Whats Changed?!

[Raven33]

Hi everyone

My pride and joy series 1 R33 gts-t has been a bit sick.

So I've been messing around with the intake pipes a lot since I had to send my KKR 430 turbo away for a new core.

when I took the turbo off I reverted a couple of things back to stock - turbosmart plumb-back bov and pod filter came off, and original items went back on.

However since I refitted the turbo I've been getting this idle wave I've tried heaps of stuff to fix it to no avail - I even got an R34GTT SMIC

- so I figured it must be something todo with the stock bov, so I put on the turbosmart, plumb it back the same way I had when I first installed it and slapped the pod filter back on, for now - just because it's easier to work with.

The sound change from standard to this setup above was originally just a louder induction sound and the blow-off "PSSSSHHHHTT"

Now the exact same setup - the only thing changed is new turbo core - and it goes "voot voot voot"

and I'm not sure if I it's just me - but I swear after a gear change the car seemed really gutless for a sec - not just turbo-lag gutless - but really flat, till it hit boost and it was fine.

Does this sort of thing sound familiar to anyone?

would the new core be the cause of the sound change - I would think it's something else... perhaps the same something causing the pissy idle hunting which is still happening - no differently.

Ultimately my goal is to fix the idle - I'm just curious about this new blow-off sound.

Thanks for reading and any questions or suggestions swing me a pm or post on here - I'll have the page open for a few days.

~Raven.

[paulr33]

the voot voot voot is compressor surge that occurs when using no bov, or a spring that is too tight

the bov does not open (or the car doesn't have one) and the result is the pressure in the pipework spies through the roof when the throttle body closes on gearchange

the end result is presssure at the compressor wheel exceeds what it can flow, the compressor wheel surges and stalls and the result is the mid air collision voot voot voot noise

mangled bov

incorrect bov

no bov

are your causes

fix these and the bov will open correctly when pressure spikes and vent the excess pressure to the front of the compressor wheel instead of trapping it in

[Raven33]

*begins removing bov*

is there anything i can do to make sure it's working as it should?

+edit: the resistance on the turbosmart on it's softest setting feels the same as the stock bov by hand - this is the setting i had it at

Edited October 1, 2010 by Raven33

[ltcree]

Check your vac lines etc are all correctly installed. If you blip the throttle up you should see the bov open slightly on decel. Have you changed the 'hardness' of the bov because that will change the noise of it.

[Raven33]

I just put the stock bov back on - seeing as putting the other one on didn't change the idle problem.

i'll take it for a burl tomorrow, see how it goes.

[Raven33]

well I've compared the stock bov to the turbosmart one - they both seem to be working in the same fashion as far as I can tell.

driving the car with the sotck bov and pod filter the car makes the normal pssshht again.

The only theory I have is - when I was originally running the turbosmart bov I was running higher boost than I am now (still being safe running at 7psi since new core)

perhaps the lower boost now + maybe a slightly harder setting on the bov itself was enough to stop the pressure being able to open the bov

anyone able to confirm if this could be the case ?

still getting the slight idle wave, though it does seem to be less today - hoping it's just a bad seal on one of the intake pipes somewhere.

[ltcree]

well I've compared the stock bov to the turbosmart one - they both seem to be working in the same fashion as far as I can tell.

driving the car with the sotck bov and pod filter the car makes the normal pssshht again.

The only theory I have is - when I was originally running the turbosmart bov I was running higher boost than I am now (still being safe running at 7psi since new core)

perhaps the lower boost now + maybe a slightly harder setting on the bov itself was enough to stop the pressure being able to open the bov

anyone able to confirm if this could be the case ?

still getting the slight idle wave, though it does seem to be less today - hoping it's just a bad seal on one of the intake pipes somewhere.

That sounds right, mine at low boost (under probably 10psi) gets a bit of flutter because of the hardness of the bov.