Technical Are all roots (GMC type) blowers noisy ?

Do all the roots type blowers make that high pitched whining noise? I have heard that its because of the straight cut gears........and that angle cut gears make the noise go away. Then I heard that the gilmer belt also created the noise too...........then I heard that drilling holes in the pulleys alleviated the noise from the belt.
An inquiring mind wants to know...........whats the real truth?

 

I have an old v belt setup on my 32. Its not very loud at all. Of course, the exhaust is so loud that you would never know.

 

Gears driving the rotors are fairly noisy.
Just like a quick change.
Have both for beautiful music.
And Solid lifter cams
And open headers

 

And M-22 Muncies too!

 

The belts can be noisy. I'm not sure if holes in the pulleys make any difference, though. They still whine.

 

Blower whine gives me goosebumps....
and sweaty palms, too.
sweet music....

 

I've known guys who wanted all that racket and then added a gear drive to make sure folks heard them coming.
More years than I want to count ago there was a discussion going around about drilling the pulleys to reduce the noise from the drive belts.

 

Not sure how effective it was but it was thought that it lets out the trapped air from between the belt and pulley.

 

Toothed belts make more noise than v belts

 

Yes, roots blowers are noisy....what's not to like?!

 

I don't find mine to be that noisy but the quick change pretty much drowns everything else out.

 

It's time to dispel an untruth. Every gmc style blower I have disassembled has angle cut gears. That's part of how you set the rotor to rotor clearance. Most of what you hear won't be there until it's under boost. That's when the "magic" occurs.

 

It’s a good noise…..

 

Mine isn't to bad,,,, Most of the noise comes from the belt.... But what's not to like....

 

I’m with WFO guy,,,,,I’ve never seen a straight cut drive gear in a GMC blower .
The helix of the gears is what allows the rotors to time,,,,,( to give clearance ),,,,,between each rotor .
The rotors never touch,,,if they do,,,,they fail .

Yes,,,,,some gears are louder than others,,,,,,,some are miserable to listen to,,,,nerve racking after a while ,,, And some are very pleasant,,,,not too obnoxious.

I always polish the teeth in my assemblies,,,,,,just to give a smooth surface,,,,,,and use good 90 wt. gear oil,,,,the real stuff,,,not synthetic .

Tommy

 

Majordy of Noise is air trapped between 1/2 , 8 , 14 belt & pulleys