GrimmSpeed 2015 - 2018 Subaru WRX / STI Stealthbox Air Intake - Red/Black
Inspiration for the StealthBox Intake came from internal discussions about what we wanted from an intake system for the 2015+ WRX. Of course performance is the highest priority, but at GrimmSpeed so much more than that goes into a product. We wanted an intake that purred quietly under normal driving circumstances, but would roar at wide open throttle. We wanted an intake that looked at home in the well-sported 2015+ WRX engine bay instead of a shoebox stuffed into the fender area. From here, the SteathBox was born. We took the concept one step further and referenced the F-117 Nighthawk as inspiration for the stealthy look of the GrimmSpeed heat shield. It should come as no surprise that the performance it packs is equally unique. MAF diameter and placement, total bend angle, filter location, and heat shield design were the primary variables during the design phase. To ensure accurate readings, unaffected by the intense heat of the engine bay, MAF sensor placement absolutely must be within the heat shield. To minimize restriction, it was important to keep the total bend angle in the intake tube as low as possible, but still raise the filter location away from the ground to protect it from the elements. Lastly, testing showed the importance of utilizing the factory ram air scoop to feed the otherwise stagnant air in front of the fender.
Each intake begins with a CNC bent and laser cut 6061 Aluminum tube. Contrary to popular belief, particularly from those producing composite intakes, we found that the increased thermal mass of using thicker aluminum tubing (1/8????? wall thickness) kept the intake from being vulnerable to rapid temperature change. This is called the 'thermal flywheel effect' and will keep the rapidly fluctuating temperatures inside your engine bay from affecting intake temps as drastically. Custom MAF flanges are machined from the same 6061 alloy and are placed on the straight nearest the filter, where we observed the most consistent cross-sectional flow. Mounting brackets are laser cut from 3/16????? thick aluminum plate and CNC bent for perfect and repeatable fitment. Finally, heat shields are laser cut, CNC bent and hand assembled before going to powdercoating for a durable wrinkle black finish.
The GrimmSpeed intake produced an additional 32ftlb (14.3%) at 3000rpm and 21whp (9.6%) at 5500rpm, with healthy gains all the way across both curves. As mentioned before, the AFR and Boost curves are also included to demonstrate that the gains shown are from the intake alone, not the manipulation of other variables.
- +32wtq (14.3%) and +21whp (9.6%)
- Designed in CAD - Perfect mating with the factory turbo and ram-air scoop
- Low bend angle aluminum tube - Minimize restriction and maximize performance
- Shielded MAF sensor placement - Protects MAF from heat, which increases accuracy of readings
- Made in the USA - Manufactured right here in Minnesota
- 1x CNC bent intake tube with MAF flange
- 1x GrimmSpeed high-flow air filter
- 1x Aluminum heat shield
- 1x 12" MAF harness extension
- 1x Silicon hump coupler
- 3x Stainless steel worm gear clamp
- 3x Rubber gasket material cut-to-length
- 2x MAF sensor machine screws
- As with any intake, tuning is required after installation to maximize gains and safety.
- Take care to install the air filter onto the intake tube properly. Push the filter onto the tube no more than 1" before tightening the clamp. This will ensure that the velocity stack within the filter is allowed to function properly!
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