Blow Off Valves  

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FHA57
  • FHA57
  • sierra on steroids
  • Member No.: 11,723
  • Joined: 19-August 04
  • Posts: 676
  • From: australia
Post #1 post 29th October 2004 - 06:21 AM
just so that every 1 knows i have just been fined for my blow off valve i live on the sunny coast the government has sent out a notice too all traffic police saying that they need to crack down on blow off valves and excessive noise because they have had complaints about them $240 fine and 2 points not impressed but then again its my fault i wasnt being stupid they just heard the b.o.v neway just so ne1 on the sunny coast cruise knows that they may get done.

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(> <) <=== Copy bunny into your signature so that he may obtain world domination!

IF YOUR BEING A DOUCHE U DESERVE TO GET RAMMED!!!
Ruffels
Post #2

what if you have one of those fake show off valves tongue.gif , do you still get $240 fine and 2 points?
lol
-Ruffels

racer by night
Post #3

bah who needs bov's anyway... i would rather hear the turbo flutter , best sound ever

Hoon
Post #4

Just get a hybrid plumb back job....turn it and make it squeel whenever you want.

BozzA
Post #5

Does my NA Honda have one of these blow up valves??? unsure.gif Should i be worried??? sad.gif

Hoon
Post #6

Be worried if you have one of those electric ones laugh.gif

BozzA
Post #7

*goes and pulls out electric bov out of shitty honda*

Sure glad i dont have one of them...... thumbsup.gif anymore...

TwinCam16
Post #8

That flutter sound is actually a very bad thing, for the turbo anyway.

Just make sure you have a plumb back and they cant touch you wink.gif

_Insane089_
Post #9

whats a plumb back?

_Insane089_
Post #10

seriously..... blink.gif

QUOTE (_Insane089_ @ Oct 30 2004, 09:24 AM)
seriously..... blink.gif

Instead of just venting all the gas to the atmosphere (and making silly noises at the same time) it 'plumbs the gas back' to your engine.

It's the most sensible option too, because a normal atmo BOV messes with something (too early in the morning, i can't think, is it the AFM? forgive me if i'm wrong)

QUOTE (TwinCam16 @ Oct 30 2004, 07:52 AM)
That flutter sound is actually a very bad thing, for the turbo anyway.

Thats debatable smile.gif

... And has been debated, time and time again.

Ahmad
Post #13

i thought all turbo cars have a stock bov... i dunno much about cars... sad.gif but omg that sucks

the red krawler
Post #14

Not all cars came with BOVs standard, see: VL Turbo, Cordia, etc

Pretty much anything after the late 80s DID come with factory BOVs, but they were all plumb back, meaning the compressed air from the turbo gets blown back into the inlet side of the turbo to be recompressed, instead of getting stuck between the turbo and throttle body and causing the "flutter" noise as air pulses back and forward. Apparently this is bad for turbos because the surging causes stress on the turbo bearing. Some disagree.

Pretty much all EFI cars run MAF (mass air flow) from factory, instead of MAP (manifold aboluste pressure) that most aftermarket ECUs run. MAF works by using an AFM (air flow meter) to read the amount of air entering your engine. This AFM is normally right near your air filter. The problem with an atmo venting BOV is that the AFM is reading, say, 1000cfm of air entering your engine, but the BOV is dumping most of it out into the air (making a cool ptscht! noise). So the computer pumps a whole lot of fuel into the engine to burn with the 1000cfm of air but there is only, say, 200cfm left. Therefore, you run super rich and blow black smoke.

AFAIK, this is why they are illegal in QLD more so than noise? In NSW it is defaintely noise too. But the main problem is the fact they fux0r with your emissions and as such may have made the car illegal as it pollutes the air too much. Factory specs say it dumps out 50 naughty atoms a minute, but with an atmo vent BOV its actually dumping 60 naughty atoms. And these atoms go and have naughty atom babies which fight the evil ozone layer with their CFC ray guns and Mr Sun comes flying through the holes and sets fire to ants through magnifying glasses, thus killing the little champions who clean up dead bodies which means the dead bodies come back to life, 'dawn of the living dead' style, and kill all humans. And that is why you shouldnt count your chickens before they hatch.

