newbie supercharger noise question

[frank5o]

Did a search, found nothing.

When I floor my car, in say 2nd or 3rd gear, The sound the supercharger makes changes pitch alittle bit. At about 4,000 to 4,500 rpm It almost sounds like something opens up, the sound just changes pitch. I've been watching the boost gage when this happens , and it drops just alittle bit,all the way to red line. The car has 36,000 miles on it and I've had the car two weeks.
The car is completly stock, so I can hear the sound change very well. What is this.

 

[postban]

blower whine? completely normal

check your blower belt for wear. might be why it drops a little

 

[frank5o]

I will cheak the belt, But I was thinking belt slip would not happen the same way every time, like same rpm every time. So the boost bypass valve dosen't do anything under wot? Thats what it sounds like to me, a valve, or somthig is opening up under wot at around 4,000 to 4,500 rpm.

 

[ChicagoMike]

36,000, time for supercharger maintenance. Send the blower to Steigemier, they fully service the blower and make it like new if the snout needs a rebuild. Get it ported while they have it ... MORE POWER!!!!

 

[frank5o]

Ok, so I have to send the supercharger off for maintenace every 30,000 miles........... Any other Ideas.

 

[ChicagoMike]

1. Change the old belt. Belt slip most likely.

2. Change the blower oil.

Ok, so I have to send the supercharger off for maintenace every 30,000 miles........... Any other Ideas.

 

[frank5o]

Change the blower oil? How do I do that? I was under the impression that the supercharger uses the crank case oil.

I've been doing some reading on the boost bypass valve, I think it might be bleeding off boost becuse the motor is getting to hot, just an Idea.

 

[ChicagoMike]

The oil is self-contained in the snout of the blower:

how to change your blower oil:

http://www.svtperformance.com/forums/showthread.php?t=146570&highlight=change+oil

also the snout/rotors sometimes need a rebuild depending on how much boost the pulley has been spinning ... does it have an aftermarket pulley size? Again, steig specializes in rebuilding our snouts/rotors within the blower.

Change the blower oil? How do I do that? I was under the impression that the supercharger uses the crank case oil.

I've been doing some reading on the boost bypass valve, I think it might be bleeding off boost becuse the motor is getting to hot, just an Idea.

 

[Silver03]

Did a search, found nothing.

When I floor my car, in say 2nd or 3rd gear, The sound the supercharger makes changes pitch alittle bit. At about 4,000 to 4,500 rpm It almost sounds like something opens up, the sound just changes pitch. I've been watching the boost gage when this happens , and it drops just alittle bit,all the way to red line. The car has 36,000 miles on it and I've had the car two weeks.
The car is completly stock, so I can hear the sound change very well. What is this.

I know what sound you are talking about...mine does it too. I was thinking boost bypass as well, definitely not something that maintenace is needed for since mine has done it from day one with 5 miles on it...

 

[frank5o]

Thanks for the info ChicagoMike

Once agian my car is completly stock, so I'm not sure if a rebuild or changing the oil is in order, I will keep it in mind though.