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Flutter noise - How?!?!?

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drifto Collaborator

drifto

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A turbo go bang as as Denton R33 put it, after constant abuse by lifting off full throttle at full boost often and overboosting. Both ways will vary between turbos in how long or when it will make the turbo go bang. It want happen because yours makes a flutter sound which normal and will be heard better when you remove the stock airbox and filter set up. Adding a front mount will change the sound in terms of duration, frequeancy and volume, but no the fact it happens or not.

My brother had a stock black top rb20 in his 31 4 door and a APEX GT Spec front mount. It had the most awsome and loud flutter. He ran 14psi with the stock ceramic turbo and never hurt it.

My 32 has a blitz BOV and because of the spring tension being higher than a stock silver top blow off valve, it doesn't open unless there is a substantial pressure increase caused by a sudden lift off under high boost. Which is when you won't it to go PERCHEW not flutter.

If you drive around normally and change gears during the spool up phase and not on boost, it makes a nice tight flutter unlike my brothers one which was loud, long and slow sounding.

A weak setting in any BOV will cause the BOV to open under moderate pressure levels giving you a single PERCHEW not the flutter maybe before you are on boost. No good for spooling up which will make the car feel laggy.

DCIEVE Mentor

DCIEVE

Posted
Posted

just set up your bov fairly tight so it only opens when your backing off over say 8psi, then you get the flutter when your taking it easy and the benefits of the bov when hard at it.

to change the sound just back of the throttle at different speeds, too easy

[R31][Silhouette] Contributor

[R31][Silhouette]

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Keep it the way it is.

They come plumb-back for a reason  :rofl:

Your car will probably stall and play up if you remove the bov.

Well last night I did what sky-rkt said and took off the bov and just placed an alluminium cut out over the hole and then put the bov back over the top and screwed it all back together, and now... It flutters! : ) It hasn't effected the way the car drives at all! Still boosts the same, revs the same! everythings the same - just a nice flutter now - that's all!

Cheers

[R31][Silhouette] Contributor

[R31][Silhouette]

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it'll be slower on the gear changes as the pressure aint going out where its meant too = hinderance in performance

Yeh maybe so - but it's not that bad that I can even feel the difference - still pulls the same through the gear changes, maybe cause it's not boosted there isn't that much pressure to get out? I dunno feels the same to me

[R31][Silhouette] Contributor

[R31][Silhouette]

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do you think it would make a diff if you cover up half or more of the hole? it would couse a bit more back pressure yet still make use of the bov???

I reckon you'll get a bit of both! but I cant imagine the flutter being all that loud?

Only one way to find out I guess..

aKTiVE Collaborator

aKTiVE

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i have dabbled in this area a little bit... how to get the 'sickest cooler dose'. There is a constant debate as to whether removing all bovs will damage/reduce the life of your turbo... but basically its up to the owner whether they think its wise or not...

Anyway, on all of my cars that were turbo charged, it became obvious to me the piping/cooler size/turbo/air filter would depend on the sound of the 'flutter'.

Decent sized cooler piping, aftermarket fmic and a pod filter will amplify the sound.... but the ONE mod to me that made the sound very loud, was removing the standard plastic piping from the turbo to the airfilter/pod to a steel pipe...

I usually have bovs on my car, but they are tightened up to the sh1thouse. So 10psi and under it will flutter, and then when you release the throttle on full boost, it will flutter and bov simultaneously... sounds great =)

  • 2 weeks later...

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