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I found this on the silicone intakes site, while I was surfing around looking for some bends to make up some new IC piping, worth a read :

BOV
 
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He's missing the granddaddy of all BOV myths: That the BOV is the primary boost control device.
people think the BOV is a boost controller?
 

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i'd be rude enough to laugh in someone's face if i saw that. haha.

one thing misleading on the site....it says "pressure doesnt keep the valve closed"

thats true and false.

on some BOVs (diverter valves) that are open at idle, the lower the vacuum and closer to positive pressure, the further sealed/closed the valve is. while the higher the boost doesnt mean the more "closed" it is, boost definitely does close the valve.
 

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I didnt find anywhere on the site about it saying pressure doesnt keep the valve closed.

Maybe you are confusing them saying that the spring is to keep it closed under idle or decel type conditions and not solely rely on vacuum pressure to keep it closed. And they mention if you have a diverter/recirculatiing bov it doesnt matter.

Here is where they mention it- directly taken from the site:

Rather, the purpose of the spring in a BOV is to hold the BOV closed when your throttle plate is closed, IE during idle and deceleration conditions. Under these conditions, the vacuum in your intake manifold is much higher than the vacuum in your intake piping (therefore under the BOV piston) so the BOV has a natural tendency to spring open. Being open isn't even a problem if you are recirculating your BOV into your intake, however if you are NOT recirculating, it can allow unfiltered air into your intake which IS a problem.

Therefore, your goal when selecting a BOV spring and adjusting the BOV should NOT be to select a spring based on your boost level; that makes no sense. Your goal is to get the BOV to stay CLOSED during high intake manifold vacuum/closed throttle plate conditions, using the very smallest amount of spring energy possible. Using less spring energy will allow the BOV to snap open as rapidly as possible when pressure release is necessary.

And to add to your comment on the boost controller- people might think since it basically controls boost (as it releases all boost) they think it controls it. For those people- I usually whip out my pocket dictionary and show them the definition of control.

But its like how some people expect bolt-ons to make a Honda fast.
 

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yeah it was a misinterpretation on my part.


clicking on links at 2am pwns me
 

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All BOVs have a reference line coming into the top of the BOV from your post-throttle body intake manifold. Under high boost, the force holding the BOV closed is BOOST! The pressure coming through the reference line is equal to the pressure under the BOV piston. Therefore a VERY mild spring will hold it shut just fine under these conditions.
This is not true of OEM valves. A naive investigator may see this and go "yeah, thats how it works" but someone with their eyes open will notice that there is a pressure feed to the back side of the diaphragm too such that under boost it is ONLY the spring holding it closed.

I'll be doing some BOV modding/experimentation when I get home as my OEM GTR valves won't be enjoying 27psi (read will leak). There are various solutions, but the only one I'll be happy with is a stiffer spring and otherwise stock setup.

I don't have time to explain, but read up on the DSM valve mods for more info. It's not a good solution overall, but it does stop the leaking.

Fred.
 

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you have an external wastegate??

Most people I know usually say wow, hear how loud his wastegate is? or I love the sound of the wastegate going PSHHHHH.......

yea???
Yea itz mostly people that dont know too much about turbos n shit. it jus mad shiny n stands i guess thatz why
 
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