Hopeless Regret

So my buddies 06 with GM Stage 2....Going from a launch you get the standard whine with the intake but then around 4 grand another whistle like noise comes in and overpowers the normal supercharger whine that everyone loves. Also it normally runs about 15-16 psi but now its climbing to almost 20!!! What could this possibly be??? Any Ideas?

braddddddd991

belt slip??idk

RaineMan

Sounds like you are overboosting... the higher the boost goes the more your SC will scream... I wouldn't say it was belt slip... that would cause lower boost if anything.

Your cat may be clogged up... time to take it in and have it checked.

Mikey851

I agree, something is restricting flow.

Red2.4SS/SC

i say clogged cat

Shanman

gm's damn tunes make the car run rich and is cloggin cats up with that bullspit. From underinflation of tires to rich running catyverters cloggin those asses

Red2.4SS/SC

what ??

Shortbus

Cat clogged most likely.

Hopeless Regret

But why would the boost be spiking so high?!?!

InfinityzeN

I'll answer that...

On a Roots (positive displacement) Supercharger, your PSI of boost comes from several factors and is not any indication of how much power your necessarily making. First, you have to remember that it is flowing a set volume of air per engine rpms, which doesn't really change because its volumetric efficiency even at redline stays in the mid 90% range. So there is always the same amount of air per rpm going into the engine while under boost.

Your boost psi is the pressure of the air in your manifold. The psi that it will stabilize at is determined by how much air your engine is flowing and the heat of that pressurized air.

So your manifold is the Air Tank, with the supercharger being the pump moving air into it, and the engine being the pressure release valve. The ratio of pump speed and how far open your pressure release valve are always at the same ration to each other.

When the pump moves air into the tank, it is moving it faster then the valve can release it. This causes it to pressurize. The pressurized air flows out faster than unpressurized air, but still more air is going in than going out. Eventually, with a high enough pressure, the air going in will equal the air going out and the pressure will stabilize. That is at about 15psi for stage two at sea level.

Now, if you do something that increases the heat of the tank or restricts the flow of air out of the valve, the pressure will go higher before it is high enough to make the outflow equal the in.

So ether you have a very bad SC cooling problem (which I doubt) or you have a restriction. The cat going bad is one of the most common restrictions on stage 2 cars.