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The mkiv Supra Owners Club

Replica Tial Q BOV


berg

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To be honest i ran no bov on the stock twins and it sounded crap thats why i bought this valve

 

But on the precision its a different story :)

 

Still this is the best sounding bov on the market in my opinion, i think i understand your comment now Nodalmightly ;)

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I swear having no BOV means huge compressor surge which is bad for the turbo and massively reduces its lifespan?

 

No BOV's go Pppssttt! and that is only because someone thought it would be a good idea to NOT re-circulate the air back into the induction system. I believe originally it was used by Cosworth as a way of stopping the noise of compressor surge as Ford wouldn't clear the car for production making a noise that sounded like it was broken. I think CW know the story better than I.

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Compressor surge is a completely different phenomenon to the 'chatter' noise you hear, by running without a bov

There's lots of myths floating around the Internet, but no concrete evidence that it reduces the lifespan of the turbo.

 

/QUOTE]

 

Compressor surge is the chatter noise you hear mate.

 

My thoughts is that BOV's can't open quickly enough to prevent the initial shock on the turbo. Once the BOV opens, the damage (if any) is already done.

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Compressor surge is when the compressor map is out of its efficiency range, and you have a higher pressure behind the compressor wheel, than the turbo can actually produce. If you hear that 'chatter' noise, whilst on boost, then it's bad news.

 

The noise you hear by not running a bov, is pressurised air crossing back over the compressor blades, after the throttle body has been shut. This will not harm the turbo

 

 

 

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Compressor surge is when the compressor map is out of its efficiency range, and you have a higher pressure behind the compressor wheel, than the turbo can actually produce. If you hear that 'chatter' noise, whilst on boost, then it's bad news.

 

The noise you hear by not running a bov, is pressurised air crossing back over the compressor blades, after the throttle body has been shut. This will not harm the turbo

 

 

/QUOTE]

 

Yeah exactly. Pressurised air hitting the compressor blades which are moving in excess of 150,000rpm in the wrong direction is surely gonna cause some form of wear, even if minimal. I'm not convinced personally. I'll always run a BOV!

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Yeah exactly. Pressurised air hitting the compressor blades which are moving in excess of 150,000rpm in the wrong direction is surely gonna cause some form of wear, even if minimal. I'm not convinced personally. I'll always run a BOV!

He wont have that problem with the precision ported cover anyway. Diverts any surge around the blades

 

 

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Yeah exactly. Pressurised air hitting the compressor blades which are moving in excess of 150,000rpm in the wrong direction is surely gonna cause some form of wear, even if minimal. I'm not convinced personally. I'll always run a BOV!

 

Yet you run antilag? Lol

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Sorry Berg, I'm cranky this evening, not an excuse though. I had antilag removed from my cal switch after reading into it a bit more. As for BOV vs no BOV, internet speculation aside, I think it's purely personal preference. In my mind anything that isn't good is bad, and since compressor surge isn't exactly 'good' I think of it as bad. But that's just me. Sorry for being an arse on your post

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Compressor surge is when the compressor map is out of its efficiency range, and you have a higher pressure behind the compressor wheel, than the turbo can actually produce. If you hear that 'chatter' noise, whilst on boost, then it's bad news.

 

The noise you hear by not running a bov, is pressurised air crossing back over the compressor blades, after the throttle body has been shut. This will not harm the turbo

 

 

/QUOTE]

 

Have you not described the same thing twice there though? A greater pressure differential behind the turbo than there is in front of it in both scenarios resulting in the air taking the path of least resistance out through the turbo and making the chatter noise. A surge of air from no BOV is surely more apt than it slowly building up to a dead head when on boost? Would that not be more like compressor stall?

 

Ps sorry for the thread hijack :D

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Have you not described the same thing twice there though? A greater pressure differential behind the turbo than there is in front of it in both scenarios resulting in the air taking the path of least resistance out through the turbo and making the chatter noise. A surge of air from no BOV is surely more apt than it slowly building up to a dead head when on boost? Would that not be more like compressor stall?

 

Ps sorry for the thread hijack :D

Not exactly

 

Compressor surge, is on boost, when the turbo is out of spec. So it's trying to push more boost than the engine can absorb, so the boost pressure is forced back out through the turbo.

 

When you get the chatter through no bov, when the throttle is closed, it's the pressurised air between the turbo outlet and throttle body that travels back out to the air filter. As the air rushes past the face of the compressor wheel, it makes the 'chatter' noise.

 

 

 

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