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Bov's And Boost

macca20042
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macca20042 Apprentice

macca20042

Posted
Posted

hust wondering.. what is a safe boost to have through a turbo without the aid of a BOV. i dont mind the whole woosh sound they give off its just that p platers and BOV's and cops dont really match very well.. i would have thought about 10-12 psi would be ok as skylines are cop bait enough as it is!! anything like links or just general info or estimations is good

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R31Nismoid Grand Master

R31Nismoid

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Your worried about a woosh with a pod and a stock BOV?

Take OFF the BOV and you add 110% more attention to yourself dude.

If you dont like the noise, go back to a stock airbox with a good panel filter. It'll probably be better than the pod you have there now :D

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sh@un Grand Master

sh@un

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...and blocking off the BOV will make a loud chattering noise on gear changes....

yeah

that's compressor surge- one of the main reasons manufacturers fit BOVs (or compressor bypass valves) in the first place.

put it this way- the turbo doesn't really like having to deal with air suddenly try to rush backwards through it while it's spinning at ~100,000rpm

'dose' ftl

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Pauly33GTS-t Veteran

Pauly33GTS-t

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Posted
yeah

that's compressor surge- one of the main reasons manufacturers fit BOVs (or compressor bypass valves) in the first place.

put it this way- the turbo doesn't really like having to deal with air suddenly try to rush backwards through it while it's spinning at ~100,000rpm

'dose' ftl

old wives tale?

ppl have explained this shit before, race cars with no bov take chatter every minute they are on the track and the turbo still is in good nic and there have been no proven negative effects.

I say, bov for ur chatter. no bov for your chatter, and stock bov for chatter afterwards when u get an FMIC and up the boost... either way u cant win if ur side by side with a cop at the lights and u need to take off normally...

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MBS206 Grand Master

MBS206

Posted
Posted

Run stock BOV with a boxed air filter.

I got asked just 20 mins ago after I took off from my cousins if I ran a BOV as they couldn't hear thing on gear shifting, only noise they could hear was me spooling up as I accelerated.

So keep foot of throttle (Just crack it, you can still accel quick enough like this) and shift really low in RPM range (2500RPM)

And a turbo is a uni directional fan basicaly, meaning air going backwards places NO force on the turbo at all!

And it was put on for emmisions reasons.

Double reading air on AFM = double fuel, but in reality you have single dose of air (Actually less) and a massive dump of fuel.

Also for the noise. No BOV = flutter. Such an awesome noise, but no matter how low in the revs you shift, you get it basically!

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R31Nismoid Grand Master

R31Nismoid

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old wives tale?

ppl have explained this shit before, race cars with no bov take chatter every minute they are on the track and the turbo still is in good nic and there have been no proven negative effects.

Why would race teams then pull turbos off after each race/meeting and change them? :teehee:

Race cars & roads cars = bad things to try and compare.

They are both built/tuned for a purpose in mind so generally dont form good examples.

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Turbo Dave Collaborator

Turbo Dave

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Posted

Ceramic turbine and Nylon plastic compressor!! You can block it off but i will stick with the stock BOV.

I blocked it the other day and it chattered everytime I backed off .The air isnt going back through the turbo is just cant go forwards while th turbo is still winding down from being on boost, so its creating a hammering affect against the compressor (Like turning off a tap to fast and you can hear it hammer back though the pipes).

If you want noise put a pod and airbox on, want stealth leave it alone!

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MBS206 Grand Master

MBS206

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Posted
Ceramic turbine and Nylon plastic compressor!! You can block it off but i will stick with the stock BOV.

I blocked it the other day and it chattered everytime I backed off .The air isnt going back through the turbo is just cant go forwards while th turbo is still winding down from being on boost, so its creating a hammering affect against the compressor (Like turning off a tap to fast and you can hear it hammer back though the pipes).

If you want noise put a pod and airbox on, want stealth leave it alone!

Not quite actually.

The noise IS the air physically going back through the turbo, although it's not the turbo making the noise.

Seeing how the fins are uni directional, backward flowing air WON'T slow the turbo down.

But what happens is you get a major pressure spike between turbo and throttle body, now the turbo is still pushing air in (With a certain force) When the air inside the piping between turbo and throttle creates a force that is greater then the force of air entering, it backward flows. But the problem now becomes the turbo is still supplying X-force, but the pressure inside is now less, so it grabs some of the air that just came back out, and slams it back in.

This happens over and over, so coming back out of your intake pipe (All the way back to the filter) you get a high pressure, low pressure, high pressure, low pressure (Relative to each other) and what does this give you? Well if you plot the pressures VS time, you'll have what looks like a sine wave. When air pressures go into a sine wave pattern with pressure changes, you have SOUND. It's not the hammering you get in your pipes at home.

Also, alot of race teams will pull a turbo off, inspect it, and throw it back on.

Why? Well they may have just done an endurance race, 6-24 hours. And 90% of that time the turbo is on full boost. That's like driving for 10 years on the street.

Also, car manufacturers build cars to last when you buy them, so if it's so bad not to run one, then why don't the CA18DET run them? Or a 1G-GTE? and I'm also pretty sure from what I've seen of a Porsche GT3, they don't run them either.

So if it's so damaging and bad to parts, why would a manuafacturer choose to do something that would make for warranty claims?

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rb180 Collaborator

rb180

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Posted

If the bov is plumbed back into the intake ( like the stock bov is ) then it is legal. Removing or blocking the bov will cause comp surge. Some believe this creates shaft play and can stuff the turbo. From all the things ive read about this i personally think it doesnt harm the turbo at all. Yes i am no expert but i have known many cars and read many stories of people running no bov for years and have taken the turbos off and nothing was wrong with it. This being the case i would do as others have said and leave the stock bov on with a boxed pod or airbox with high flow panel filter. Less cop hassles.

From what i once read car manufacturers put these plumbed back bov's on because when people would come to buy a new car, they wouldnt want it 'dosing' everywhere as it would possibly put the buyer off. When you go to buy a new car you want it to be smooth and quiet.

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STATUS Grand Master

STATUS

Posted
Posted (edited)

been running 2bar on the supra for 2 years with no issues, well over 400rwkw.

Cats car and my own cars (1.2.-1.5bar) have never run BOV's (response reasons) and we have never had a turbo fail

Edited by URAS
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