ptkthekid

Bump for more opinions

blackS197

Depends for what car. For the S197, loudest to quiet in order. I have been in cars with all these SC's

1: Roush/Whipple: Roush is a deeper whine where as the whipple is a higher pitched.
2:Saleen: Higher pitched than the above not as loud.
3: Kenne Bell: Super quiet. Not sure about 8 psi and over.

The more you boost the louder the whine.

boss_dude_429

hang on foxgt the reason that roots are louder than everything else is because of the belt, the tighter it is the less "whine" the looser the more. and the fact that a 71 series charger is OUTSIDE the car is a factor too

ESG-642T

KB: WOT
vortech v1: idle / cruise

FoxGT

The twin screw & roots use the same snout design. Belt tension will have nothing to do with sound unless you have a bad bearing or bad coupler.
If you're talking about sound coming from the front of the supercharger, you can't catagorize the roots & twin screw based on this because of companies design. Eatons use a straight cut gear on their forward & reverse drive gears, KB uses helical cut gears, i'm not sure what every brand uses.
Size of the supercharger, pressure ratio, case design, rotor design, & speed all effect sound.

A majority of the sound from the 71 series comes from the design, not from it being outside the car (if your hood isn't tall enough) Some can be loud even with the hood closed. Take the roots s/c'd vette in this vid for example:
http://www.youtube.com/watch?v=gSxOb-V_jww
And keep in mind you can hear it over all of the other cars that are at wot. Sound slits still open on that too.

centrifugals are louder at idle/cruise because they're compressing more air then. The roots & twin screw don't make as much sound because there is not much air for them to use. If you were to take a roots or twin screw & move the throttle body to after the supercharger then it would make quite a bit of noise, but unfortunately your engine wouldn't be lasting too long if that were to happen.

67 evil eleanor

Just stumbled on this thread, anyway, mine wines, and its only an M112. The car is 41 years old though. Turbos are comming.
http://www.youtube.com/watch?v=DkHvzET5I-o