BOV noise

[XrSiSt]

The HKS makes that high pitched noise. U can change

the noise by changing a part inside. UAS have them for

$40 each the last time i looked. They look like this.

[nissanpower]

why dont you just sell it to me and block off the hole mac30! hehe :lol:

[JimX]

Here's that site I couldn't find the other day with sound samples of various bov's. The sound quality isn't too great but you get the general idea. Personally I think the GReddy Type R sounds best, but I don't know if that's just because my car came with one and I'm used to it, or the previous owner thought it also sounded cool and I was therefore lucky to get it

http://www.alltrac.net/tuning/blowoffvalve.html

[mac30]

Thanks for the comments. Made up my mind again after Jimx sound files ..... HKS wins!!!

[Mr Squiggle]

mac 30,

HKS, good move...... I told you didn't I

(RATTLE SNAKE)

[SLY33]

Hey that supra wastgate link- the fluttering in between gear changes:- does anyone else think that sound is purely the chopping sound from the turbo due to reversion?!

Many ppl think that is a blow off sound, but if you think about how most of them work, it dosnt make sense if they made that sound- the valve would have to be bouncing open and closed!

In between gear changes, the pressure in the inlet tubes suddenly increase due to the throttle body closing, which usually pushes the blow off valve OPEN. As soon as its spring pressure overcomes the inlet pressure, the valve closes right? and once its closed its not gonna open again anless you boost it and back off again.

Please correct me if im wrong, but i think i may have it figured! Fluttering= reversion -not blow off sound??

cheers

[SlowGTS-t]

my factory valve does that...

er.. I've got a FMIC and some sort of hybrid made from an RB25 turbo...

[ex-static]

I beleive it has something to do with the piping.. heh.. as ive herad this result usually after an intercooler install, its not actually the BOV.

Your dont need an aftermarket bov on a skyline anyway.

[SLY33]

thats interesting about the piping theory, as mine only made the sound after the FMIC went on.

I reckon i have the answer though :-

How about the fact that with all the new piping and a big cooler core, you have more than doubled the volume of air in the inlet tract, so this extra air, if not let out by the BOV, will have to work its way back out through the turbo (flutter) and out the air filter, just as classic reversion!?

Thats why most skylines flutter at low boost, as the pressure was not high enough to trigger the blow off, and hence, puh puh puh puh puh puh(flutter).... This is the sound that VL turbos WITHOUT BOVs make really well!

Exstatic,

Are you saying that the factory BOV's are adequate? or that you dont need a BOV at all?

[riggaP]

This is my undersatnding (and experince) of it:

If the BOV is too tight (or simply not enough pressure to open it), the air will travel back through the turbo, get chopped and make the flutter.

If there is enough pressure to open the BOV (or the BOV is really loose), you get the psshht sound.

SLY33 I think you're on the money when you say...

  Quote

In between gear changes, the pressure in the inlet tubes suddenly increase due to the throttle body closing, which usually pushes the blow off valve OPEN. As soon as its spring pressure overcomes the inlet pressure, the valve closes right? and once its closed its not gonna open again anless you boost it and back off again.

[nissanpower]

my friend has the flutter sound on his s14

he just disconnected the vacuum hose on the standard bov (therefor bov is not working) and i guess the air gets pushed backwards thru the turbo making the flutter sound. the sound really only works if you rev alot.

i also tried it on my 33 and it made a similar sound.. not exactly the same. but after boosting it and i come to a stop the car stalls. getting mixed air/fuel i think

wonder why skylines will stall and 200s dont

[Doctor]

Yeah the car stalls due to reversion. Air passing back out through the turbo cools down the element on the AFM causing the engine to run ruch.

I beleive there are two causes for that noise both result in reversion.

1. BOV to tight, causing air to get bounced back from the throttle body then through the turbo and "getting chopped" by the compressor blades.

2. FMIC installed, volume of air is increased substantially and air cannot escape out of the BOV fast enough causing it to reverse back into the turbo then once again air gets the chop.

Doc

[Grim]

And that fluttering sound made by reversion is BAD for your turbo. It causes unnecessary back pressure on the turbine blades so if yours is making that sound your BOV is too tight. Loosen it up and it will do it's job better allowing the turbo to remain spooled during gear shifts.

[nissanpower]

any idea why my skyline stalls due to reversion and my friends 200sx doesnt?

[Grim]

if you're running a BOV that vents to atmosphere then the engine would stall due to running rich.

[nissanpower]

nah read my earlier post

my friend disconnected his vacuum hose that runs to the standard bov. therefor making it not work creating reversion and fluttering.

i tried it on mine too, but after giving it a hit and coming to a stop it stalls.

both of us do not have any aftermarket bov.

[_turtle_]

i reckon the fluttering sound sounds nice

i only noticed it happening to my friends cars after they put on a pod filter..??

[NIZ30]

The reversion sound comes back out through the air filter. A standard air filter box is more quiet than a pod filter. So it apears it is not happening, when it is, you just can't hear it happening.

[thrash_demon]

hahaha my passage makes a very reversion similar sound to that supra, i dont even have a bov and am running standard boost!! i still get looks from pedestrians but have purchased a turboxs type h to get a nice crisp sound...

[cowboyb]

my R33 has a K&N pod filter, and it makes a fluttering noise when I take my foot off the pedal. Quite a nice sound really.

I've also got a Greddy Type S BOV and it makes this "lazer" high pitch noise when the car is on boost (when changing gear). Both goes really well together...

CBB

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