Supercharger porting tips...

FrankenBird

Registered User
my engines getting rebuilt and I have a mp supercharger, it already has some slight porting on the inlet side where it connects to the plenum and the tabs on the top have been ground down..
what I'm wondering is this: are the 2 ports on either side on the V on the top of the supercharger ( where the hat goes) are those silencing ports? my mechanic mentioned to me that if I want some extra boost from my sc I should weld those ports shut and open the V up a few mm's...is this true? I have seen a sc on craigslist that had those 2 ports welded shut but thought that it would hurt flow since ur closing off inlets..
can I weld shut those ports and leave the V alone and just have the sc sound louder? or will that hurt performance? should I weld the ports shut and open the V up like I was told? or should I just leave it alone?
its a mp supercharger with a mp plenum and my setup will have a 7% pulley on the sc, 75mm Tbody,42lb injectors,3in intake, 73mm mafs and stock exhaust but hollowed out cats..
anyone done this befor?.......
 
Filling the ports simply makes the blower whine louder ...as for increase in boost it's minimal. The MP Blower should flow rather well as it designed.

-Tim
 
You aren't going to get far with just hollowed out cats, I would atleast replace the stock resonator and more since you are adding all this extra air and fuel you need it to leave the car even better to prevent your HG's from popping.
 
The two holes are silencers, yes. I've Googled this into oblivion as to others' results, and the consensus seems to be that it's not worth it to try to fill them. I remember seeing somewhere from an official Eaton statement that it would add .5 of a psi or something like that. The problem with filling them, is that if you weld them, the case will likely warp, and even if it doesn't, you still have to make sure that the welds don't touch the rotors. If you use JB Weld (which is not advised), you run the risk of the material breaking loose, and the best case scenario is that it ends up in your intercooler. The worst case scenario is that it somehow falls back into the supercharger after having ricocheted off of the supercharger top/ hat.

You can open up the V quite wide. Just make sure that the V matches the rotor edges.
 
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Are the factory cats that bad? The driver's side one looks like it would be terrible for flow.......I'm lucky. When I got my SC, it had the cats removed by the guy that I bought it off of, and anything before 95/96 around here doesn't require cats.
 
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