JoeyBalls

Hey guys, while I was drooling over the kit I noticed on the Greddy Type RS Blow Off Valve, on the left it says "Soft", and on the right it Says "Hard" I would imagine this is for the sound effect of the BOV, soft being more of a wwwwwwwoooooppppiiiiiiiiiiiiiiiiiissssssssssssssh, where as the Hard is a quick Laser beam type of noise??????????

Spec_Ops2087

not really, its for adjusting the tension of the spring to help with compressor surge among other things. I guess it could be for sound as well.

JoeyBalls

I knew you would know so what should it be soft or hard?

Envied

It is for the spring stiffness. Softer = less vaccum to actuate the valve; Harder = more vaccum to actuate the valve. So in essence the more boost you are running the harder the spring needs to be set at. In some BOV's you have to just swap out the spring to a different stiffness spring to control it.

parkerdw

Try it out and you will see. I played around with the settings on my RS BOV quite a bit before settling on its current setting. When I first took my car in for tuning, my tuner said my BOV was set so soft it was leaking air at idle. He said you could hear it.

Basically you are trying to set the spring "hard" enough that it activates the BOV when you need it most at WOT but not so hard that you still get audible compressor surge when at partial throttle.

At the softest setting the slightest reduction in throttle causes the trademark bov sound with no surge at all, but you will probably be leaking air through the blow off valve. At its hardest setting you will be getting tons of compressor surge unless you are at WOT at all times but your bov will not be leaking air. You need to strike a proper balance in the setting.

Chris_Lum

set it on the hard side first--you will get compressor surge, then start to loosen it (turn towards soft) until the surge goes away. that's the most basic way to do it.

Spec_Ops2087

That pretty much sums it up

Envied

My question is, how do you recognize compressor surge??

Chris_Lum

I can look stupid and try to spell the sound out to you here, or you can go somewhere like youtube to hear it. You'll get a better idea that way.

Here is a video of the "fluttering" sound that is compressor surge:
http://www.youtube.com/watch?v=MkkA-vfGWg0


Once you have softened the BOV to a point where that is gone, and you have one clean release of air (instead of a fluttering sound), then you should be good.

Envied

Between you and SpecOps, this forum has a lot of great info! Keep it up