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Dale Holan
TryHard
Alberta
2.5 GTT L

Posts: 151
Reg: 06-2007

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Saturday, September 29, 2007 - 08:35 am, by:  Dale Holan (Xtrax) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I have an aftermarket HKS Super Blow Off Valve something doesn't seem to be running right in my mind. What RPM/boost level should my BOV blow off? Can it be adjusted? It sounds like I'm getting a compressor surge at lower RPMS (3000 to say 4500) but It'll blow when I'm well over 5000. Also I'm unsure if It is hooked up correctly. It seems to have 2 lines going in but they come from the same source.

Any input would help.
Grant Rowan
TryHard
QLD
jzz30 TT

Posts: 103
Reg: 02-2006

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Saturday, September 29, 2007 - 09:15 am, by:  Grant Rowan (Booster13psi) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I have a HKS SSQ Bov. I have noticed that it blows audibly at about 5psi and above. The SSQ should have an adjustment nut on the back of it. I have never touched mine so I don't know what adjustment increments can be made.
Justin Camilleri
DieHard
QLD
Had a 85 MZ10, 92 TT, Now 91 TT

Posts: 583
Reg: 07-2005

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Saturday, September 29, 2007 - 10:15 am, by:  Justin Camilleri (Just) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Maybe adjust the tension of the spring??
Dale Holan
TryHard
Alberta
2.5 GTT L

Posts: 152
Reg: 06-2007

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Sunday, September 30, 2007 - 03:25 am, by:  Dale Holan (Xtrax) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I'm not too sure if mine has an adjustment screw or how to adjust the tension spring. I'll take a couple photos, maybe you can suggest how to adjust it.
thanks for your help.
Daniel Clarke
Goo Roo
NSW
TT 2.5L 6 cylinder

Posts: 2362
Reg: 03-2006

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Sunday, September 30, 2007 - 02:49 pm, by:  Daniel Clarke (Dieseltrain) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Do you have a PoD filter?

If so, then you will get a " flutter" coming from the Pod. This is common and most TT's will do this evenw ith an after market blow off valve fitted.
Scotty Wheeler
Tinkerer
TAS
Soarer TT (Converted To Single)

Posts: 36
Reg: 06-2006

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Sunday, September 30, 2007 - 06:17 pm, by:  Scotty Wheeler (Typhus_sw) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

my guess would be that you still have your factory plumb back, which is found at the end of your plenum, which is the same as a bov only when it opens it lets the pressure out of the plenum and is plumbed back in just after your air filter.
Hence the flutter daniel is talking about is the air from the plumb back flowing out your air filter. Your bov won't be as audible because the majority of your air pressure is goin through your plumb back, if you adjust your bov so the spring is softer it will be more audible..
Probably help more if i could explain it a bit better but thats the best i can do for now, Good luck with it.
Charlie Ters
Tinkerer
nsw
TT

Posts: 65
Reg: 01-2007

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Sunday, September 30, 2007 - 09:30 pm, by:  Charlie Ters (Ul05st) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

what he means is that at around 0psi, his blow off valve isnt going WOOSSHH loudly .... (maybe very lowly)...well the truth is, no blow of valve does, nissans for example, will always have major fluttering under 6psi, and BOV's are made to vent EXCESS psi..... anything under 'excess' (which is mostly spring related) will not open a bov.... simple, remember your HKS blow off valve is made to probably support 600hp++, you cant expect around 300hp to let it off at its full potential using ct-12's @ 0-6 psi @ 2900rpm etc.... well... thats my theory if a BOV doesnt open at 7psi+....then something is wrong (but remember with the the soarers, it aint open for too long)....
Steven Anderson
TryHard
NSW
UZZ31 Manual

Posts: 149
Reg: 05-2006

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Wednesday, October 03, 2007 - 09:18 pm, by:  Steven Anderson (Cusscuss) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Had to think through this one a couple of times.

BOV's use springs in them to keep them closed when idle and under boost as there is equal pressure on both sides.

It when there is a pressure difference ie, throttle closed and vacuum in the plenum but boost in the pipes it will force it open.

Sometimes vacuum is not enough to overcome the spring e.g. low revs so the BOV will not open. This is why some of them have adjustable springs in them. Its normal behavior.

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