vizi0n said:
A single woosh usually means single piston bov, which is used on cars with MAP sensors. The GTI-R came with a MAF sensor instead, so people usually buy twin piston blow-off valve to ensure that there's enough air that is recirculated to the intake manifold for idle combustion or else some very nice backfires will pop out of your exhaust
The whole point of a VTA bov is that no air is recirculated. And, any car that uses a MAF and a VTA bov will get pops and bangs when they lift off the throttle as, the MAF has already metered the air in the intake system, it tells the ecu how much fuel to inject, going by that air measurement but, as the bov has just vented that air out the system, the engine runs rich for a moment. That fuel gets expelled out the exhaust and ignited on the way out, resulting in the pops and bangs !
I thought the idea of a twin piston bov was to let small amounts of charge out with the smaller piston, if you're using part throttle and when you use WOT, both or the bigger piston are used to expel the charge ?!
Now back to the topic !
) It maybe that the spring in the bov is too stiff for the boost you're running ?! You could try a softer one or, if you have an adjustable bov, like a HKS SSQV, just loosen the adjuster bolt and see how it sounds !
And yes, different brands of bov will produce different sounds !
