how does the pressure relief valve on manifold work, does it work like bov? Some original photos have not been recovered yet.

pretty much, it wont let it spike over 9-10psi.

builds up pressure , then at 9-10psi it releases i belive its a safety measure to stop overboosting

It doesn't work like a BOV though, because it's on the wrong side of the throttle butterfly.

Quote: Originally Posted by jordy It doesn't work like a BOV though, because it's on the wrong side of the throttle butterfly. It essentially does the same job but instead of releasing air between turbo and throttle body (BOV) it's releasing the build up inside the manifold.

^ exactly, its the same principle.

Quote: Originally Posted by Psi_Wagon ^ exactly, its the same principle. it's not the same principle. a BOV stops the turbo from stalling caused by the back presure went you get off the gas

No a blow of valve is used to reduce compressor surge & reduce wear on your engine...

The factory pressure relief valve uses positive pressure to open and a bov uses positive pressure as well as vacume to open. The two are designed to do different jobs and are located in different parts of the inlet.

Quote: Originally Posted by high_comp it's not the same principle. a BOV stops the turbo from stalling caused by the back presure went you get off the gas lol

dont even need a wastegate...just run a higher pressure valve in the plenum lol

Quote: Originally Posted by PROGMH It essentially does the same job but instead of releasing air between turbo and throttle body (BOV) it's releasing the build up inside the manifold. It's like saying a basketball is a football... I mean, they're both balls full of air. But would you play a game of basketball with a football? A BOV and the pressure relief valve perform two different jobs, and they are located in two different positions. The pressure relief valve also doesn't need to see manifold vacuum to open, whereas a BOV does. To say they are the same is incorrect.

I thought atmosphere venting was illegal that's why you can't have a BOV. So why does RTA or Vic Roads kick up a stink about atmosphere venting. Basically the pressure relief valve is venting excess pressure kind of like the BOV. Is the reason why the RTA or Vic Roads say you can't have a BOV is because the car wasn't released with a BOV?

Quote: Originally Posted by jordy It's like saying a basketball is a football... I mean, they're both balls full of air. But would you play a game of basketball with a football? A BOV and the pressure relief valve perform two different jobs, and they are located in two different positions. The pressure relief valve also doesn't need to see manifold vacuum to open, whereas a BOV does. To say they are the same is incorrect. Far out. I meant the actual device is similar to a BOV. It releases pressure! Clearly they have a different purpose because people use both at once. If you re-read what I originally wrote you would see I stated the difference in what they do. Your basketball / football theory fails big time.

ok i know what a blow off valve is and what it does all i wanted to know is how standard releif valve works.so if i put a boost controler that valve wont let any more than 10psi in does it have to be removed for more boost

Removed, welded, blocked off in some way, yes.

Quote: Originally Posted by HTURBO I thought atmosphere venting was illegal that's why you can't have a BOV. So why does RTA or Vic Roads kick up a stink about atmosphere venting. Basically the pressure relief valve is venting excess pressure kind of like the BOV. Is the reason why the RTA or Vic Roads say you can't have a BOV is because the car wasn't released with a BOV? because in normal driving conditions the overboost valve is not doing anything ( no venting ) its there ONLY as a safety measure. try arguing that your wastegate and/or bov are there for safety reasons :P the reason bov's (not plumbed back) are illegal is because its not just air that comes out of them, its air + oil vapour.

once boost pressure overcomes the spring pressure it opens, a blow off valve without a vacume/boost feed into it will act the same way in that once pressure overcomes the spring tension it will open.

I went to a plumber and got a brass plug/bung cost $7 and worked a treat Some original photos have not been recovered yet.

Quote: Originally Posted by SIKVLT I went to a plumber and got a brass plug/bung cost $7 and worked a treat Ripped off, 3/4 BSP thread, get a brass plug from Bunnings, probably is about $7 though. Or, to keep the factory look you can have the inside welded shut and throw it back in knowing it wont work. Basically its safety device from factory that prevents the engine over boosting should there be a problem with the waste gate, it basically by passes the air out the manifold, instead of into the engine. If your planning on running higher than factory boost you will need to do something about it. A good actuator for your waste gate will be fine, or a boost controller. Dont forget to get it tuned if you run more boost than factory also. Some original photos have not been recovered yet.