ALWAYS wondered what makes them Sound like this (I run a Forge so don't give me crap please just Curious):

The Main one I've wondered is it sounds like The Spring on the Unit is barley tightened down and it "psh spee spee spee " and you can actually hear it Closing type bypass.
EXAMPLE: http://www.norris-designs.co.uk/swb-green-evo.wmv

*remove the ",0:32" if video dosen't play correctly - Its at the very end when it comes Pulling up.*

I've heard it on NIssan's (Yoshio Factory S15's) the Norris EVO,Tons of cars.

WTF kind of BOV makes that sound?

PS: and theres the Supra one that I think everyones heard - sounds kind of like a Turkey Gobbler...only really heard that sound on Supra's or 2JZ IS300's

IN GENERAL thay have diffent sounds but the Flutter? What makes them flutter i guess is my Main question.

 

High boost applications usually run hks ssq bov b/c it doesn't leak at 30+ psi b/c of the design....search and you shall find

 

So it comes down to the POWER and boost levels that make that sound in conjunction w/ the BOV unit.

OK thats what I was figuring because that sound is normally found on High boosted/HP cars.

Thank you sir

 

Correct me if I'm wrong, but I believe the fluttering you hear in the video is compressor surge brought on by a BOV that has a very stiff spring (probably an HKS SSQV).

 

HKS I have it. Coming off boost partial throttle.

 

Not necessarily. The HKS SSQV has different inserts that make different noises. One them makes a repeated "chewchewchew" noise (I actually laughed typing that) Although the HKS SSQV is notorious on this board for compressor surge, that noise isn't necessarily indicative of it because that is the way it sounds with that specific insert. The way you know it is surge is when the car bucks a bit, which requires you to be driving or in the car.

 

the flutter is and can be due to many differet things. it is most prevalent on valves that use more than one assist nipple, that said it can and does happen on any valve.

reason one: at light load low boost conditions you get a partial purge at which the pressure of the vacuum produced matches that of a harmonic frequency in the valve assembly (the spring or springS) and this causes a light flutter. happens a lot in stock valves.

can happen if you tap the lower intercooler pipe area for the boost source, this may happen due to boost inconsistencies and other such fluctuatinos due to pipes leaking causing the turbo to spitter around cuz it's working hard and then letting go a lil tehn getting forced to work hard again. dynoflash and buschur have claimed this type of flutter in many cars they've seen. a solution for this is to tap a more consistent boost line, but this of course also does not reference the most EXACT boost.

another reason is vacuum line size. apparently someone i know did a lil test between cars. swapped a greddy type s into twi different cars running two different size vac hoses and one produced flutter and the other didnt'.

i get flutter in my 1g, i didn't get it before i started using hte dejon tools leak stop, but once i started using it i got the flutter. this was reported in some dsm applications too. several reasons that have already been stated could account for this, one being line size two being the resonating frequency of the spring system however the spring system now includes all the pnumatic assisting that goes on which them makes for more modes of fluttering.

the hks valve is prone to some fluttering as it uses two size valves and two size springs bringing on more modes in which fluttering can take place

also different valves may be more prone to fluttering becuase of their valve size or spring size or valve spring size ratio that brings on certain mods of flutter.

btw if you searched i've said this before.

 

I love that sound so ******* much...

 

30 lbs on boost on a HKS SSQ bov from what im hearing from alot of people it cant even hold past 20 lbs of boost.. dunno.. i really want to get that bov but alot of people are telling not too that it has alot of problems

 

cant watch the video cuz im at work but the way you describe it sounds a lot like a fluttering external wastegate. It sounds so good on supras....... thats what i think it sounds like ill watch the vid when i get home and let ya know for sure lol

PJ

 

You have been misinformed as to the HKS's ability to hold boost. It holds boost VERY well. 60+ lbs. There is a member here that is testing various BOV's and has found the HKS SSQ to hold the most.

It's drivability is what is in question. I have it and you have to be either on the throttle or off. No in between.

Back OT, High boost apps. with various BOV's (Tial, Forge, etc..) seem to replicate the sounds you describe.

 

The HKS SSQV can hold just about anything you can throw at it because it uses the boost pressure to hold the valve closed. Driveability on the Evo is a no no, unless of course you go MAP.