BOV to atmosphere instead of powerpipe.....ok?

Cobra912 said:

thanks 85 for the pics. that's neat you tried something different. Can I ask...where did you hook up that blue hose to? I sound like such a dummy but is that the vaccuum hose? And is that what effectively causes the bypass to open? I have so much to learn about blowers.

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It just hooks into the vacuum tree...anywhere that gets good vacuum.

strtrcr50 said:

85_SS, is that a mass air car? I don't know much about 4cyl turbos and even less about merkurs. If it were speed density, it wouldn't matter. But with a mass air car, it is not good to dump metered air.

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Not mass air, but similar. They use what's called a vane air meter, which has a door that opens and closes sort of like a pre-throttle body..pretty weird. The thing about dumping metered air is that for that split second that the valve dumps air when you're off throttle, the only problem you get is a split second of running rich (since you've just lost air that the engine would have got and the ECU has already mapped out the fuel flow to match it). So as far as causing damage, that won't happen...because the exact same thing happens with a blowoff valve. When you're routing a bypass valve you want the return to go back down before the power adder (blower or turbo) but AFTER the mass air/VAM unless you're running speed density or some other fuel management that doens't have an air meter. This way the air that got metered stays in the intake track but doesn't surge back and potentially damage impellers, but doesn't get re-metered or released to atmosphere.

So in short...either one is fine. To say one is better than the other is sort of splitting hairs. Yeah, a blowoff valve technically causes a split second rich condition, but that's not really a big deal. A bypass valve prevents this, and the idea is that since the air stays in the intake track that spool up time is shortened but this is also splitting hairs. And, as far as my car goes, with the Bosch BPV i'm using it's actually pretty loud when it opens up at 16psi. You can hear it from outside the car just like a BOV but not quite as loud.

fiveohwblow said:

I loved the sound and yes it was a Greddy BOV. I eventually went to a bypass just recently but it was fun while I did it. Everyone loved the sound and was in awe to find out it was SC and not turbo

Sorry forgot to say no it didnt open at idle but it was an adjustable BOV so I tuned it right. I would get blowoff at about 2500 RPM or higher.

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Thats why it worked for you because it was a blow off valve. Not a open bypass valve. Not the same thing.

85 SS you basicly made a blow off valve out of a bypass and a check valve thats why it works. A true bypass valve by its self vented will not work correctly. Not saying its not a good idea what either of you guys did, its just not quite what the poster was asking for.

Cobra912 said:

******* update ***********

Got car running today, hooked up bypass to powerpipe, runs like a champ. Thanks guys!

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Great, have fun.

bentley429 said:

Thats why it worked for you because it was a blow off valve. Not a open bypass valve. Not the same thing.

85 SS you basicly made a blow off valve out of a bypass and a check valve thats why it works. A true bypass valve by its self vented will not work correctly. Not saying its not a good idea what either of you guys did, its just not quite what the poster was asking for.

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Yup! In his original post he said Bosch BOV which is why I responded how I did but as time evolved we all came to the same conclusion

That was my problem with the whole thing, you didnt actually have a bypass valve so thats why it was working for you it would just go alittle rich between shifts....

exactly

Cobra912 said:

hey guys I need help again..........

I'v ehooked it back up including a small vaccuum line from the upper intake manifold to the the little fitting on the bosch bypass. BUT........which way is the bypass supposed to mount? in other word which side is which??? through the one hole I can push the plunger down, so which way does this mount??

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Scroll back and look at the pic of how i have mine ran. If you sit it 'right side up' with the vacuum port up, the one on the side comes from the intake and the one on the bottom goes to before the blower and after the air meter.