Running 2 BOVs

[TurboChrged93]

Looking into running 2 blow of valves. Currently using the Apex-i Twin Chamber and no matter what kinda of adjustment I'm getting absolutely HORRIBLE compressor surge. In need to doctor the situation... thinking of adding another blow off valve mounted closer to the turbo. Running 2 simultaneously. Any experience, input, gripes, or flaming? Please do.

 

[UCspyderGS-T]

Looking into running 2 blow of valves. Currently using the Apex-i Twin Chamber and no matter what kinda of adjustment I'm getting absolutely HORRIBLE compressor surge. In need to doctor the situation... thinking of adding another blow off valve mounted closer to the turbo. Running 2 simultaneously. Any experience, input, gripes, or flaming? Please do.

No, no one runs two bov simultaneously. When does the compressor surge start. Under what loads? A buddy of mine's car compressor surges if he is in a high gear and tries to build boost when cruising at a rpm lower than when the turbo starts to spool up. Ex. if he is in 3rd gear at 2500 rpms and the turbo spools at 4000 rpms it compressor surges. It is b/c of his turbo, the particular brand. Other than that you could try a different bov.

 

[PieEyedPiper]

..wait your friend gets comp surge before his turbo even spools?

 

[UCspyderGS-T]

..wait your friend gets comp surge before his turbo even spools?

I meant to say as the turbo is spooling up, it compressor surges.

 

[TurboChrged93]

Compressor surge occurs all the time unless I'm WOT full boost and then release the throttle quickly or press the clutch.

Doesn't matter if its 10% throttle, 50%, 60%. Unless its over 15psi or over, it surges.

Even surges horribly before it even builds boost.

It's a bullseye 50 trim.

You can hear the surge for a good 4 - 5 seconds continously.

 

[VelocitàPaola]

Even surges horribly before it even builds boost.

Wait. What?

Define what you think surge is for us please...

 

[X-Rated GST]

I've actually read in the supra forums that the MKIV's run two bov's to eliminate compressor surge. They usually run the stocker and then an aftermarket one. But since we're DSM's here....

 

[gst25401]

2 bov are fine that will definetly fix your problem, mazda guys do it all the time. It is usally implamented with extreme boost ,but the purpose u need it for will work.

 

[daveyfx]

I can't say for sure how the Apex'i BOV works but I'm assuming there's some way to soften it up a bit. If you've already tried this and you're leaking from the BOV before you reach peak boost then I think you should look into switching to a more effective BOV... rather than simply adding another one.

 

[Lordpaxin]

I 'had' the Apex'i Twin Chamber, for a while and never could get it right.

Switched to a Greddy Rs and no probs.

 

[DSMcamaro]

Something i remembered seeing before.
http://www.dsmtuners.com/forums/showthread.php?t=184920&highlight=2+BOV's

 

[TurboChrged93]

Wait. What?

Define what you think surge is for us please...

LoL. Are you testing my ability to comprehend compressor surge. When I let off the gas. And the throttle body plate closes. The air goes backwards through my intercooler pipes and comes back out the turbo inlet pushing a "bad" negative force on my compressor wheel. Because my bov is not oppening correctly. I've messed with the adjustment, and can't seem to get it right because if I go any softer it simply leaks. It would be cheaper to add another bov then for me to reflange my pipe and get another one.

And to answer your "Wait. What?" It surges before I actually build any boost on the gauge. Compressor surge is not a problem when I build about 10 psi. It anywhere below that and even under vacuum partial throttle, no boost.

Got it? Good.

 

[VelocitàPaola]

No no, I trust your ability to properly diagnose your car, I just don't understand what's surging when there's no boost.

 

[sbcxtreme]

can someone clear up what surging is and what causes it? seems like there is mixed opinions?

 

[DGajre777]

can someone clear up what surging is and what causes it? seems like there is mixed opinions?

When I let off the gas. And the throttle body plate closes. The air goes backwards through my intercooler pipes and comes back out the turbo inlet pushing a "bad" negative force on my compressor wheel.

What ^^^ said.


Here is some more info...

Surge
The point at which flow at a given pressure ratio drops below a certain level and the flow becomes unstable. This results in surging boost, where the compressor seems to be "gulping" air. Surge can be quite harmful to the compressor, so is to be avoided at all costs.

Blowoff Valve (BOV or Pop Off Valve)
Note: This term is often erroneously used in place of "Bypass Valve!" A blowoff valve is a pressure relief device used to save the engine when overboost occurs. It is actuated solely by overboost, with no other controls necessary. In a supercharger system, a blowoff valve can be used as a means of dynamic boost control (static boost control is achieve by choice of supercharger drive ratio). A BOV might be added to a boosted system to protect against backfire damage to a super- or turbocharger. It can also protect against a stuck wastegate valve by sacrificing the turbo to overspin.

Bypass Valve (Dump Valve, Anti-Surge Valve, Recirculating Valve)
(Note: Often erroneously called a "Blowoff Valve.") A pressure relief device actuated by post-throttle body manifold vacuum. The purpose is to reduce or eliminate high pressure in the intake tract between the turbocharger outlet and the throttle body, thus maintaining the momentum in the turbo for reduced lag. Another important reason to have a bypass is to eliminate pressure spikes, which can pop hoses, can rupture the intercooler and, worst case, can induce such high torque on the compressor that it breaks the turbine shaft.

Source: http://not2fast.wryday.com/turbo/glossary/turbo_glossary.shtml

Most often a Bypass Valve is called a blow off valve, but in DSMs (unless you are venting), it is a compressor bypass valve, not a blow off valve.