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big single twin bovs?????


supradibbs

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been reading up a little on this just thought i would see what your opinions are

 

there is alot off people out there that think running twin bovs on big hp cars can dramatically reduce compressor surge,as i will be running over 600hp was thinking going down this route using 2 hks ssqs one on the ic pipe before the intercooler and one after the intercooler by the throttle body

 

whats your views on this

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The BOV's are only good for handling around 500bhp, and lets be honest we all enjoy a good blow job, so two is probably a very good idea.

 

I've got one on the hardpipe going to the throttle body, but I've seriously considered putting one on the pipe just before the intercooler as well....

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Fortunately I can access this place from work still though :) (I'm not the one on holiday :( )

 

Being Mr Function-Over-Form I'd say use one BOV until you get compressor stall and can directly attribute it to the one BOV not shifting enough air out the door in time. I've never heard of anyone needing two before.

 

-Ian

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With big singles two is reccomended unless you dont mind compressor surge/Turbo stall... as one BOV wont be enough to release all the air, so thus some is forced back into to the compressor and hits the blades causing turbo stall...hence the chopping/pigeon noise.

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A BOV won't affect compressor surge, that's a sizing V airflow requirements issue. I have never, and will never, run a BOV on any of my turbo engines, IMO they are extra weight, plumbing and hassle and do sod all for spool up or anything else other than reducing compresssor noise on throttle lift off, which is what they were designed for anyway. Unless it's a "silly" vent to atmo one which just makes annoyiing noises :) 3 of the UK's topmost turbo experts agree, it's not another of my bee in bonnet dogmas!

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A BOV won't affect compressor surge, that's a sizing V airflow requirements issue. I have never, and will never, run a BOV on any of my turbo engines, IMO they are extra weight, plumbing and hassle and do sod all for spool up or anything else other than reducing compresssor noise on throttle lift off, which is what they were designed for anyway. Unless it's a "silly" vent to atmo one which just makes annoyiing noises :) 3 of the UK's topmost turbo experts agree, it's not another of my bee in bonnet dogmas!

 

interesting info Chris, i personally hate the sound of BOV's so i'll stick with just the one then. I love the compressor noise:)

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They seem to love the big BOV setups in the US chris, or is that just there mentality? As they do have some seriously powerful cars over that side of the pond! Hhmm maybe dusty or Jarrett may want to comment?? I had a Big Turbosmart BOV on my track skyline and tbh did not notice any diff exept the noise of course!;)

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A BOV won't affect compressor surge, that's a sizing V airflow requirements issue. I have never, and will never, run a BOV on any of my turbo engines, IMO they are extra weight, plumbing and hassle and do sod all for spool up or anything else other than reducing compresssor noise on throttle lift off, which is what they were designed for anyway. Unless it's a "silly" vent to atmo one which just makes annoyiing noises :) 3 of the UK's topmost turbo experts agree, it's not another of my bee in bonnet dogmas!

 

But these arent like Rally cars with 360 Deg. bearing trubos, so surely the turbo stall caused by not having a BOV isnt good for stock ceramic turbos when running high boost..are they not prone to shattering this way...? any thoughts?

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3 of the UK's topmost turbo experts agree, it's not another of my bee in bonnet dogmas!

 

Graham Bell and Corky Bell (no relation) don't agree with you :) I bypassed my stock BOV once with the hybrids in place and even just revving it up at standstill generated such a hideous noise from the turbos (ratch-ratch-ratch-ratch) as they stalled (not surged ;) ) on liftoff. My mechanical sympathy bone made me fit a BOV. Some rogue bling gene made me fit the purple fin insert and aim it out one of the bonnet vents :D

 

But I still maintain that all those poeple thinking of getting a second one are just doing it for willy waving, because I see no :search: posts in tech asking what that ghastly noise is when they lift off....

 

-Ian

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Not necessarily true. A good few things are in place to combat NVH or emissions so it's nicer for the average punter. The car/engine may not necessarily "need" them. Expansion chambers on the intake, balancer shafts in the engine, crankcase ventilation, charcoal canisters, exhaust gas recirc, CATs, silencers, sound deadening... :D

 

If the only problem with shutting the throttle on a boosting turbo is that ghastly noise then the BOV may be in there only to stop the noise. I still reckon it's bad for the turbo though ;)

 

-Ian

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well I will have the best of both the nice phissst bov and chatter from the WG so I'm all happy.

 

Do see your point about them doing things to make the buyer happy.

 

Lol plump in another BOV and the chatter will go away!

 

That 'Wastegate Chatter' is actually turbo stall you are hearing, there is no such thing as 'Wastegate Chatter' its just what people refer to it as.

 

Your BOV is unable to release all the air from the free spinning turbo when off throttle (as the engine does not require it obviously) this is normally the case with singles as you have a much greater volume of air, so part of the air that could not be released surges back through the compressor and hits the blades...hence the chopping noise you hear which is commonly known as 'wastegate chatter'.

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