Blower Fitting 4in x 3in Threaded

The Blower Fitting 4in x 3in Threaded is a precision transition coupling engineered for air intake, cooling, and forced induction systems where ducting diameter reduction is critical. Built by PARAGON PRO INC, this reducer fitting serves mechanics and fabricators who need reliable diameter transitions in high-flow applications, from supercharger intake manifolds to intercooler piping setups. Whether you're building a custom turbo intake tract or restoring a vintage blower installation, this threaded adapter maintains consistent airflow while accommodating standard SAE sizing.

This fitting features a 4-inch inlet that steps down to a 3-inch outlet, with full NPT threads on both ends for secure, leak-free connections in pressurized systems. The threaded design eliminates reliance on clamps alone, providing mechanical strength under boost pressure and vibration—essential when working with roots blowers, centrifugal superchargers, or turbo applications where air velocity increases after compression. The compact 6 x 4 x 8 inch profile integrates easily into tight engine bays, while the 0.395 lb weight adds negligible mass to intake architecture.

Mechanics fabricating custom boost systems, vintage hot rod restorers, and motorsport builders rely on step-down fittings like this for OEM-quality transitions without the premium price tag. Installation works with both metallic and rubber ducting, and threads accept standard NPT adapters for flexible hose termination. Compatible with fuel-injected LS conversions, LS-swapped classics, and any naturally aspirated or forced-induction platform requiring a 4-to-3 inch diameter step. Verify your ductwork SAE specifications and thread orientation before ordering to ensure seamless integration.