SR20 Turbo Flutter

[lightsource]

Listen to it.

I recently got my belts switched and now it doesn't squeak, so everything sounds fine but then I got this happening.

tell me what you think...

http://youtube.com/watch?v=vknmcYBNZ-c

[SpeedRacer1]

Sounds like something involving the recirc valve or BOV being too tight and not blowing off enough air. Compressor surge.

[adrianfromthecastle]

yeah, sounds like compressor surge to me.

All that means is that your bov or recirc valve isn't opening up like it should... but nothing to fully stress about

[DrifterProdigy85]

Thats normal. BOV should be held shut if theres no load. Problem becomes if the BOV doesnt open after like 5psi or so.

[Clawhammer]

Last month I started getting compressor surge. After a few days I finally found a boost leak and once I fixed it all was well again. Good luck.

[IanS]

That definitely sounds like compressor surge.

[DrifterProdigy85]

It is surge but its nothing major. Doesnt everyone realize hes just revving his engine. Not even building any boost. The BOV shouldnt open at all with zero boost. It really shouldnt open even with 2-3psi.

[IanS]

The BOV shouldnt open at all with zero boost. It really shouldnt open even with 2-3psi.

Thats not true. A well executed BOV setup will open any time the manifold drops back into vacuum. If at any time there is more pressure in the charge pipes than in the manifold, the BOV should be open. People think the spring is meant to keep the valve closed, when if fact, it is only ment to help return the valve to closed. Pressure diferential, not spring tension, should determine when the valve opens.

This is why recirculation is so beneficial, it allows a soft setting of the valve without adversely effecting driveability. Most people set the valve to tight to keep the engine from stalling and running rich at idle because they want to vent atmospherically. Just listen to any factory recirc valve, do you hear any compressor surge at idle?