Bypass Valve Question

[BlackLX]

Ok- So last summer I added the bypass valve into my supercharged set up, for safety purposes more than anything.

I was just curious, how come a bypass valve doesn't make the same noise as a blow-off valve in a turbo set up? Can it make the same pishhhhh noise when shifting? I know it sounds dumb, but I was just curious.

[1slo5.0]

A bypass valve vents the air back into the inlet. A blow off valve vents the air to the atmosphere producing that pisssshhhhhhhhhttttt noise.

[BlackLX]

So a bypass can't make that sound then?

Why does the bypass vent back into the inlet and not the atmosphere?

[1slo5.0]

So a bypass won't make that sound then?

Why does the bypass vent back into the inlet and not the atmosphere?


No, it won't make that sound. It vents back to the inlet because that is what a bypass valve does.

[quietflow]

I am not sure if 6-8lbs is going to make a really loud noise:)

[BlackLX]

This summer I will be going up to around 9lbs, I wonder what would happen if I just left the tube off the inlet where the bypass relieves the excess air to?

not a big deal I suppose...I just thought that blow-offs sound tight.

[Mark302]

Because it is a mass air car it has to go back into the pipe because the meter has already read it is there. In Mikes truck his blows off into the atmosphere and it sounds like something it wrong with it. (kind of stupid) But he has no choose.

[Greg@GLD]

Ok- So last summer I added the bypass valve into my supercharged set up, for safety purposes more than anything.


Mikey, not to be a dick, but... what other reason would there be? :D
In theory, on a manual trans car, it would be better to run without one so that you don't dump boost on every shift (unless you do full-on, never-lift powershifts) but even then, at the end of the 1/4 mile when you let off the gas, you could explode your impeller, so you need one. I think with Powerdynes, they do not include one with 6 PSI kits.

FWIW guys, I had my tube that leads back to my powerpipe pop off once, and indeed, it sounded like a blow-off valve. Actually did sound kinda cool...

Mikey, maybe you could buy one of those ricer poser deals that mimic the sound of a blow-off valve in operation. They actually do sell such a beast. It's on the same page as the fake nitrous purge kits. :beer:

BTW: Mark was right on about why you should not vent to the atmosphere.

[BlackLX]

FWIW guys, I had my tube that leads back to my powerpipe pop off once, and indeed, it sounded like a blow-off valve. Actually did sound kinda cool...

Mikey, maybe you could buy one of those ricer poser deals that mimic the sound of a blow-off valve in operation. They actually do sell such a beast. It's on the same page as the fake nitrous purge kits. :beer:



I think I'll stick to my sleeper sound in that case. I don't have money to waiste on useless crap :alc:

Maybe I'll pull that inlet tube off for the hell of it though and see what happens sometime this summer.

[Mark302]

Mikey, not to be a dick, but... what other reason would there be? :D
In theory, on a manual trans car, it would be better to run without one so that you don't dump boost on every shift (unless you do full-on, never-lift powershifts) but even then, at the end of the 1/4 mile when you let off the gas, you could explode your impeller, so you need one. I think with Powerdynes, they do not include one with 6 PSI kits.

FWIW guys, I had my tube that leads back to my powerpipe pop off once, and indeed, it sounded like a blow-off valve. Actually did sound kinda cool...

Mikey, maybe you could buy one of those ricer poser deals that mimic the sound of a blow-off valve in operation. They actually do sell such a beast. It's on the same page as the fake nitrous purge kits. :beer:

BTW: Mark was right on about why you should not vent to the atmosphere.

I need to have a switch that doesn't let the blow off open until the end..... :D

[Jesse James]

Other than the psssch sound, "some like it some don't" other reasons for the bypass valve and blow off valve:

By using a bypass valve on a supercharged application when you lift off the throttle from a WOT position, the bypass valve does a couple of things;
it helps to prevent overspinning the supercharger while shifting and if you shift relatively qwik maintains the same impeller speed so your not waiting for the supercharger to spin back up to the "sweet spot" in the boost range.

On a turbo car the purpose of a blow off valve is very similar. The blow off valve releases pressure to the atmosphere when shifting to prevent boost spikes and destroying the impeller. The temps of the turbo gasses vented to the atmosphere allow the turbo to injest cool air on WOT shifts vice hot compressed gasses from a bypass valve. The blow off valve also allows you to remain in the "sweet spot" of boost so there's not as much of a delay "waiting for the turbo to spin back up."

The time you wait for a supercharger or turbo to spin back up is minimal with lower boost applications and therefore a bypass or blow-off valve is not really needed in a lower boost application.

As Greg mentioned, the safety factor here is like insurance for your blower car. I had a bypass valve on my old S trim I was running a max of 12 psi.

My turbo car made 6-8 psi stock and didn't have a bypass or blow off valve. Now I'm running around 16-17 psi at WOT and have a BOV pssssch :p

No performance gains really, just an insurance policy for my turbo. :burnout: :cool: Let alone the loud backfire from unburned fuel out the exhaust pipes on a WOT 2-3 and 3-4 shift. LOL