309VS EC Velocity Stack uses a radius that helps guide air to increase velocity and flow. 

EC designed the first “infinite” radius venturi for Tillotson Carburetors and later adapted by other manufacturers. This improved the airflow and signal of those carburetors. Our air inlet velocity stacks complement those designs to provide the best airflow potential from those carburetors. 

We recommended using velocity stacks over plain filter adapters in every class that they are legal to use it. Check your rule book before ordering. Each piece is CNC machined from 6061-T6 Aluminum and includes all parts needed to install.

Fits Tillotson HR-181, HR-191, HR-196, and many other HR Models (Approximate 2.625” OD x 1.450” ID, 3 bolt spacing 1.8125” fitted 1/4-20; check your air filter for fitment.)

NOTE: Use AFR90 or AFR146 Air Filters for the Best fitment.