i have a p reg wrx ......the std dv is on the pass side just off the ic on a short black pipe i tryed an old recirc valve i had it work but the car didnt tik over sum one said i need a twin piston dv it it true ?

 

HKS super sqv is on mine and it sounds the muts nut, my mates got a baily twin piston i think and it sounds like its passin wind compared to mine cant go wrong

 

thaks m8 but do i defiantly need a twin dv

 

I have heard people saying that you do and when I went and got mine they highly recomended it so thats about al I know if you try doin doin a search on here youl find somet and its quiker than waitin for replys sory i cant be more help

 

Whats wrong with the standard subaru dv? The standard dv is a recirculating item. Sorry if I didn't quite understand the question, I must learn to not punctuate my posts aswell!

 

Blow Off Valve - HKS Super Sequential Ever wonder why rally cars make that sound you hear when you open a bottle of pop? Well, maybe not exactly like that but more or less similar to the sound of air being released (air, not gas!). You usually hear this when you let off the throttle, sorta sounds like a woosh!. In effect, what you are hearing is the sound of built up boost pressure being released from the intake system. The reason for this is that the turbocharger will keep spinning even after you let off the gas. So as you close the throttle plate, allot of pressure builds up in the intake system. This becomes problematic in that this excess pressure can cause the turbines to seize. Ultimately, this would destroy the turbo unit. For this reason, we incorporate BOV's, bypass or diverter valves. These mechanism work because on the other side of the throttle plate, vacuum gets built up in the intake manifold. Blow off valves, diverter and bypass valves all work by detecting this vacuum. Having done so, they use this vacuum to mechanically open a valve in order to relieve unnecessary boost from the other side of the throttle plate.

Forge Diverter/Dump Valve Now let us differentiate BOV's, diverter and bypass valves. First, a blow off valve (seen top right) is common to high performance applications in that it provides the least bit of compromise. A BOV essentially releases this pressure straight out into the atmosphere. Quite often you will find that these units take on particular shapes, making them resemble musical instruments. I guess some people out there really like to flaunt their gadgets. Just wait ti'll you see how much they impress the ol' 5-0. Aside from this legal dilemma, the second problem you encounter with BOV's is that the mass air flow sensor will cause the engine management system to "think" that the air will go into the engine and in turn will release an appropriate amount of fuel for it. However, a BOV system will vent this air out before it gets to the injectors causing your mixture to run lean. In turn, this will result in unburned fuel to escape into the exhaust system. This is why you often see flames and hear those "pop's" in rally cars. It is unburned fuel exploding in the exhaust system. Doesn't take a genius to figure out that this is not the smartest application for the day to day car. For this reason, reasonable tuners will usually employ a bypass or a diverter valve (see left). These units essentially redirect this pressure back behind the compressor causing the net flow of air to remain constant. This in turn slows the turbine down gradually and allows the air flow sensor to work appropriately.

 

Yea, but you still know that a vta is on the cards, innit!
Only kidding, whatever floats your boat, thats what I say!