DIFFUSERS

In order to attain uniform airflow distribution in a duct, the minimum radius that a duct or tube can be bent is about 1.5 to 2.0 times the diameter of the duct. For a 4-inch diameter duct feeding a 4150 style throttle body this yields a 6-in bend radius. The end result is that the absolute shortest a 900 inlet should be is about 6-in (ignoring the fact that a single 4-in duct does not line up well with a 4150’s venturi spacing). Anything less will result in the venturis closest to the inlet of the duct getting significantly less airflow than those furthest, due to separation of air from the short side radius of the duct.

The CAS Diffuser is a 1 into 4 low profile inlet air duct designed to provide uniform cylinder – cylinder air distribution on fuel injected engines using 4150 Holley style throttle bodies. Units are available with or w/o integral 3 bar BOSCH TMAP. Uniform flow venturi to venturi (and within each venturi) is attained due to the smaller bend radii required of each individual tube or runner.

Note: Usage of these units on carbureted engines significantly affects the air/fuel ratio of the secondary venturies.

Part Number(s):
DF-350-45 (3.5-in inlet, 1.75-in runners, 450 orientation, includes mounting hardware)
DF-350-45B (3,5-in inlet, 1.75-in runners, 450 orientation, includes mounting hardware & TMAP)
DF-350-90 (3.5-in inlet, 1.75-in runners, 900 orientation, includes mounting hardware)
DF-350-90B (3.5-in inlet, 1.75-in runners, 900 orientation, includes mounting hardware & TMAP)
DF-400-45 (4.0-in inlet, 2.00-in runners, 450 orientation, includes mounting hardware)
DF-400-45B (4.0-in inlet, 2.00-in runners, 450 orientation, includes mounting hardware & TMAP)
DF-400-90 (4.0-in inlet, 2.00-in runners, 900 orientation, includes mounting hardware)
DF-400-90B (4.0-in inlet, 2.00-in runners, 900 orientation, includes mounting hardware & TMAP)