How Much Psi Can Stock R32/r33 Bov Handle

[RB SANDY]

I will go with cubes on the no bov very good on gear changers my car cherps 3rd and 4th now and with the horrible jerky driveability issue when changing gears at part throttle and low rev's and the odd stall none of that happend it stoped the stalling and the on the freeway before the bov was allways open a litle bit and also the sound (fluter) is much better. ps my boost is at 12psi

Edited November 23, 2006 by RB SANDY

[Cubes]

Interesting you have the same pain in the arse part throttle gear change issue.

I can't work it out as a mates VLT has no bov and that drives fine.

But the instantly on boost feel when grabbing that next gear feels so so sooooo much better.

[grigor]

That bleed hole may be 4mm dia at the gasket, but the orifice is only 0.5mm max inside.

The bleed or leak is very very slight and probably designed to smooth the transition of the BOV open/shut.

[RB SANDY]

yes you got to be very good with the clutch but it is not that bad at all

Edited November 23, 2006 by RB SANDY

[Cubes]

That bleed hole may be 4mm dia at the gasket, but the orifice is only 0.5mm max inside.

The bleed or leak is very very slight and probably designed to smooth the transition of the BOV open/shut.

I was able to blow quite a bit through mine. Definitely felt more than 0.5mm as 0.5mm is literally bugger all, based on when I've played around making my own bleeders in the past.

[SECURITY]

Top stuff. I will look in to it.

you'll need some sort of a reducer for the thing that the plumback pipe clamps onto. i did a dodgy and put a layer of the old pipe underneath the new one.

[limpus]

you'll need some sort of a reducer for the thing that the plumback pipe clamps onto. i did a dodgy and put a layer of the old pipe underneath the new one.

Same here...LOLZ!!!

[MBS206]

In theory it should handle any boost level I would have thought. The valve has the same pressure on both sides of it at all times when your on boost.

Only when shifting can it be a problem, and event then the down side is that the bov doesn't flow enough to allow it to stop a pressure spike back through the intake plumbing and reducing turbine speed.

Except that the fins are setup, so that if force is applied on one side, it'll spin and move air, if applied the other way, the air will flow through, but not turn the turbine...

Now think about it, air is being forced in, so it can easily blow back out, and put NO force on the turbo to slow it...

Some people are smart eh?

[sky30]

I ran up to 20 psi through my stock R32 BOV, but as cubes has mentioned, i also had the bleed blocked up with a grubscrew.

[dwayne293]

I blocked off the BOV on my 32 GTS-t just by making myself a new gasket similar to the mount one but without a hole in the middle, essentialy closing off the 'tee' into the inlet pipe.

Tried it just to see what it would do, definitely picks up quicker, but i don't have the same jerkiness issues as you, Cubes. Either that or I haven't noticed haha.

Until I find conclusive evidence that running no BOV causes turbo damage ( no I don't wish to start a war or we might as well call this forum ns.com) I will continue running it this way.

I ran my R30 with no BOV day in day out at around 17psi boost for ages, it did over 200,000km and the turbo lasted longer than the piston rings, so meh

my 2 cents anyway

Dwayne

[dwayne293]

Knew I took a pic of my BOV block off gasket (for want of a better term)

Apologies for inage size and quality...

Oh yeah don't bother clicking on it to see it larger, AAAAAAHHHH PIXELS!!!

Dodgy camera phones

Edited November 29, 2006 by PHOTON-XL

[Cubes]

I put my issue down to the motor boosting so early.

If I change up at 3000rpm+ as I used to with the rb20det it feels fine.

[buggor34]

Photon-XL does not having a bov create compressor surge? With the bov blocked off does it make

the flutter noise? I am just interested as its something i would like to try. To do it do you just block

off the return pipe, make a new gasket to seal the hole on the intake & how do you block off the

vacuum line? Other than this idea does anyone reccomend a specific bov? because the standard

one sounds pretty annoying after a while. thanks

[Rolls]

Interesting you have the same pain in the arse part throttle gear change issue.

I can't work it out as a mates VLT has no bov and that drives fine.

But the instantly on boost feel when grabbing that next gear feels so so sooooo much better.

I recently got my bov (silly hks loud one) removed from my HR31 and I have experience no issues except it being much nicer on gear changes as it does not have to build up boost again, it also doesn't backfire as often when changing gears.

