[71gtx]

I've really been trying to figure out what superchargers whine or what makes them whine. A lot of videos say they have the same style (say a weiand 6-71 or 8-71), but some whine and some don't. Some whine loud some whine soft, some whine annoyingly loud, etc.

Such as these:

NO WHINE:
http://youtube.com/watch?v=84LcOzIs8go

DEEP WHINE:
http://youtube.com/watch?v=NLvj8D_DVeE

NICE WHINE:
http://youtube.com/watch?v=b-yaFNu6oU0

It can't be certain models since some are the same but have different sounds. Why is this?

[XNTRCI-T]

The whine is caused by the cogged (Gilmer) belt drive. You can make it louder or softer by how tight you make the idler pulley. However, the tighter you make it, the more you risk damaging the bearings in the blower and the front main bearing of the motor. Some of the smaller blowers use v-belts or serpentine belts, and they don't whine.

[n-gin]

The difference is iin the belt. also sometimes the placement of the idler/tensioner on the belt.

A question to ask is why vortec superchargers whine and they use a serpenine belt(smooth).

[XNTRCI-T]

I would guess that centrifugal superchargers like the Vortec whine because of the high RPM of the compressor turbine, just like a jet engine. Turbochargers whine for the same reason, I would guess.

Also, on the Gilmer drives, the tone of the whine is different for an 8mm versus a 1/2" belt. The 8mm has a slightly higher tone than the 1/2". (I'm using the word "tone" instead of the proper term "pitch" to avoid confusion with the pitch of the belt, which is the spacing between cogs).

[ericnova72]

XNTRCI-T is correct, it is the air being squeezed out of the pulley teeth by the belt. Same reason treaded tires squeal(and 4x4 tires howl) when you spin them and drag slicks don't, air being pinched through the tread grooves where the tire meets the road.

[thefloyd1973]

It depends on the size of the pulley. the smaller the pulley the more it will wine because of it creating more boost.

[XNTRCI-T]

Originally Posted by ericnova72

...it is the air being squeezed out of the pulley teeth by the belt...

Actually I think it is the meshing of the cogs on the belt with the drive pullies that makes the noise. Sort of like the gear noise you hear in a transmission with straight-cut gears (ala the beloved "Rockcrusher"). I know there is some wear going on between the belt and pullies, because I get a layer of fine rubber dust all over my polished water pump between washings.

Here is where my "blower expertise" comes from...

[71gtx]

Originally Posted by XNTRCI-T

You can make it louder or softer by how tight you make the idler pulley. However, the tighter you make it, the more you risk damaging the bearings in the blower and the front main bearing of the motor.

Wow, that's quite interesting. I would have thought it was more in depth that just relating to the belt and pulley system. So in essence, I could put any 6-71/8-71 system on a motor. When I start it and have a quiet blower, I can just adjust the tension in the belt and it will get louder and louder?

And when you say that the tighter you make it (the louder it would get), the more risk for damaging bearings. So are guys naturally damaging their blowers just for that whine, or is a certain amount of tension and whine acceptable within specs?

By the way, nice paint job XNTRCI-T, never seen that before!

[ericnova72]

XNTRIC-T, I'm just repeating what I was told by tech at Blower Drive Service
(BDS) and it's basically word for word. The faster you spin it and the tighter the belt the more forcefully you are expelling the air, therefore the screech gets louder. You're right, belt pitch does affect this, the 1/2" pitch square tooth belt is louder than the 8mm rounded tooth. I was told if I wanted to lessen the whine to drill 1/16" holes in the grooves of the pulleys similar to the pattern on a cross-drilled brake rotor, this will allow more escape paths for the air. Some parts in automatic trannys are drilled the same way for fluid to escape, but for cooling reasons not noise.

Edit: The Vortech and similar blowers whine because there is a step-up gear drive inside them of around 4 to 1. There is one that is silent(Powerdyne, but I might have the name wrong) that has an internal wet belt step-up drive, and Paxton was using a planetary type ball drive at one time. These types are basically belt driven turbos and need 20,000+RPM to make boost.

[Stroke]

the tighter you make it, the more you risk damaging the bearings in the blower and the front main bearing of the motor

When you spend the big bucks on a blower motor you should at least consider the following. Expensive? Yes. Worth it? It's your motor, it's your money, you decide.

RCD Engineering has...

Gear Drives with Bearing Support & Crank Trigger

A complete gear drive and integrated crank support bearing assembly. In addition to all the features of our standard gear drive, this gear drive has a high load capacity roller bearing housed in the front cover to support the nose of the crankshaft from the stress placed on the crank by the blower belt.

[Blazin72]

I have a little 142 Weiand and it has a serpentine style belt. It also whines. I always figured it was the straight cut gears meshing with with each other as they spin. (?) You know, much the same as a camshaft gear drive whines.

[71gtx]

So what would be a good price estimate to build a supercharged forged crank/piston small block chevy or mopar engine? Don't want to break my bank, this won't happen for a while, but my gosh how I love them superchargers.

[dawg]

the whine is caused by air getting under the belt.
tighter you go the more whine you get.
I played with my belt drive quite a bit.
my camaro does it:

my 53 does it even louder:

[n-gin]

Straight mess gears(spure gears), and air getting trapped under the belt will make a whine. The rock crusher (M22)trans had a whine to it due to the spure cut gears. Spure cut gears are stronger than angled(worm cut) gears. Worm gears are quiet but due to the worm style of cut, the gears are forced with a side load pushing out on the casing.

As for the tension yes that will make it louder. Though I dont believe the poeple with the superchargers or blower will sacrafice bearings to get a louder sound.
It just the nature of the beast to whine cause of the belt.
As far as the serpentine system making a whine there are spure cut gears in the housing to turn the other "rotor" or whatever the name is. That is were it is getting the whine from.

[n-gin]

Dawg,
Were can I get one that belt systems you have. It looks way cool