stock radiator snorkel just to test geometry. It wasn’t cutting it - both in airflow and aesthetics. So we scrapped it and started designing our own snorkel from scratch.
Even now, the cone filter requires slight flex at the rear flange just to install. Not because we wanted to make life harder, but because that’s what it took to squeeze a 6” filter into this engine bay without cutting into sheet metal.
🔬 Shaping the Radiator Snorkel
After careful consideration of the surrounding real estate of the airbox, we have decided to side mount the entrance of the radiator snorkel, instead of having a pass through up top like OEM.
Modeling the entry shape at the airbox required careful planning, as we needed sufficient clearance to the stock radiator fan shroud.
By keeping the connection shape round, and slide fit, this would allow tolerances for a variety of aftermarket radiator with varying sized radiator heights.
After testing multiple models to verify hood clearance, we have finalized the shape of the radiator mounted snorkel, with internal vanes added. This would retain rigidity, and reduce a small amount of inlet turbulance.
Additionally, the bolt hole on the radiator snorkel is slotted to account for tolerance within a variety of aftermarket radiators.
By finalizing this design, this would allow us to simplify the top lid, and simultaneously maximize air filter, and hood clearance.
We have concluded the top lid to be water-jet cut out of transluscent polycarbonate, to expose the air filter for a powerful appearance, without compromising the purpose of a sealed airbox.
🧱 No Supports, No Problem: The Flat Floor Trick
The underside of the airbox presented a challenge - The mounting location sits above a structural crush zone in the engine bay, meaning the floor couldn’t be completely flat.
To solve this, we added a bolt-on extension plug.
This component does double duty:
- It acts as a spacer to bridge the uneven geometry beneath the box
- It keeps the bottom support-free - reducing cost and eliminating support blemishes from post-processing
The center hole of the plug is pass through, and accepts a M6 bolt, allowing the airbox to mount to an OEM-threaded hole on the chassis. This Minimalistic solution allows us to maximize the box's internal volume and eliminates the factory Toyota Air Box Bracket.
🌀 Completing the Trifecta: The SMIC & Headlight Snorkel
The final two snorkels complete the airflow puzzle.
First, the SMIC snorkel: repurposing the factory side-mount intercooler opening that is now unused in most single-turbo setups - we designed a custom duct that captures ambient air from a forgotten spot.
The shape was created with a smooth transition, with a straight path into the Air Box. No trimming, no drama.
Next up, the headlight snorkel: originally, Toyota used an extended duct to channel air from under the RH headlight into the stock airbox. Our version simplifies that flow path by eliminating the extension, and instead maximizes direct inlet surface area using every spare millimeter from our 3D scan. It’s cleaner, tighter, and optimized for modern performance.
Together with the radiator snorkel, these inlets form a tri-force of airflow - each with its own dedicated channel, engineered to supply serious volume while preserving OEM integrity.
🔧 Fitment Comes First
Here’s a quick look at our first PETG prototype of our "Type A" Variant in place - showing just how tightly everything comes together.
More to come in Part 2: Simulations, Type A vs Type B variants, and O-ring solution.
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Stay Tuned!