Can someone answer me this, I dont really understand how a plumback works, Im assuming it plumbs the air from near the TB back into the compressor. What I dont understand is wouldn't the pressure be the same and the air would take the lowest pressure path, out the air filter? I know this clearly isn't what happens, but could someone explain why it is so.

[b0neR]

Probably because the compressor is creating a vacuum like situation on the intake side (it's still spinning), hence the air doesn't necessarily go out the air filter. That's just my thinking anyway.

Theoretically not having a BOV should be bad if the airflow is going back through the compressor because it will slow it down, bad for getting back on boost (driveability) and bad for the turbo because of extra stress on the shafts/bearings or whatever. In practice though it seems that maybe the vacuum created in the plenum once you've closed the throttle may make the air suspend or at least force its way towards the plenum, which is what you guys have experienced. Mind you this is taking into consideration quick/high rev changes. The part-throttle/low rev changing may change the way some of the airflow behaves given compressor speed etc.

[Cubes]

Theoretically not having a BOV should be bad if the airflow is going back through the compressor because it will slow it down, bad for getting back on boost (driveability) and bad for the turbo because of extra stress on the shafts/bearings or whatever. In practice though it seems that maybe the vacuum created in the plenum once you've closed the throttle may make the air suspend or at least force its way towards the plenum, which is what you guys have experienced. Mind you this is taking into consideration quick/high rev changes. The part-throttle/low rev changing may change the way some of the airflow behaves given compressor speed etc.

That sounds good in theory but I think the turbo having to spin up and fill the ic piping and fmic negates any benefits of the compressor being slowed slightly, so its one theory against the other and in practice the no bov and not having to fill the ic piping and fmic theory wins.

Give it a shot the no bov really will spin you out how much quicker it spools and is on boost again after a gear change.

[Rolls]

Probably because the compressor is creating a vacuum like situation on the intake side (it's still spinning), hence the air doesn't necessarily go out the air filter. That's just my thinking anyway.

Hmm after thinking about it for a while I think this is what happens, however as the compressor loses speed the vacuum would lessen and then I guess the pressure would eventually equalise by going out the air filter.

[RaseR]

I had BOV leakage issues in my old R32 when I decided to run up to 1.1bar...Blocking up the recirc hole didn't really do much IMO, I've read heaps articles/forum topics about this very BOV on this very topic, because I was so interested at the time...and still am now!

I discovered the function of the recirc hole (in very non-technical terms) is to allow the BOV to open as fast as possible, even at very low boost (and near-boost vacuum levels)...hence the loss of down-low driveability, slight surging & flutter exhibited when blocking it up....with not much benefit - the BOV is opening slowly now and as such allowing some air to reverse back through the turbo & AFM...causing incorrect readings which are then fed back to the ECU.

That being said, I took the idea further and made up a plate to go underneath the BOV that had a hole around 1cm diameter in the middle, essentially making the BOV even less able to flow air...This had an enormous effect, and is where I picked up the extra 1 psi of boost and the much increased response after gear changes...From this experiment I can only surmise that the BOV was leaking quite severely through its seating (the car must've done around 170-180,000k's, many of which at higher then standard boost)...Side effects were that the car was way more inclined to surge on throttle lifts, had the occasional near-stall when returning to idle and air reversion (flutter) on every single gear change when on boost, but power was up and it felt much more lively...Conclusion - a better BOV was what I really needed ...If I wanted to keep stock-like driveability as well as keep the increase in response.

(newer stock or GTR BOV retrofit was what I was thinking at the time)

Edited November 30, 2006 by RaseR

[Munna1]

Ive tried blocking that hole too. The car came on to boost quicker but I had surge issues so I unblocked it again and drivability was much better.

cheers

[R31Nismoid]

I will go with cubes on the no bov very good on gear changers my car cherps 3rd and 4th

Thats because you cant change gears correctly, or you have poor tyre/suspension setup.

"chirping" on gear change has absolutely nothing to do with/without having a BOV.

Give it a shot the no bov really will spin you out how much quicker it spools and is on boost again after a gear change.

i found the opposite while using the stock ECU, NO BOV caused no end of issues (RB25) with stalling and throttle response.

GTR BOV went on, problem went away

But stalling etc is largely due to driving style as your already aware im sure