QUOTE (_Insane089_ @ Oct 30 2004, 09:24 AM)
seriously..... blink.gif

plumb back sends the compressed air back to the intake instead of the atmosphete.. its not "gas" as 70XIN said.. its just compressed air stuck between your turbo and t/b when the t/b is closed.. unless u wanna get technical and say "air/oxygen IS technicaly a gas.." then yes its gas biggrin.gif hahaha

QUOTE (30OTT @ Oct 30 2004, 11:04 AM)
i thought all turbo cars have a stock bov... i dunno much about cars... sad.gif but omg that sucks

your aloud to run a after market bov but it has to be plumb back or it can be atmo BOV but is not aloud any trumpets or slits to inhace the noise they make

Ahmad
Post #17

ohhh ok plumb back it is sunny coast cruise is tomorry im guessing will be a lot of bov's going off everyone better watch out

sidewayz
Post #18

AFAIK, this is why they are illegal in QLD more so than noise? In NSW it is defaintely noise too. But the main problem is the fact they fux0r with your emissions and as such may have made the car illegal as it pollutes the air too much. Factory specs say it dumps out 50 naughty atoms a minute, but with an atmo vent BOV its actually dumping 60 naughty atoms. And these atoms go and have naughty atom babies which fight the evil ozone layer with their CFC ray guns and Mr Sun comes flying through the holes and sets fire to ants through magnifying glasses, thus killing the little champions who clean up dead bodies which means the dead bodies come back to life, 'dawn of the living dead' style, and kill all humans. And that is why you shouldnt count your chickens before they hatch.



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hahahaaha, best descritpion ever! laugh.gif

TwinCam16
Post #19

in an air flow meterd car, if you use a plumb back, you wont have ANY emmisions problems, in a map sensord car you can use vent or plub back and not have any problems. the only time you will have a problem with emmision is when you use a venting bov to an air flow meterd car.

as for sound, well you get that tongue.gif the plumb back they cant touch ya for smile.gif

FHA57
Post #20

the cop wasnt interested in emissions lol he just hated the noise also he said any1 cutting "laps" is accociated as a hoon in his eyes they just dont like the noise so im tryn to do the right thing by u guyz and warn u b4 the cruise tongue.gif he didnt like the boostcruising sticker on my car either dunno why? he said they come on this site al the time yeah im just gunna get a steath fx lol the actual fine was so evry 1 knows wilfully drive a motor vehicle in a way that makes unnecessary noise (blow off valve) took him about 10mins to find it with the torch lol he was looking at my plenum and i just said wat ru looking for? and he said a "blow out valve" and i almost laughed in his face poor guy tryin to do his job they should train them better so they dont look like idiots and good luck tryn to get a tt soarer to flutter or (turbo back spin) l8er dudes thumbsup.gif

QUOTE (TwinCam16 @ Oct 30 2004, 07:52 AM)
That flutter sound is actually a very bad thing, for the turbo anyway.

yes, its bad for non-ball bearing turbo's, but it doesent affect ball bearing turbo's in anyway.

QUOTE (mr.mx6 @ Oct 30 2004, 12:30 PM)
yes, its bad for non-ball bearing turbo's, but it doesent affect ball bearing turbo's in anyway.

I call BS on that smile.gif

neil_se
Post #23

Here's an interesting quote on BOVs from Sydneykid on SAU.

"Well, the theory is by having a recirculating BOV, the hot air goes around again. Whereas an atmospherically vented BOV gets rid of the hot air and makes room for fresh (colder) air. There is also the cooling effect from the overly rich mixture that the engine runs after the atmosphere BOV has vented. Some people say that this overly rich mixture also reduces lag on gear changes as it burns in the turbo and helps spool it up."

MuchDa-Bogan
Post #24

has any 1 got a pic of a plumb back .. or a custom job? so i can make my bov a legal 1 biggrin.gif

Nvious
Post #25

speaking of BOVs.. i got a Monza SSQ BOV for sale..

