Performance Gains: 10–14 hp, 10–11 ft-lb
The GR86 intake is the culmination of over 125 dyno tests across various configurations to arrive at an optimized design. We tested both stock and tuned vehicles to evaluate the impact of switching to a less restrictive intake version. As the naturally aspirated 2.4L boxer engine is sensitive to intake air temperatures, our initial priority was to ensure a fully sealed system. Dyno testing revealed that the stock ECU causes a power drop around 6000 rpm. This power drop persists regardless of the intake configuration. Even with all restrictions removed, the high airflow volume causes strong engine resonance at this rpm, resulting in a momentary power drop below the stock curve. The stock airbox provides a mysterious benefit at this rpm, but it also restricts power at higher rpm. After iteratively testing various intake lengths, single and dual duct openings, and even the addition of baffles, we arrived at a version that minimizes the resonance dip while increasing peak power by 14 hp on the stock ECU. Tuning the ECU results in significant power gains in the mid-range and eliminates the power drop below the stock curve.
The Eventuri Difference
The GR86 Eventuri system utilizes our patented carbon fiber housing, providing an aerodynamically efficient airflow path from the filter to the turbo. This is not just a cone filter with a heat shield; it is a unique design that induces the Venturi effect and maintains laminar flow to reduce turbo drag. Please see here for more details on the design and mechanics of the housing.
The filter housing consists of a bespoke second-generation filter, an aluminum inlet cowl, and an integrated airflow section. The carbon pod covers a reverse-mounted filter, smoothing the airflow to the airflow section and connecting to the rear inlet tube. This changes the airflow path from the stock airbox. Airflow entering from the front of the airbox makes a 90-degree turn to pass through the panel filter, then another 90-degree turn to pass through the airflow section. Our system achieves a more direct flow because the airflow enters from the front of the filter housing and flows to the airflow section without sharp directional changes. As a result, the airflow path from the filter to the turbo inlet tube is smoother, reducing turbo drag. We use a CNC-machined mount fixed to the carbon housing to ensure a secure seal with the mass airflow sensor.
The ducts channel ambient air from the front bumper/grille section into the filter housing. After several trials, we found that a dual intake that draws cold air from both openings in the slam panel area works most efficiently. The front bumper area is filled with cold air from our scoops and the natural design of the stock cavity behind the bumper. The ducts feature extended rubber seals that integrate with the filter housing to prevent hot engine bay air from entering the intake while allowing for engine movement. It is mounted in three positions for a secure fit.
The final components are two front scoops located behind the lower grille, which direct ambient air upwards into the duct openings. This keeps IAT (Intake Air Temperature) low while driving. Even if you cannot use the scoops due to an aftermarket oil cooler, the IAT is kept to a minimum as the air behind the bumper is naturally saturated with cold air.
Note: The engine cover is not included with the intake system.
Each intake system includes:
- Patented carbon fiber Venturi filter housing (with integrated airflow section)
- Bespoke high-flow dry cone filter
- Carbon fiber dual-feed inlet duct
- Laser-cut front air scoops
- Custom-made hardware
- Laser-cut stainless steel brackets
- CNC-machined MAF boss and bracket mount
Before Ordering
〇 About Import Consumption Tax
At the Shaftoya shopping site, we pay the import consumption tax incurred at the time of import on your behalf, so there are no additional charges beyond the total amount paid at checkout.
〇 Confirmation of Compatibility
Our entire product database is based on North American vehicles (USDM). Please verify whether the product can be installed on a Japanese vehicle (JDM) before placing your order. (Please feel free to contact us if you are unsure if the listed product is compatible with your vehicle; our support team will investigate for you.)
If you place an order without confirming compatibility, we cannot accept returns due to incompatibility.
Please note that even if a product is sorted by selecting the year, manufacturer, and vehicle model on the tabs on our top page, it does not necessarily mean it will fit a Japanese model vehicle without modification.
All products are translated into Japanese using translation software. There may be confusing expressions, so please contact us before ordering if you have any questions.
○ Regarding Shipping
Shipping costs are paid at the time of checkout. Shipping estimates are calculated automatically when you enter your shipping address on the checkout page. For large items such as body parts, the actual shipping cost may occasionally differ significantly from the automated calculation. In such cases, we will contact you individually via email.
All products are essentially shipped internationally from our US warehouse. Unlike domestic shipping in Japan, international shipping takes about 7 to 14 days, so please allow yourself plenty of time when ordering. If you are in a hurry, please contact us in advance to confirm the delivery date. All products are transported via air freight. They are not shipped by sea.
○ Regarding Japanese Vehicle Inspection Compatibility
Please note that all products we handle are designed and manufactured outside of Japan. They are not compliant with "Japanese vehicle inspection standards," and we cannot provide structural calculation documents or similar paperwork for the Japanese inspection system. Therefore, all parts are sold for the purpose of "use on circuits, private property, or off-road," and installation and use are at your own risk.
○ Regarding Warranty
Please check the contents immediately upon arrival. Since all products are shipped internationally from outside Japan, there may be shipping damage to the packing box or the product. We will only provide returns, refunds, or exchanges if you contact us within 7 days of receipt regarding damaged products, defective products, or incorrect items. Please understand that for products sold through us, warranty support will be provided "only through us." Please note that we do not handle support through other companies or agencies located within Japan.