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How Much Boost Is The Stock Bov Good For >>>

suburban drifter

By suburban drifter,
in Queensland

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suburban drifter Community Regular

suburban drifter

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heya.. i just got my car back after a turbo upgrade and my tuner as blocked off my bov ;) we all know what happens then .... he said that the stock one wont handle the exstra boost and might leak some...my question is how much power can the stock rb25det bov handle... im going to be running about 16psi max, thanks for feedbak

suburban drifter Community Regular

suburban drifter

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any 1 ????????????? i need to know the stalling is killing me and might actually kill me soon as i found today while comming down a hill that when you car stalls your brakes go rock hard and then you gotta hand break it ;). turns a few heads tho haha

Revhead Grand Master

Revhead

Posted
Posted

Geez mate, have some patience, you only posted the question at 7.23pm on a Friday night!

Anyway the stock BOV can vary a bit in terms of how much pressure it'll hold, it'll probably start to bleed boost over 10psi but some can go higher. There's a trick where you can bend in the top of the BOV (to preload the spring) which will help it hold more boost, I did that on my old car and it worked fine at well over 16psi. It may have bled a bit but it seemed to do the job fairly well for a part that's meant to hold 7psi.

Either way though I don't think a blocked BOV should cause your car to stall all the time, I'd be wondering if they've left something open to the atmosphere or whether you might have some other problem. Try to unblock the BOV and take it for a drive to see if your stalling issue goes away. If it does, look for leaks - if you disconnect the return line and don't block it you'll have stalling issues for example. You can also try resetting the ECU, instructions for that are elsewhere on this site.

R33S2 Grand Master

R33S2

Posted
Posted

Before I changed to a Turbosmart BOV I was running 16psi on the standard one, afterwards I was running 17-8 and could boost well above that, which I really couldnt on the standard one, it just bled out.

Revhead Grand Master

Revhead

Posted
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what did you use to bend the top of the bov in with..

and how far do you bend it in ... thanks mate

you put it in a vise afaik. and its not reeally a lot
Yeah you don't bend it in a lot, and I just used a vise.

It's certainly not the "best" way to do it but it did the job for me on the cheap - I had intended to swap to a proper recirculating BOV (which probably would have given me better results) but sold the car before I did that. What I'm saying is don't look at bending the top of the BOV as a long-term fix, but it might get you out of trouble for now :banana:

psi Experienced

psi

Posted
Posted

huh? perhaps I have missed something....?

the BOv is plumbed into the intercooler pipe AND the plenum, so, how is it possable that it could ever leak if it had the same pressure on BOTH sides of the BOV under boost? it has pressure from the intercooler pipe (boost) and it has pressure from the signal line which also reads (boost)? the only difference is the throttle body.. it has a (granted not so strong spring) to hold it shut, so, if it had the same PSI on both sides, where exactly is the boost going to go?

Hav I missed something? Cos, I'm happily running 16PSI with my hi-mount with no issues what so ever..?

somebody alot smarter than I, had better have a good answer cos I dont!

Revhead Grand Master

Revhead

Posted
Posted

When the BOV opens, it allows air to return from the pressurised side (ie, between turbo and throttle body) to the unpressurised side (ie between the AFM and turbo). The weak BOV spring means it can be forced open at high-ish boost levels which means you can, for want of a better term, "lose boost". It's able to leak from the pressurised area back out in front of the turbo, virtually the same thing as if you have a lightly-sprung atmo BOV except that it doesn't stuff the AFM readings.

I ran 23psi and I think I could hear it opening, could be wrong though because there was an awful lot of other noise happening at the same time :)

R33S2 Grand Master

R33S2

Posted
Posted
PSI

the BOv is plumbed into the intercooler pipe AND the plenum, so, how is it possable that it could ever leak if it had the same pressure on BOTH sides of the BOV under boost?

Its plumbed into the pipe from the air filter to the turbo intake, so it is greatly varied on each side of the bov, intake = suction, plenum =pressure.

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