I had the Greddy Type-S BOV installed on my kit and picked it up last night.....finally....it took forever. I still hear that sound if anyone remembers my post of the turbos spooling down.... kinda like a phaser sound....vwhooo... , but then i hear a high pitched whistle...the BOV letting out the air. I just want to know if I should still have that sound of air going back to the turbos...? I have my BOV installed between the IC and MAF just like GQ. I thought a BOV should sound like what air coming out of a compressor sounds like... PSHHHHHHHHH.. and really loud.. not a little whistle... but i have no idea. Just worried about the original noise still there.

 

Sounds like it's adjusted too tight. I'd just check the screw on the top. It should be set as soft as possible without it sucking in air when your idling.
Gary

 

how would i figure out how to set that? And how would I adjust it...just turn a screw...? How would I know it was sucking in air? Thanks 7eleven!

 

if you still hear that phaser sound, perhaps your BOV is on too tight... turn the **** CCW to loosen the valve.. but too loose and it will blow off easier and there might be a possibility of it being open during idle, causing stall. the bov should not allow the sucking of air into the tube- it is activated via vaccum lines, and opens up when you let off the throttle.

the type S is a very high pitched whistle/chirp. not a PSSSSSSSShhhhh noise.. thats only in cartoons. (j/k) my HKS is a loud "Skiii" noise during high boost and a "Chee-Ski" at lower boost blow offs.


taken from blowoffvalves.com
"The BOV has an adjusting screw on the top. Use a 10MM wrench to loosen the nut that keeps the screw in place. Then use a 3MM allen key to turn the screw back and forth. Tighten the 10MM nut (snug but not too tight) when you are finished. First, do a rev test with the BOV if you will vent to air. After a few aggressive revs, the valve should close quickly on it's own power. If it does not close or takes too long, then the valve is set too softly. Then do a test drive to listen and be sure that you are getting proper pressure release. If you boost highly, you may want to consider a Type R Greddy instead."

 

exactly. Loosen it up a couple of turns.....test.....repeat as necessary to achieve optimal "ppppssssssshhhhhhhhhhh".

Also note....at lower boost and lower RPM operation, the Greddy type S kinda sounds like a wheez.....not really a psssshhhhh sound...nothing to worry about. But regardless...on the Greddy, when properly set....you should not here the chachacha of compressor surge at all.

Oh, and if the BOV is too loose, your car is not going to stall....becuase any extra air sucked in will still be measured by the MAF. It's hard to tell if the BOV is too loose. The biggest indicator of a too-loose valve is boost leak. So if you are boosting 5psi, and then you see the boost drop a bit after adjustment....then your valve is a bit too loose.

 

Thanks Cheston and GQ.... im sure this will help others out if they decide to change boost and get problems...

I hope I dont ask too many questions.... I like to look here first since its already been done on the Z rather than looking in manuals and searching for hours sometimes... Everyone here is a great help.

 

I'm working on it now..... It sounds much better... thanks guys! I do still have the phaser sound i was describing.... although it only lasts about 1/2 a second now and the BOV noise is much louder and prolonged... I have the adjustment screw out pretty much as far as it will go without it falling off... I have not lost any boost though... I'm at .4 bar... Does anyone else have that noise at all like me for a second before the BOV kicks in...or does everyone else hear nothing but a whistle?

 

the louder the BOV is.. the more air is going through the "horn"
if that screw is about to fall out, then its WAY loose.. shouldnt be like that- shouldnt need to be like that-

did you hook up the bottom Vaccum hose to it? or just the top?

 

I'm not sure.... I didn't do the install. I cant see where the hoses are attached really? It looks like there is only one hose running along the top when i open the hood since i got the car back.... looks like the hose in the kit... im guessing... I did not see another hose in the kit... you need both im guessing?

It's sill going through the VROOM then the WOOWOO then finally the new high pitched VREEEEEE sound. I should write BATMAN comic books.

If i have to do it myself....where should the other hoses go....or should I go back to the mech.

 

the second hose for the Type S is to for low boost applications.. probably what you need since you are hearding WooWOoOWoo compressor surge noises... but its for the turbo pressure line.. you have to run a line from the positive pressure side of the turbo. i think its the line to the waste gate actuator... (?) basically it assists in the opening/ closing of the valve...

 

still not sure what you said chebosto.... I took off the line from the top and put it on the bottom... now no noise is coming out at all....just a compressor surge..... I might not have understood correctly what you said....

Where should the hose be.....and should I hear any kind of compressor surge.....? I noticed that the bolt was too loose when i set it the original way...so i set it back and there was barely any noise... I cant figure out what the problem is...

 

Brusch....put that vaccum line back where it was. My installer only attached one vaccum line. Honestly, I cant even see a second nipple...so not sure. Anyways, just reconnect that hose. I'll have to check it again closely to determine if there is actually two lines connected.

Incidently, I was experimenting today with loosening the BOV to create MAXIMUM pssssshh effect. So I basically completely loosened it until the bolt almost fell off. Then I tightened it about 2 turns, and screwed down the lock nut. Took it for a quick spin. MAAASSSSIVE sound....even on decel at vaccumm... Holy crap....I had every dog barking at me on my street...and casual onlookers were ducking for cover!

There was no boost leak...still boosting 7psi, but the spool up was signficantlyi slower. I think that under vaccum, but on the throttle..there is some air leaking from the BOV....the car kinda felt like it sputtered a bit....felt like crap.

So I tightened it about 3 more turns, and now the sound is tight and effective.....I'm happy with the way it sounds now...it was just too damn loud at full soft.