QUOTE (neil_se @ Oct 30 2004, 01:33 PM)
Here's an interesting quote on BOVs from Sydneykid on SAU.

"Well, the theory is by having a recirculating BOV, the hot air goes around again. Whereas an atmospherically vented BOV gets rid of the hot air and makes room for fresh (colder) air. There is also the cooling effect from the overly rich mixture that the engine runs after the atmosphere BOV has vented. Some people say that this overly rich mixture also reduces lag on gear changes as it burns in the turbo and helps spool it up."

I disagree somewhat on that theory too.

The richer mix normally causes the car to run fairly shit, depending on the AFM/ECU combo used. I know on R33s they are particuarly bad running an atmo BOV on stock computer and AFM. Bad to the point of stalling the car at anything (read: reversing, driving up steep driveways, etc) other than high rpm/high boost (read: racing).

The mix also isnt that rich that it "burns in the turbo" ala anti-lag.

Annnndd, as the air expands it cools. Therefore, as it expands passing through the plumb back BOV into the inlet pipe, its going to cool. Its not like its a lot of air (read: a whole combustion cycle worth of air) being recirculated many times, its a small puff that expands and gets recompressed. Slightly hotter than before? Possibly. But how arse must your intercooler be if it cant get rid of that tiny amount of additional heat?

For a final point, we have a 33 and stock plumb back bov. We used to have a blitz atmo vent bov, but went back to the plumb back because the car went harder, had less lag between gears and we stopped receiving "turbo whistle" (their words) defects smile.gif

TwinCam16
Post #27

I agree with Krawler as far as driveability goes with AFM cars and venting bov's, i have the V port BOV on the sss and you have to make it idle or risk stalling it. you get used to it after a while tho.


You cant just make ya bov a pumb back, well some you can but most ya cant.

user posted image
This is a venting bov, not legal.

user posted image
This is a plumb back, is legal

user posted image
This is both, theory is, the trumpet side is actually up higher than the pumb back port, meaning you have to do a dam big lift off, to make the trumpet side vent, well so the theory goes with the GFB stealth one anyway, altho still illegal.

user posted image
This is the mother of all. I would pay the fine to see a cop put his head in front of this sucker when it goes off.

QUOTE (mr.mx6 @ Oct 30 2004, 12:30 PM)
yes, its bad for non-ball bearing turbo's, but it doesent affect ball bearing turbo's in anyway.

And yes thats a bog 10 4 on the bullshit

scan
Post #29

let the dam dumb arse coppers fine ya. wait 3 months down the track when there usen import cars to chase us down the highways when there bov goes off say suck that coppa and have a nice court fight to make cops lay off ya. and if u dont have the 100 thousands of dollars to do that make it plumb back ha ha ha

TwinCam16
Post #30

I think you need to wake up and change hands dude....

FHA57
Post #31

i think the whole thing is is that i was on the 1 year probo i finished it got all my points back and they tried to fine me for my wing i got outa that and now they have fined me for the b.o.v wat can i say i cant win lol looks like its the stealth fx for me and i was just bout to buy my mates apex ssq but now im not sad.gif damn cops! it realy annoys me as he didnt even know wat he was talking bout but he could still fine me dunno.gif oh well mebe theyl leave me alone know wiggle.gif wavey.gif but he also mentioned the boost cruising sticker on my car and said they r on this site all the time! unsure.gif

TwinCam16
Post #32

tell us something we dont know....

who knows, if they stay on here long enough, the might actually learn a few things and know what they are talkin bout

QUOTE (TwinCam16 @ Oct 30 2004, 07:19 PM)
tell us something we dont know....

who knows, if they stay on here long enough, the might actually learn a few things and know what they are talkin bout

i think your right, they definately know what they are talking about. *shakes head walks away* at least someone does.....

FHA57
Post #34

lol good one twin cam 16 do u know my bro ampersand cos im his little brother wiggle.gif tunes.gif

the red krawler
Post #35

Oh god. A mini Toad.
I'm picturing a small goatee.

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