Compressor Surge.. Ie Flutter!! Questions, help plz

[jazza08]

Hey peeps

After buying a Stealth FX BOV and looking into it, the spring can be adjusted. Obviously so the car doesnt stall or run rough wen coming back to idle, however if its too tight this causes a flutter noise (which we all love) known as a compressor surge. They advice (GFB) to get rid of this or keep it as little as possible as it may be harmful??

Personally i loveeee the flutter noise and was wondering if alot, or abit of it would be ok? Dont want to stuff up the turbo or anything but ive always been in love with the sound....

Also it does note that flutter generally occurs at 2-3,000rpm (dependin on turbo/boost of course) and that wont harm the turbo compaired to the load put on it at 6,000+rpm, making it sound as though it is infact ok to keep the flutter.

I know dads r33 does it sometimes and its sweet as, mates 180 is abit rarer but also sounds nice (not as loud mind you). I basically want to adjust the BOV so i can get a nice flutter if changing between the desired rpm for it to occur.

Could call it flutter on command lol

Change at 3000rpm = flutter

Change at 3500rpm = bov

Any help on this would be appreciated peeps!

Thanks all

[mass_iv]

hey, just thought id like to ask are u using standard turbo? if u are then i suggest dont leave it too long, i had mine flutter like hell on my stock turbo, and after about a month, turbo go bye bye!!! i have to admit it sounded awesome...but then again mine was unusually loud, i tell ya it turns heads like u wouldnt believe.. just play around with the screw and take it around the block, keep adjusting it till u get it the way u like.

[lucky_cefiro]

strange...my cefiro is still running stock turbo with no BOV...i beat the hell out of it and it's holding up nicely....sure it's not 5 speed. but i still stall the shit out of the turbo all the time because of the surge.

guess it just depends on the day it was built....must have a wednesday turbo....

[mass_iv]

lol.. yeah i got the shits with it, was running fine, and then, started to make this squiling noise, i took it to tony rigolli and he said sorry mate turbo gone, now i have to choose between a gcg highflow/rebuild and an upgrade. try taking off the vacuum to the BOV and listen to wat it does, sounds so cool like a vl turbo hehehe, but not good for the turbo.

[lucky_cefiro]

dang, i just went to a local yard and picked up a t3 outta a vg30et for $40CAD...swap her in when i pop this one.

lol i know about the sound...this stupid cefiro didn't come from the factory with a bov. I got a 1st gen dsm to put on...becasue i'm cheap and it's good to 20psi or abouts there if i crush the top.

[jazza08]

The turbo will be stock for a short while.. but soon will be replaced by the GCG hi-flow rb25 turbo...

Hmmm still no real definate answer here peeps, can someone who knows about the whole compressor surge thing help abit more

Comments are appreciated guys Atleast wen ur turbo goes mass_iv u have an excuse to upgrade hehe

[BenA31]

yeah i also got a cefiro stock with no bov. flutter's all the time with no issues.

[HCR32]

ive got the tension on my bov set to tight, so only on higher boost it will give you the splash sound otherwise u will get a nice flutter,

ofcourse its not good for the turbo because of the back pressure but hey, just another reason to upgrade the turbo when it shits it self

[GR33DY]

i maybe wrong guys, but there has been SO much on the so called flutter sound... HAving experience, i had a series 2 R33, and had the BOV really tight... It would flutter upto 4,000rpm... I had stock turbo, pod, fmic, zorst and was boosted to 11psi.. i had this setup for abt 1.5 years and drove with that kind of flutter for abt 40,000kms.. at the time my car had 110,XXX on the dash, and i have sold it.. i still kepp in touch with the guy who bought the car, and its still been fluttering and turbo is still in awesome nic..

theoretically, YES, flutter is bad cause its forcing air back through the turbo, however, it hasn't been proven ti damage the turbo nor the life of it... Alot of ppl have said that it WONT reduce the life of it and i agree with them because of my experience with it.. I have an s15 now and have driven abt 15,000kms with flutter with no probs..

Remember, if u import ur car from Japan, who knows what condition the turbo is in.. Just a thought.. Hope it helps!

Rob

[jazza08]

Interesting... i think i might keep alittle bit of flutter action happening hehe

Thanks peeps ne more comments will be read and appreciated!

[scottman]

i heard it was only on High boost it swears Turbo like over a bar mine does it some times at low rmps about 3 and a bit it got pSSSHH i like both

[psybic]

MANY MANY cars run NO BOV. No BOV what so ever is going to be alot worse for the turbo than a bov which has a hard ass spring.

It must hurt the shaft a fair bit when it does this, but even on super soft spring, it will surge back thru under a heavy load, so if your turbo DOES go after one month, I'd say its a dodge turbo, as most people DO NOT have stupidly soft springs that leak all the time like the typical WRX boys.

