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BOV question!


Well-known member
Jun 19, 2011
So 313 came with a Garage Modded BOV right..

So what Im reading about this mod is that it allows you to choose from fast mode or slow mode?
Whats the difference between the two? Which one would be more suited for 16 psi?

Right now on the 2nd nippled towards the bottom of the BOV, its hooked to a boost source and the BOV works a regular PSHHH sound.

But when I disconnect the boost line to this nipple, plug up that boost source, I believe I get whats called BOV flutter, where it makes a PSHH and a slowly degrading chatter sound. Is this bad?? I've been searching all over the internet and getting mixed descriptions on this Flutter subject.

I know that if you get flutter under WOT, it is extremely bad, and I read that if you get a degrading pitched flutter off throttle, its the BOV opening and closing like a bouncing ball..

I guess this is kind of a 2 question thread lolol.. but I want to know the truth about BOV flutter and this slow/fast mode garage mod thing.


Well-known member
May 5, 2006
Burnsville, MN
Well there's "flutter" and then theres copmressor surge. Sorry I can't really explain further since I don't know the specifics.


Well-known member
Dec 9, 2007
In a van down by the river, Iowa
559 has a Garage Mod BOV, the flutter you could be hearing is the spring/piston actuating inside the diaphragm.

He doesn't get compressor surge.


Well-known member
Feb 12, 2003
Danville, Pennsylvania
The vacuum lines should be hooked up to a ingersoll rand Pressure Switching Solenoid which switches by itself between high and low boots by switching where it gets vacuum from by how much boost it sees. Or something like that.

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