What it says in the title.
is it the charger itself or is it the noise of the S/C coming through the intake?

Just curious because since i have a cone filter on my GTP i can hear the whine much better. its not as loud as the vortech in the Camaro...

Pat

 

I believe it has to do with the bearings. That's what I was told by a guy at my local dyno shop anyway.

 

Some of it is the snychro gears in the blower that keep the 2 rotors properly aligned and prevent them from crahing into eachother and chewing themselves up. This noise stays relatively constant in volume, although it increases in pitch as revs increase. It's a rather high-pitched, "gear whine" kinda noise.

The other part of it is caused by the sound waves generated in the intake from the air being basically "ripped" by the fast-spinning lobes. This is a noise that gets louder with more throttle, as well as increasing in pitch with RPMs, but is not as high pitched as the synchor gear noise. Why? The throttle plate itself acts as a sound-deadener. When you're at idle, very little noise can pass through the intake past the nearly-closed throttle plate. At WOT it has an unrestricted path back through the intake, throttle, air intake system, etc. An open element filter will allow this noise to radiate directly into the engine compartment through the air filter. The factory air intake system is much more "closed" and is also tuned specifically to eliminate some of this noise, so going to an open element will be considerably louder under all conditions (but flow better and make more power).

 

its mostly just the gears. notice with a roots blower you can be cruising with the throttle open and not hear anything.

step on it until you get to 1PSI and you begin to hear the noise. thats the belt pulling the rotors, instead of just spinning them.


the blower is always spinning, but until it begins to take in more air from the throttle body than the engine can handle, it doesnt do anything except free-wheel like a windmill. even though the belt is spinning the thing, its basically spinning itself.

when you open the throttle enough to let the blower grab air it begins to meet resistance of the motor not wanting to take in the air. this causes the gears in the case to finnaly mesh instead of "float" and they begin to whine... there are no synchros that i know of in a roots blower, but one with a transmission like the procharger who knows....