Is your blow off valve partially open at idle?

[makriluc]

Mine is at idle under 20 hg of vacuum.

 

[96S/Cobra]

Yup

 

[Helomech74]

SC or Turbo setup?

 

[makriluc]

Sc p1sc

 

[stangbanger856]

yes that is normal. I have a Vortech race BPV and will stay open till 14lbs of vac, anything less then that and it shuts.

 

[makriluc]

Thanks guys for your reply.
For those who may be following my threads, I'm trying to solve mutiple problems after installing a previously owned P1SC. First I had STFT problems. This seems to be solved now, I had a bad fuel injector. Now my tuner can't go any further because of my MAF reading (a graph that looks like a 9 on a Richter scale). According to him it may be a bad BOV. But it's brand new. Now I just noticed that my PMAS may have been installed croocked.

 

[SVTContique]

BOV should always be open, as soon as you put enough load on it shuts closed and thats how you see boost. Otherwise you would be in boost everywhere you drove (SC creates boost at every RPM range).

 

[makriluc]

Khameleon, should it be fully open at idle?

 

[Helomech74]

Khameleon, should it be fully open at idle?

Yes, on a centri application it will be fully open at idle if adjusted properly.

 

[makriluc]

Ok then.
Mine isn't. According to my tuner, my internal spring must be too strong. It's only one third open and is adjusted as soft as possible. I will either have to change the internal spring for a weaker one or completely change the BOV itself.
Any recomendation on a new BOV?

 

[Helomech74]

I run the Procharger big red on my street car and it works great. I've also used the Tial Q with the SC spring and it works just as well.

 

[Tunedprt91]

I would just get a softer spring. I have a tial q on my car with the supercharger spring.

 

[makriluc]

After looking and listening (you tube) to different BOV, I'll be going with the Tial Q.
After Helomech & Tunedprt's comments, I read different articles on BOVs and found out that there is a difference in BOV between turbo application and supercharged application, mainly in the spring tension.

 

[Helomech74]

Yeah, a lot of folks think that a BOV on a centri application is supposed to work like a turbo and they don't. It will be open during idle and most all steady state cruising. When you hit the throttle the valve starts to close (mine is closed at around 0-3 in/HG) and opens again when you let off the throttle. It has to stay open during no load situations so you're not constantly building boost.

The Tial Q will work great (just make sure to get the SC spring for it.)

 

[flowgoode]

I read different articles on BOVs and found out that there is a difference in BOV between turbo application and supercharged application, mainly in the spring tension.

The way a blow off valve works, is the same way a bypass valve works. They are one in the same for the most part.

I use a Vortech Mondo valve.

On turbo applications, the valve doesn't have to be open as much during idle/no load because the turbo is not forcing air into the motor. The turbo needs to spin much faster to start getting boost into the pipes/engine.

On a supercharger application, the valve should be open more because the air is getting forced into the engine even at idle because the supercharger is already spinning fast enough to create boost. So when you're at idle/no load, the forced air needs to go somewhere, so it goes out the bypass valve. So when you need the boost, you press the gas, the motor vacuum goes to 0, and starts going into boost, and closes the valve to hold the boost in the pipes/engine.

 

[Tunedprt91]

Yea like others have said it opens and closes depending on throttle. Here is a vid of mine with some normal driving. You can hear it open and close when I shift or let off the gas.

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