Universal Air Filters nT 6inH

The K and N Engineering Universal Air Filters nT 6inH (model RU-5173) represents a trusted solution for engine builders, weekend mechanics, and daily-driver enthusiasts seeking a reusable, high-flow air intake upgrade. This universal-fit filter addresses a critical bottleneck in stock airflow systems—restrictive paper elements that rob horsepower and throttle response while demanding frequent replacement. K&N's reputation in the performance aftermarket stems from decades of engineering genuine improvements into engine breathing, making this 6-inch-height design a go-to choice for custom intake manifolds, turbo projects, and non-standard intake plenums where OEM filters simply don't fit.

K&N's signature layered cotton-gauze media, treated with a tacky red oil coating, captures airborne contaminants while maintaining significantly lower restriction than paper alternatives—typically improving airflow by 50–70% over factory elements. The 8.75-inch diameter and 6-inch height give this filter broad compatibility across compact and mid-sized engine bays, while the durable plastic top and base ensure reliable performance through aggressive intake pulses and temperature cycling. Unlike disposable filters, the nT series is designed for multiple cleaning cycles using K&N's recharging kit, offsetting long-term ownership costs and waste while maintaining consistent CFM delivery season after season.

Ideal for carbureted restorations, custom intake builds, supercharger installations, and any non-OEM airflow path, this universal filter accommodates a wide range of mounting bracket fabrication and velocity stack combinations. The compact 1.51-pound weight minimizes underhood mass while the symmetrical 8.13-inch width fits tight engine compartments without requiring secondary ducting modifications. Installation typically involves simple bracket adaptation or use of existing rubber grommets; no proprietary clamps or adapters required. Regular maintenance—cleaning every 20,000 to 50,000 miles depending on environment—keeps the filter performing like new, making it a economical long-term investment for serious engine work.