AARotary

I have seen many who mounts their BOV on the turbo side and lots on the throttle side. Just wondering does it makes a difference in aiding the back pressure on the turbo in either side. My BOV is mounted on the intercooler piping going to the throttle body. Is there such thing as an ideal mounting spot for the BOV.

JoeD

the closer you mount it to the TB, the quicker the spool up will be within shifts. the reason being that the pressurized air doesnt have to go through the IC again.

will there be a drastic and noticeable difference?? probably not.

Johnny

BOV...I'm thinking is on the turbo side...just like the stock bov's.....
POV... pop off vavle would on the TB side...bleeding off excess boost before it gets in there...

AARotary

So wouldn't the POV and BOV have the same function that is to relieve the back pressure of the turbo.

1bad7

no. the BOV only opens when the throttle is closed in order to keep boost (pressure) from going back to the turbo and slowing it down between shifts while the POV only opens at a certain set boost level in order to bleed off excess boost before it gets into the engine.

Toadman

Wouldn't the wastegate serve the same purpose as a POV?

1bad7

they're completely different but they do in fact serve the same purpose, to control the amount of boost the engine receives.

mr_jonboy

Exactly. I guess you could consider a POV being more of a safety piece. It is what they use on CART cars. CART can set a certain pressure and give all drivers the same POV so that they don't run more boost and cheat but most normal people by them for safety.

I have the APEXi BOV. I bought the kit for it to mount it in the FD. It goes very close to where the stock one was but it is definitely bigger and a lot more tight of a fit, but it works.

Johnny

it's a common misconseption that they are they same...but they are not.

POV is a a spring regulated valve designed to open at a specific pressure, say 15psi...thus the engine will never see the fulll pressure on the turbos...just in case you never want the engine to see 15psi...it vents to atomsphere of course..

BOV is a vacuum actuated valve which again vents boost to the atmosphere, but it main use is to lessen compressor surge. and it helps with keeping spool time down.

I think we have one BOV and one charge relief vavle...although I think mazda calls them both charge relief vavle...so if you get a BOV..you only need one...

They are just call noise makers always...if you get a BOV you want it in the sameplace as the stock one...

NickSimcheck

I would think it would be vice versa POV (another term for wastegate?)i've never heard of a "pop off valve" before but the POV by the turbo and the blow off by the intake. cause you wouldn't want over boost to exit right before it comes into the intake. and you wouldn't want the blow off valve right next to the turbo cause like somebody else said it's just making less intercooler pressure, witch means more time for the boost to build up. but i could be talking out of my ***...
Nick

1bad7

well said

AARotary

Maybe the POV works for the stock TT unit but most single turbo eliminates the use of POV and instead we use the BOV. So the BOV and the wastegate is good enough to do what the POV does. I was just wondering Greddy have the POV available for our cars so do need to use the POV and BOV together or just the BOV itself to do the job.

Johnny

I'll writ it again...that sound country enough

POV is like a safety vavle...say you turbo's are running 20psi..but you only want 15psi to the engine...you want a POV...

BOV is for compressor surge like when the throttle body is closed suddenly..it's supposed to help with spool up...

if you wanna get all your boost into your engine...you dont need a POV

AARotary

Thanks for clearing it out. Screwd the POV, I want all the boost going to my engine.

Johnny

well like I said it's for safety...let so you are running 20psi...and something happens and you turbo's start pumping 30psi...then the POV might potentially save you engine...know what I mean...

stripedFD

Does anyone know about them?
it sounds cool!!
try the mp3 at
http://www.nightpager-usa.com/products/blow.htm

DK

iTrader: (5)

And to further confuse folks ...

A "something happens" is the wastegate somehow fails to open (busted solenoid, boost controller broken, or even it gets heat-wedged), so excess boost is produced and sent to the motor ... the POV would prevent the delivery of the excess boost by bleeding it off.

It's basically been said across a few posts in this thread, but I'll sum it up:

Wastegate: bleeds exhaust gas away from turbos in attempt to reduce boost production by not feeding the turbine enough exhaust gas -- this is between the exhaust exit port and the turbine

POV: bleeds off excess boost produced by the turbos somewhere between the turbo and the TB so that it never gets to the motor.

BOV: momentarily bleeds off most boost when the TB is "closed" (shifts, off-throttle) to prevent boost surges in the suddenly closed system that will return to choke the compressor (therefore reducing spoll ... requiring new spool time).

Johnny

yes I remember AARotary wanting a huge turbo, maybe even bridgeport (so goodbye to streetability) etc etc...make sure you get a good wastegate..TIAL come to mind... POV would not hurt for SAFETY

AARotary

So basically it is a good idea to have a POV and not just a BOV, protecting your motor from excessive boost and the other protecting your turbo. Now I am considering the POV as an insurance for my motor.

RedR1

iTrader: (5)

exactly, as stated above, the POV is sort of like a secondary wastegate. It bleeds boost that is not needed. Or the sake of conversation, say a car is running ecu, catback, midpipe, intake, and fmic. Boost spikes would occur often due to the midpipe, but the popoff valve would act as a secondary wastegate, bleeding off more boost.

Basically, the second rubber needed to make sure nothing pops

Johnny

YES exactly

NickSimcheck

Where would you want to put a POV if you got one, on the piping between the turbo and the intercooler? This way the IC doesn't cool air thats just going to bleed, correct? Anybody know who makes good POV's?
Nick

mjw

iTrader: (1)

As stated above, the closer you mount your BOV to the throttle body the better. This provides the quickest possible response out of the BOV, as well reducing any re-spool time between shifts. I have no experience with a POV.. but my question regarding them is this.. how are they adjusted? Are the adjusted like the fly-by-night method used to adjust a BOV? Man it would suck to be trying to eliminate some overboosting and adjust the POV incorrectly, the BOV is one thing.. just some minor compressor surge if it is too tight.

Matt
93 SSM

RPW Motorsports

If you are using a mid-pipe instead of the cat, a POV would be perfect to control those pesky boost spikes so many people seem to be experiancing. In fact I just put one on my friends RX7 last week. NO MORE BOOST SPIKES!!!!

Pressurized

This seems like it would be true, but I looked into buying one from Rotary Performance and they strongly urged that I didn't use a POV to control spikes...

They said it was for safety only and they have more of a tendancy to fail than the wastegate does....