But it's there all the time off throttle.

 

So I'm building my CTSC setup now, and I want a nice blow off sound as well on my after-cooled setup. Rumor has it that while running low boost wont engage the spring in the BOV well enough to release enough pressure.

How many lbs of boost on a SC should you run b4 you consider using a BOV?
It appears that there are a bunch of people running these, but are they really doing the job? I love the sound they produce, but I car a "little" about function too.



Mike

 

read my post above.

you wont hear a bov under probably 8psi or so, but you still NEED one regardless of your max pressure.

 

If all you want it for is the sound just be honest with yourself and get one of these:

Night Pager

 

Form and function pal form and function.
Question answered sort of... what about spring tension on the release valve on a low pressure system=lower lbs of boost?

 

could work a little bit but not much. i'm not so sure that the cause for such low volumes is a result of low boost pressure. i mean many turbo people run 7 or 8psi and still get their big nasty blow off sounds without any fuss.

i think it has to do with the fact that even though the valve is told to open when the manifold sees vacuum, the blower itself is still spinning. although it's turning slower than when under load, the blower has to slow down along with the engine on decel, not just freely by itself. i think as a result this will regulate air flow to the valve in some sense, and keep volumes down.

also, keep in mind that centrifugal blowers slowly raise pressure over the powerband - not within a fraction of a second like with turbo setups. due to this slow rise in pressure, it might be safe to say that even though the manifold might be seeing 5psi, the same pressure may not be apparent throughout the entire system beforehand.

i'm not entirely sure, but i have had 3 centrifugal blowers and 3 turbochargers on my car - all at different boost levels. the blowers have been consistently lower in volume and the actual air flowing out of the valves when released have been at a lower pressure over a longer release than with the turbo setups.

utilizing a weaker spring might allow air to escape the valves more easily, but i dont think that will help much in terms of volume because of the deceleration properties of a centrifugal blower. to add insult to injury, using a weaker spring could leak boost at high pressure levels, and would obviously cause a loss of power.

i can't believe this thread has gone on for so long. some people are just determined to make all the right noises - i only hope you guys are concerned for making as much power as possible too!

 

Power is a major part of my concern, and not having the returned pressure kick back to the blower working against its operational direction. I have to admit, the sound is just a bonus for me and I WANT IT!

Thanks for your input guys. I'll do a little bit more reading up on this B4 buying a BOV, plus I want to be in the 10-12lb range prior to adding a BOV.

 

[QUOTE=mjschrage,Aug 12 2009, 11:49 PM] Power is a major part of my concern, and not having the returned pressure kick back to the blower working against its operational direction.

 

Even with the Godzilla? My old car.[media]http://www.youtube.com/watch?v=B1PJvCVOL5Q [/media]

 

I'm glad you live close by!!!