Stock Bov Leak? Or Just My Imagination?

[WazR32GTSt]

so here's the story..

most of the time when i accelerate, i have very loud inducion noises. in fact, my brother has a pod on his 300zxTT and a friend of mine has a pod on his tx5 turbo and neither are even half as loud as mine

BUT... my setup is only the standard airbox (with some cold air intake pipes) with a high-flow fitler

and on full load on the dyno it runs about 10.5:1 AFR

(there doesn't seem to be an air leak)

the thing is... sometimes (like 5% of the time), its not as loud as it normally is...

do you think that my stock bov may not be holding boost well (i'm running 12psi) or is it just a figment of my imagination because i want a quick-fix for the fact that i nead an ECU eprom?

cheers,

Warren

PS car is 1992 r32 gtst with 140000kms

[jezzerrr]

I had the same thing on mine. installed an aftermarket bov and it's still just as noisy, but at least i have the peace of mind knowing that my bov isn't leaking. that can lead to very bad things if you wind the boost up. the quick way to diagnose it would be to slip a thin plate under the bov, blocking it off entirely and seeing if you have the same noise. you can run wihout a bov, but there's contention between whether this causes long term damage to your turbo or not. with 140K on the clock i'd say it would be a fairly safr bet the spring in the stock bov is worn out.

Edited February 27, 2006 by jezzerrr

[TTT]

stock bov is designed to CONSTANTLY have some air circulating.

take it off.

look at the bottom of it.

you will see a small hole next to the bov piston.

you can block this hole off with a flat headed wood screw.

this has been covered many times and there is even a thread on here with pics on how to do it etc...

block it off, stick it all back on and go for a drive.

you will notice a few things.

1.) car will come on boost noticbly quicker.

2.) bov release sound is different (if you have FMIC, you may get some flutter, if you have stock cooler, it makes a louder psssh sound)

3.) spooling sound is less especially during low boost/cruising where the un modified bov would just constantly circulate the air making a constant shhhhhhhhhhhhhhh sound..

[paulr33]

i am curious how it makes the car come on boost quicker ?

[justin911]

oooo sounds familiar to wat i was saying doesnt it paul

[TTT]

well there is no circulation of air when you jump on the accelerator.

the hole is there to make boost come on smoothly. and make the transition between on throttle and off throttle smoother.

you block it off and as soon as you are on the accelerator, it begins to pull harder and build boost quicker as it is comepltely sealed instead of circulating air.

same as if you got an aftermarket bov.

they are good in that you can build boost quicker than factory bov without this mod.

try it.. you've got nothing to lose.

[paulr33]

i still dont believe it

[justin911]

why dont u try it then ?

[TTT]

hahahaha.

well there are 2 ways I can make you a believer.. one is probably easier than the other.

1.) you catch a plane to sydney, pay about $50 for cab to my house.

I'll take the bov off, take the screw out of it, then you take it for a spin for 5 minutes or so, then I'll put it back on and you can drive it around again..

or

2.) as above, just try it.

how can you say it doesn't work or don't believe it if you havent done it?

Ignorant is the word I'm looking for here..

[WazR32GTSt]

thanks GTST... but you see i have lready blocked off the bypass hole many years ago (and yes there was a change in the acceleration noise once i did this...)

any other ideas?

PS let's keep this thread on the topic and not stray off onto the bov block-off mod which has been covered many a time! thanks!

[TTT]

ok..

the only other thing I can think of is the gasket between turbo and manifold.

I say it only because my VR4 was really loud on boost (ONCE WARM).

when it heated up, the boost/air leak sound was louder and louder.

so maybe something to look at.

I'm all out of ideas there mate.

[WazR32GTSt]

no worries.. thanks for your help mate!

i'm still thinking might try a second-hand r33 bov or something? worth a try or not?

[R32FOURDOOR]

Dude ive got the exact problem. In my R32 you could hear it sucking like jesus. when i put in a pod it got louder!!

I blocked off the bov and this didnt fix it, in fact the sucking noise was even louder doing this(bad move)

My car is running stock boost and it does this.

Do you think the turbos stuffed?

Maybe it could be the gasket like what GTST said? Did it fix the problem on ur VR4????

cheers

[RaseR]

Hi Warren,

When I had my R32 I had the same thing, I also suspected the BOV was leaking, I firstly blocked off the little hole with a self tapping screw...this did make a slight difference, the BOV definitely opened slower but I still felt it opened and sustained far too early, it also made the car jerkier to drive with little advantage to justify the mod.

So I went to the next step - instead of blocking it off entirely, I made up a thin aluminium plate with a 12mm hole in the middle that sits directly underneath the BOV (like a gasket), reducing the amount of air it can potentially flow/leak, I immediately noticed the difference, it seemed to pull harder through gear changes (particularly 1st to 2nd).....only problem was it obviously couldn't work as effectively, hence I got a bit of the flutter at higher boost, I actually prefered this to the wheezy. sustained sound of the stock bov through the pod, so I left it.....No stalling problems either, as it still flowed adequately at low boost/rpm....In hindsight, I'd prefer to install a higher performing adjustable plumb-back BOV, but my mod worked alright as a quick-fix........that I stuck with for 40,000kms!

[WazR32GTSt]

hmmm so this isn't a one-off then...

maybe the rb20 bov is different to the rb25 bov (ie inferior)?

no one has this problem with an R33?

is the rb25 bov a direct fit to the rb20 bov location?

Waz.

[RaseR]

Hey again,

The R33 and R32 BOV seem identical (I've got an R33 now) on the exterior...I reckon the major difference is that in most instances they're newer and less prone to leaking......that being said I do see/hear heaps of R33's driving past making similar noises to my R32 before I did this particular mod......they're meant to open up pretty early (ie. before the car even begins to make positive boost).

Edited February 27, 2006 by RaseR

[predator]

yeah, they swap across.. I guess that if you put on an R33 one, there is a better chance the spring will be slightly fresher than the R32 one.

Otherwise, with the two BOV I swapped across, I noticed stuff all difference.

[TTT]

the bovs are the same.

both Mitsubishi parts.

actually, same bov on the vr4.

you wanna know what the vr4 boys do to their bovs to hold more boost?

http://members.shaw.ca/costall/1000Q/answe...atisacrushedBOV

fyi - 1g = first generation.. vr4 here, talon in states etc..

[RaseR]

hahaha, let me guess....they crush it in vice? Yep, I remember this back from when I was researching ways to fix the 1G bov, here's some other interesting modifications you can do to it to make it hold more boost:

http://www.thedodgegarage.com/turbo_bov_mod.html

http://www.dejonpowerhouse.com/

(click DSM, then BOV-misc-tools, scroll down to the bottom of the page - check the test data, they got the modded BOV to hold 50psi!!!!)