[lucky_cefiro]

you are correct, i know a few guys here with 3-4000$ turbo's in there grandnational's and they run no bov's without any problem...but then again, for every success there is a horror story, so it's really up to you if you want to find out.

[Tigger]

Is it possible to adjust the stock BOV to make it flutter?

[jazza08]

I dont believe so... grab yourself a GFB Stealth FX, one of the best BOVs around, can adjust noise levels, spring tension (flutter) or change noise by adding different trumpets etc etc

Pretty awsome lil thing!

[TurkeySlapper]

just a side note i have the oh so lovely flutter noise at low rpm with a blitz bov, but im actually a little bit over it to be honest, sure it sounds cool but under gentle backing off, particularly noticeable on the fwy if you accelerate gently, build boost, then back off gently, the flutter will last for a good couple of seconds and cause very annoying shudder thru the whole car cos the AFM is getting jerky readings. Like the stick wobbles violently and any passengers who dont know the car will look at me and ask whats wrong with it...

Any one else notice this?

Steve

[foznice]

does anyone know if it's possible to adjust an after market BOV to always vent or plumback (no flutter) at all boost levels? I don't like the flutter personally, but because at higher boost levels you need to tighten the BOV so that it dosn't leak, but at the same time I don't want any flutter on the lower boost levels....

[jazza08]

Depends on ur bov and if spring adjustment is an option or easy to do!

Generally u wud have to change the bov in regards to which boost level your running for wat you want... ie loosen spring on low boost, tighten it up if ur running high boost

[psybic]

Before selling my turbo celica, I played with BOV sounds alot, as I was marketing for a young ricer who wanted a "cool" turbo car.

My car actually started off with the loud pssshhhh, then after rebuilding the turbo and removing the AFM (remember the 3SGTE AFM is a different setup to what you guys have), this turned into flutter, everytime, no matter how much boost.

I would suggest that you will always get a flutter unless the spring is super soft, as you will always be getting SOME air back chopping back thru the comp.

You don't want your spring super soft, it will leak.

Think about the way it all works, you have like 5psi in the inlet pipes, its probably going to flutter as its kinda easy to get back thru a turbo only spining that fast. You get like 10psi suddenly that comp is going a big fast so the equalisation that occurs is going to be a sudden psshhhh noise, so you are going to struggle to make the BOV not flutter at low psi unless you make the spring really soft.

For those that do what the flutter, open the bov and put some 20c coins in to compress the spring, this will make it harder and flutter more. If you want less noise, get another spring that is softer, or toy with making a spring from a coat hanger, its stoopidly soft and leaks like a bitch, but damn its loud!

[Sydneykid]

Some of my previous posts on BOV's;

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Oh no, the old "BOV's don't do anything" line .............

Why did Nissan fit them?

Why did the early turbo engines (someone used the NICS and RB30ET examples) not use them and had recommended turbo servicing at 60,000 ks'?

Why do the later Nissan engines have recommended turbo servicing at 120,000 k's?

Does anyone really think that Nissan wasted money on BOV's, fitting something that wasn't necessary? They would have saved millions of dollars over the life of R32/33/34 and S13/14/15 and Stagea and ............you get the drift.

Does any out there really believe that comparing race cars with no BOV's and road cars is realistic? Give me a break, we service turbos every 2,000 ks' of racing. Personally I don't want to be doing that on my road car.

With a boost gauge plumbed to the comprressor housing you can easily see what happens to the pressure at the compressor when you close the throttle without a BOV, double the set boost limit is not unusual. Does any one really think that that is somehow good for your turbo?

Everyone has heard the turbo flutter noise when the throttle is closed and no BOV is fitted and noise = vibration at the tubine blades. Does any one really think that that is somehow good for your turbo?

As for slowing the rpm versus reversing the flow. On the engine dyno I have seen large amounts of air flow out of the compressor inlet on throttle close. That air is coming from somwehere and it has to get past the compressor blades to get out. So I have no problem with the thought that the compressor blades stop or turn backwards. Even if they only slow rapidly, does any one really think that that is somehow good for your turbo?

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The idea of a BOV is to prevent the air from reversing direction when the throttle is closed. This has 2 effects;

1. It prevents the compressor being suddenly stopped (or run backwards) when the air rushes back the wrong way.

2. It keeps the air (in the intercooler and pipework) moving in the right direction ie; towards the engine.

So it would appear to me that #1 would be satisfied no matter where the BOV is located. But #2 is best satisfied by having the BOV as close to the throttle body as possible. That way none of the air is going the wrong way. This would mean better throttle response when the throttle is re-opened.

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So by not running a BOV or by excessivley tightening it, you are shortening the life of your turbo and you are decreasing the performance of your engine. It seems like a dumb idea to me.