evilundisguised

Just as the title says... Is a blowoff valve needed for low boost levels (5-6 psi)? In higher boost applications, will the valve open at any boost > 0psi when you let off the throttle?

OBE1 95Z28

If you MAF is located just before the TB, you can run a BOV at any boost level. You didn't tell us what setup you're running; if it's a SC, most installations have the MAF before the blower and you cannot run a BOV as you'll be venting metered air and screw up your air/fuel ratio. Your bypass valve recirculates unused boost when you close the TB blades.

evilundisguised

I'm still NA at the moment, but thinking ahead... how about for an STS system? Obviously I would need the BOV to be placed before the MAF sensor, but is it really needed with only 5psi of boost?
Claimed "benefits" of a BOV: (please add if I'm missing something)
1- prevent damage to turbo by pressure backsurge
2- maintain turbo rpms between shifts w/ a manual trans
3- make sneezing noise when it blows off

does anyone have any firsthand experience as to whether or not any of these things are pertinent to a low-boost STS system?

viper03af

http://www.turbov6camaro.com/BOV.html << good read on how they work

my turbo surges at only 3 psi boost if i don't let off the gas all the way

evilundisguised

EVEN if, or ONLY if you don't let off the gas all the way? Is 3psi your max boost?

viper03af

only if, the BOV does not see vac and never opens..... point is its going to surge at any boost level....

my max boost is 17 psi

evilundisguised

Ah ok. So then the question still is whether or not there will be any benefit to having one with boost levels not exceeding 5 psi...? Will I be risking damage to anything (turbo parts, throttle plate...)?

viper03af

surge is hard on the turbine over time its wheres it out faster

viper03af

IMO any system should have a BOV, some people will say autos dont need them but i disagree.

i think any boost system should have a BOV.... even SC systems

evilundisguised

That's fine, and I respect your opinion... I just prefer to have as much information, quantitative or qualitative, as possible when learning about something. So keep it coming

snorkelface

I guess I still don't understand why you would need a BOV when utilizing a bypass valve.

viper03af

BOV vents into the air

bypass vent it back in front of the maf...... if you vent into the air after the maf the car goes rich and dies

blown383

Simply put... BPV for supercharger and BOV for turbo.

-B

Roadie

except in the case of blow-through MAF... Then BOV before MAF.