Air Leakage Ports:
The two oval slots on the output plate are air leakage ports. Their only purpose is to decrease operational noise from the blower. Arnie, from Eaton Corp., explains their function like this, "When you stomp on the gas, the boost shoots up and the air flow goes supersonic. The air then slams back into the output plate and through the leakage slots, which reduces the hammering of the air into the housing causing less noise. The OEM can not have such loud NVH, that’s why we put them in the housing. The 2 small ports are not there to feed air, only to reduce noise." Basically, for the best flow and most efficiency, these ports can be blocked off, making the outlet port (triangle slot) the only port on the outlet plate of the housing. Closing these ports will not increase IAT's; however, it will make the supercharger much louder when in boost. As an example, aftermarket supercharger companies, such as Harrop, Roush and Magnuson do not use these slots in their blowers. It should be re-stated, that you should consult professionals regarding closing these ports; and do not, for any reason, plug them with JB Weld. Improper closure could eventually lead to pieces coming apart and loose debris destroying the rotors and housing. Opening up these ports will only have a negative effect on efficiency. Do not port them.
So has anyone done this? I am going to do it, but would like to hear some feedback, I have stage 2 and a CAI and want to make the whine even louder.
Thoughts, suggestions, pictures?
Information taken from