bosch blow off valves

[walkoau]

any one know where to get the bosch blow off valves from in sydney, what company?

also do you need an adaptor? what are peoples thoughts on them?

thanks.

[G0DF4Th3R]

i think Marlows or Supercheap have Bosch BOVs

[YEE-HAA]

You can try Coventry Auto Parts in Sydney. Bosch part number that they stock is 0 280 142 103.

[TTT]

they cost about $50 I think.

you will need an adapter plate to make it fit a skyline.

which cost about another $30 - $40.

what's wrong with your stock bov?

by the way, you do know that the bosch bov has to be PLUMBED back right?

[walkoau]

thanks for your help guys.

GTST

yeah i know it has to be plumbed back.

the BOV is for my friends gtst. he just bought it (the car) series 1 r33 and it has the standard bov, but it flutters????

do some of the stardard ones flutter? cause mine dont! anyway he just wants anormal one at a decent price so i surgested the bosch one.

[TTT]

if his car is making a fluttering sound, then I am going to suggest that the standard bov is stuck closed, someone has put a plate under it to seal it or it is blocked of somewhere, somehow..

take the bov off, and see if you can push the piston in yourself.

if you can, then the blockage is going to be somewhere else..

maybe there is a block in the bov return line..

check those out and see what you get.

[R31Heaven]

On the BOV line, my RB20 NICS don't have a BOV and I want to put a plumb back in, so the $40 Bosch would be fine for this. What are their limatations?

[TTT]

I think the boost limit is 15psi for the bosch bovs.

[R31Heaven]

Thats cool stock turbs on mine! and will not go past 12

[Cool Hand Luke]

Why do some BOV's flutter under low boost? I think it sounds unreal

[TTT]

bovs don't flutter.

they CAUSE the flutter.

when they don't open due to being set too tight, the air doesn't come out of the bov and has to escape the pipes back through the turbo where it came in.

but as it passes through the turbo which is still spinning, the air gets chopped up and if you have a pod filter so that you can hear the induction sound louder, you will hear the air getting chopped up as it goes back through the turbo.

that's the ft t t t t t t t t sound you hear that you call fluttering.

which is actually called "compressor surge".

[qikr33]

from what i have heard the flutter noise is bad,i have heard it can cause the compressor or exhaust wheel to snap off because of the force involved trying to act against the compressor??TRUE???

As for the bosh bov i would be going to a jap import parts place and getting second hand bov,The bosh is plastic and i think smaller (slightly) where as the factory skyline seems pretty durable

[walkoau]

GTST

thanks for the info. it was helpful. i have already checked the BOV return line and it hasnt been blocked off. so next i will take the bov off to check if its working or jamed shut.

[Cool Hand Luke]

Hey ive also heard blow off valves that flutter under high boost when they shut off. Sorta like a shivering sound, what causes that then? Not realy a f-t-t-t-t-t-t but a sh-i-o-o-o-o-o-w sound

An example would be the supra on exvitermini.com on the dyno. Under full load, then shuts off, you hear the bov opening but instead of a constant whistle, it makes a fluttering whistle. Also on fullboost if you listen to most of the cars on this site, they do the same, and no doubt run BOV's

[TTT]

cool hand luke.

the supra and most VL's and so on from the fullboost site don't run bovs.

they run huge turbos and huge intercoolers with large diameter pipe work and when they back off the throttle and there is no bov, the air goes back through the turbo and so on and makes a really loud shuddering sound. the sound is also amplified by the size of the turbo and pipe work.

hope that helps.

[Cool Hand Luke]

Ok, i agree with that. What im curious is what causes cars with good BOV's to make a BOV sound but instead of a continuous one, an intermidden sound, ala fluttering. Off to4r.com i have a video of a supra that did that, and was fitted with a hks ssq bov. I know its not important or anything like that, but if it makes a sound and i could have a choice, i'd rather have the one that i like better

[Roy]

Im going with the thinking of GTST on this one. I imagine some of the bigger hp cars making those noises run the ir BOVs very tight to ensure they are not leaking under boost. (????)

That said on one of the old Serious Performance Videos (was it the first one?) Lance Warrens 20B 929 made the sweetest noises, and it ran the Racing HKS BOV.

[TTT]

ok.

the standard bov on a skyline or 200sx or whatever, at idle, it is open and recirculating air.

when you start to accelerate, the bov closes and then releases immediately when you back off or change gears.

the aftermarket ones that vent to atmosphere, have to stay shit at idle.

so people have to tighten it up and they often tighten it up a little more "JUST TO BE SURE" (classic).

so when driving and say you boost up to 5 psi and change gears, the bov doesn't open when you release because..

1.) the bov is too tight.

2.) the aftermarket bov springs are tighter than stock.

3.) the bov piston is bigger/heavier and is not as quick to move as the stocky.

so what happens?, the air goes back through the turbo going f ch ch ch ch ch ch

or a similar sound (depends on turbo and so on)

however, say you had the same car boost to 8psi and change gears, the bov opens but really that much and the air gets out of the bov and goes "psshh" or "squeek" as the HKS SSQV one does, but then shuts the piston down quickly due to it's tightness, so you end up hearing a sound like

psshhht ch ch ch ch

to be honest with you, I love the sound of a 180sx or 200sx which has had the bov removed completely and the holes blocked off.

sounds like a pigeon or something..

but then again, my car came with a bov, it's not leaking, it's doing it's job and sounds ok and makes my car run better so I will continue using it..

does this all make sense or am I blabbering again?

[TTT]

you can also make a mod to the standard skyline bovs and the car comes on boost quicker and the bov sound changes a little..

instead of just a whooshh it sort of like a "ka tssss" sound..

I hate trying to "type" SOUNDS.

[Roy]

What makes you say the factory BOV is open at idle?

I dont think the engine vacuum would be suffecient to draw the BOV piston into the open position???