Blower/Supercharger whine

[Mekanic]

Hello all. Just found these forums. They are great!!

Need alittle help resolving a friendly disagreement I'm having with someone. It centers around this clip: http://www.rapperdmx.com/jeramie/JeramiesDynoRun1.mpg

What produces the high pitch whine? The increasing air flow or is it the blower itself ( bearing/belt/pulley )?

Any help would be greatly appreciated

[gttouring]

I thought it was a combination of both.
A turbo car does make a slight sucking whine at speed and WOT, and a super charger gears and belts and (unmuffled turbine sound as no exhaust pulses go through the housing to dampen it) some spinning sound. One answer as we have seen is never correct, I will stick to my guns as a combo of events-gears, spnning wheels, pulleys, and rushing air and remember why I mentioned a turbo would be quieter.

[gttouring]

after watching it I will say 'that car sounds like an animal what were the numbers?'
The supercharger whine is so loud! very likely you can hear the throttle and engine speed directly related to speed and pitch of the blower, the Thunderbird uses a Roots type doesn't it? these are much noisier i bleieve than the turbine type blower I was thinking of, but yes the sound is related to the spinning gears and air sucked and squished through. blow through a pinwheel thing and you can hear it sort of, the air through you mouth across your lips and through the wheel, the wheel itself makes noise as it spins, and your air does too.

[graham bahr]

i'm not sure if this applicable to all supercharged cars but 1930's mercs used to really scream when the blower was engaged and apparently the noise was created by air being blown through the carbs in a similar manor to which a wind instrument makes noise by blowing air across a reed or opening.

[Mekanic]

Thanks guys.

gttouring- I don't know what the numbers were for that vehicle.

The point I was trying to make in our "disagreement" was that unless the blower was intentionally setup to make that loud of a whine that there is probably something ( gear/belt/bearing/rotor ) going bad.

I have been to alot of NHRA races and I have never heard any blower sound like that. I have a '98 Grand Prix GTP Coupe with a blower. At 6000 rpm you can't tell it's there by sound.

I am a professional diesel mechanic. The only time I've ever heard a 671 that had whine like that was when one of the rotors was shot.

[Monaro]

I have 2 supercharges mounted on a Lexus V8 in a open wheeler which are driven by belts.At 15pound boost they are quiet and no whine.Must be gear driven as V8's fitted with gear drives sound similar.

[norman-normal]

The construction of a siren is much the same as a turbocharger or centrifical supercharger, but not a 'roots' type.

A turbo will turn well over 100,000. RPM. It will be heard!

[KC]

In drag racing, the whine and gulping sound of the blower (supercharger) is easily heard at idle. Top Alcohol engines sound flat wierd as they idle. The engine thumps then pauses and the blower whines and takes a huge gulp of air and then the cycle starts over. The process takes abotu 1 second per cycle. The engine lope is severe to say the least. However, the throttle response is awesome especially whne coupled to a super high flow fuel injector like an Enderle.

We use an Enderle on a unblown 540 cu. in. BB Chevy and the throttle response is like a light switch. From idle to redline at the flick of your hand on the throttle.

[Bruce302]

I offer this only from what I have read: The blower whine is the air trapped between the toothed belt and the blower drive cogs.
Supposedly if you drill a small hole through each tooth of the cog it won't make the whine. That coinsides with Monaro's engine, but again there is the gear whine factor, DD (Roots) blowers are gear connected.
Bruce.

[boyracer]

I'd agree with the last comment, most of the whine of a supercharger would appear to come from the belt. The noise of a gilmer drive pulley (toothed pulley) on an unblown car is very SIMILAR to that of a blown car. Not saying it accounts for everything.