Custom Air Filter

The K AND N ENGINEERING Custom Air Filter Model E-3988 is engineered for drivers and mechanics who demand measurable improvements in engine breathing and overall vehicle performance. This reusable high-flow air filter replaces restrictive OEM filters that gradually accumulate dust and debris, reducing intake efficiency over time. Whether you're building a performance street machine, tuning a daily driver, or maintaining fleet vehicles, upgrading to a custom K&N filter addresses a fundamental bottleneck in any engine's fuel and air mixture calibration.

K&N's proprietary cotton-gauze media design allows significantly greater airflow compared to cellulose paper alternatives, reducing intake restriction without sacrificing filtration. The pleated synthetic frame and precision-engineered housing ensure consistent air velocity across the filter surface, maximizing volumetric efficiency in the intake manifold. This custom filter measures 8 x 3 x 10.625 inches and weighs only 1.08 lbs, allowing direct installation in factory air-box locations while maintaining proper seal integrity. The washable, reusable construction means you replace the filter once every 50,000 miles with a simple cleaning kit—eliminating recurring filter purchases and reducing waste over the vehicle's service life.

Mechanics and performance enthusiasts rely on K&N custom air filters for turbocharged and naturally aspirated engines where intake flow is critical to dyno-measured horsepower and torque gains. Installation requires no modifications to existing air-box assemblies—the compact footprint and standard fitment dimensions ensure bolt-in compatibility. Paired with tuning adjustments to the engine control unit or carburetor calibration, this filter maximizes the breathing potential of your intake system. For street applications, racing builds, or routine maintenance upgrades, the E-3988 delivers consistent, measurable performance without compromise.