Jump to content
SAU Community

Recommended Posts

  • Replies 49
  • Created
  • Last Reply

Top Posters In This Topic

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 :P

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

Link to comment
https://www.sau.com.au/forums/topic/5381-bov-noise/page/2/#findComment-82852
Share on other sites

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

Link to comment
https://www.sau.com.au/forums/topic/5381-bov-noise/page/2/#findComment-83299
Share on other sites

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?

Link to comment
https://www.sau.com.au/forums/topic/5381-bov-noise/page/2/#findComment-83576
Share on other sites

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...

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.
Link to comment
https://www.sau.com.au/forums/topic/5381-bov-noise/page/2/#findComment-83669
Share on other sites

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

Link to comment
https://www.sau.com.au/forums/topic/5381-bov-noise/page/2/#findComment-88121
Share on other sites

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

Link to comment
https://www.sau.com.au/forums/topic/5381-bov-noise/page/2/#findComment-88290
Share on other sites

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.

Link to comment
https://www.sau.com.au/forums/topic/5381-bov-noise/page/2/#findComment-88340
Share on other sites

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

------------------

Link to comment
https://www.sau.com.au/forums/topic/5381-bov-noise/page/2/#findComment-90597
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Probably too late to reply to this, but worth a try. It's not calliper flex, the calliper as a whole is moving so it has to be calliper mounting bracket flex.  Calliper mounting brackets are designed to stop the calliper rotating, they don't need to be designed heavy duty to stop the calliper moving in and out.  Whatever it is is not the major cause of poor pedal feel, the outer pistons are moving towards the disc rotor the same amount as the inner pistons are moving away from the disc rotor.  Hence no change in fluid usage, what extra fluid is needed to move the outer pistons is recovered from the inner pistons. For a calliper to move as a whole by far the most common reason is the rotor is not perfectly centred in the calliper.  The first thing I check is that hub face is perfectly clean, bare metal, where the rotor hats contacts it.  Then I check the that rotor is firmly held in place by at least 3 wheel nuts (or equivalent). If all of the above are confirmed to be in perfect alignment then I would check the piston sizes and ensure that the 3 inner pistons and 3 outer pistons have matching diameters (eg; 28/32/36mm).  I have seen a no name 4 spot calliper that had 1 of the 4 pistons a different diameter. Maybe I missed it, are both the callipers exhibiting the same problem? I would remove the transfer pipe and inspect it to make sure that there are no restrictions. Maybe you already have but if not I would return them with the video and have them confirm all of the above.   Hope that helps Cheers Gary    
    • If you have the original log book and it didn't have a chassis number quoted, then no money required.  I have "rechassied" a number of race cars, no problem as long as you have the original log book.   Cheers Gary
    • Well the good news is that it won't run any worse with an atmo bov than it does with no bov, I've owned a few Nissans over the years (r32, s15 and now r33), the stalling issue caused by a bov or no bov while still having an afm is easy enough to live with, most people get used to driving them and just feathering the throttle when you come to a stop to avoid it stalling. Changing to a proper ecu with a map sensor is ideal but in the short term I'd just slap in the bov if you really want the whoosh sound. I looked into the pass through type maf like the R35 one above but decided against it as the amount of oil and crap flowing through the hot side would mean you'd have to clean it often to keep it working.
    • Build an 800hp motor. Make it as bullet proof as you want, you WILL still break things. Like, the rest of the car. Heck, even as a dead stock car, things will still break, but the more power, the more everything else will let go easier. From gearbox gear sets, to extra stress on the chassis/mounts, more stress on diff, axles, tailshaft, even the suspension mounts. Check out the motorsport build that last year went to a Bosch motor sport ABS setup, and now can brake so damn hard it's twisting mounts for suspension/subframe etc. Now if the brakes can do it, imagine what happens with super grippy tyres and 800hp in a low gear...   Shit, I'm presently out fixing the girlfriends daily driver that rarely sees past 3,000rpm and is used to cart the dogs around in. Everything WILL break. If you don't want it to break, don't drive it. And then laugh, as it will still break without even being driven!
×
×
  • Create New...