Blow off valves fact or fiction

[R33_Series2Lover]

Hey all ive heard that if a fluttering noise is heard from your blow off valve that it is actually a bad thing. Because as i know of the HKS super sequential has that fluttering noise and also ive heard the GFB Hybrid also has the fluttering noise at low rpms. Ive heard a couple of people say that if the blow off valve is fluttering it is not a good thing. What do you guys say??

[strutto]

I say do a search

[cameron]

Somtimes the BOV does flutter if the screw is loose (HKS SSQV) and this is fine, but if its tight and its fluttering thats the pressure going back through the turbo which is not good for it after a while.

other than that

[Doctor]

Its not your BOV fluttering its air boucing off your butterfly and going back out through your turbo and getting chopped by the turbine blades. Most liekely cause is BOV too tight.

Do a search on "reversion" and it will detail the ins and outs of it all.

Doc

[dangerous_daveo]

Could also be the stock-o wastegate? No?

[R31 POWER]

Could also be the stock-o wastegate?  No?

I know the noise you mean and I have only ever heard it come from a subby wagon fitted with a EJ20 (what ever it is) from a rex and it had a spring on the waste gate to hold more boost.

[Jimbo2000]

the ssqv flutters at low revs no matter where the screw is, loose/middle/tight

[dangerous_daveo]

I know the noise you mean and I have only ever heard it come from a subby wagon fitted with a EJ20 (what ever it is) from a rex and it had a spring on the waste gate to hold more boost.

I get it on my car quite often. And I know its different to the air going back thru the turbo as I used to have my BOV blocked off.

[Doctor]

Jimbo thats becuase HKS make there springs really tight. I had the same prob with mine. Anything tighter than stock will flutter thats why nissan (sorry Mitsubishi) made stock BOV like that so it air would not reverse. The reason why aftermarket BOV's are tighter is so it stops boost leak.

[cameron]

I've noticed that when the HKS SSQV bov is tighten fully. When under full boost if you let the accelerator off slowly it doesnt go off (goes back through turbo) but if you let the accelerator off fast it will. Its queit handy, If you see the cops at the last minute.

As Jimbo2000 said it does flutter fully tighten at low rpm when turbo is making boost.

[someonestolecc]

is that a case of the bov being too highly-rated for the application?

ie the turbo isn't boosted enough (and the engine isn't built to support the higher boost) so the bov is not letting enough air out (and defeating the point of having a bov/recirculator to protect the engine).

if the turbo had enough boost it would always open even at low rpm and allow for air to come out.. pssshtt

is that right or did i miss the point?

[abcent]

my car makes the "flutter" noise, hi-flow turbo an running stock (mitsubishi) BOV, so does that mean my stock BOV is tighter than most stock BOV's?? Noise only on higher boost, so i'm thinking its because the stock BOV isnt up to the job...not tight enough.

Be interesting to see peoples replies, as first mentioned, I've also heard some people say air pasing back through the turbo = not good, others say that its fine?

[Doctor]

Not really a matter of "being too highly rated for the application", its got to do with trade off. You cant have a loose spring and expect it to hold boost in a high boost environment whence the reason they are fairly tight.

[R33_Series2Lover]

Sooooooooo with all these problems its like saying putting on a Blow off valve to your skyline is a bad risk. So what Blow of valve is the best for a skyline so it doesnt run rich and back fire and have ecu error messages. I was thinking of heading off this weekend and having either a GFB Hybrid or Turbosmart Dual Port Blow off valve fitted as they vent back into the engine and out to the atmosphere. Is one better than the other or do they both do the same thing and wont have any problems such as fluttering and the other probs mentioned above. I Just want a cool PSSSHT sound without f_ _king up my car. Any suggestions would be highly appreciated.

[cameron]

I don't think a bov will cause a rich mixture more to do with the ecu, or aftermarket fuel pump. - SAFC ll will fix this problem.

I would recomend HKS SSQV as their easy to install in the standard spot and hold boost (no leaking) sound pretty good - If you like the high pitch pshhht then its the way to go.

other then that i have seen GFB on skylines, Turbosmart ones etc. From what i've herd the blitz bov leaks. :uhh:

Jun

[jaik]

Could also be the stock-o wastegate?  No?

Why do people refer to it as "wastegate" flutter???? Its idiotic. How can you hear the wastegate in the intake? Perhaps these internal gaters need to go for a strap in an external gated monster to hear what a wastegate does

JK

[cameron]

Lol

yeh the wastegate doesnt flutter its the pressure going back through the Compressor fins. Puts a little bit of stress on them & can cause a bit of lag during gear changes.

[dangerous_daveo]

Why do people refer to it as "wastegate" flutter???? Its idiotic. How can you hear the wastegate in the intake? Perhaps these internal gaters need to go for a strap in an external gated monster to hear what a wastegate does

JK

I know very well what sound an external gate makes

And where did I say that the wastegate flutters? I was simply making the suggestion it wasnt the BOV.

[cameron]

You were refering to the stock internal wastegate in your earlier posts. - Well thats what i though anyway.

External wastegates sound sweet when they go off underboost, Just its frigging loud when its opening (when you dont have it plumbed into dumpie) :headbang: