How much audible flutter/surge is normal.
 

Ok guys, I finally got everything sorted and running the other day and took her out to start tuning/playing. Its running stupidly rich in boost so it almost chokes itself out until about 5k...but thats a different problem >.<.

But when driving, right around the vac/boost threshold (or in vac when I let off the throttle lightly, not a full lift) I get a very audible compressor surge sound and sometimes under light throttle/boost I get a turkey call sound under slightly lift.

Here is the weird thing, even when I am boosting 7-10lbs and let off the throttle and the BOV pops, I can still hear like a turkey call coming from the turbo/intake-ish area. It is loud.

My roommate was driving behind me and said when I blow off, there is a noticeable amount of smoke/shit exiting the exhaust at the same time as the noise...I figure it could just be running rich as shit and dumping fuel off throttle, but he said it was white-ish. :O




WTF? is this normal?


Here is a picture of the engine bay...I have a big filter on a stick coming out of the turbo now.
Attachment 208846

when I was riding with Slos13 in his car and he was driving he didn't have any flutter, however because my driving style was different, it fluttered EVERY time I lifted off the gas. Not sure about the smoke, but you may need to add a helper spring to your BOV if it is too stiff

dont you mean put in a weaker spring?

you know what I mean :hustler:

you could put in a weaker spring or I've heard of guys clipping some of the stock spring off

Yea, sounds like the BOV needs adjustment.

Vash-

Yeah, weaker spring would be the best option. I have the same problem, and haven't tried to fix it yet. I probably should though.

just giving you a hard time:)

and yes: weaker or cut spring will help fix the flutter if its indeed from bov being too tight. just make sure you dont over do it, cause then it will suck at idle and cruise

What does compressor surge sound like? Is it just something you will get if without a BOV or if your BOV setting is too tight?

I'm also curious what the white smoke at liftoff might be and if it's due to BOV setting/compressor surge.

stock PCV? :dunno:

Turkey like.

Vash-

the crazy thing is some people think its cool and drive that way

^^^ Agreed, crazy. Even though I did not 'need' it with low boost, I put a BOV on my old 7 psi BEGI-S setup just to get rid of the annoying gobble-gobble sound.

Back to the OP. I Agree with the posts above; try lowering the preload if you have an adjuster, or use a lighter spring.

That was the other video I found under "compressor surge" on youtube. You mean you don't think turkey noise is cool? :bowrofl:

I had the HKS SSQV, but now I'm looking for something different, I just cant decide. I like loud BOVs. Its not like I'm always driving around making it pop off like a loud bitch. But I like having that option. :)

Vash-

Mine sounds like the vid. 18 PSI posted, but not that loud (from in the car anyway). Guess I need to get a softer spring for my BOV soon.

I mean how horrible is it for the turbo? My bov opens up at anything over 5psi, only at light throttle do I get any comp surge.

I'd like to know this too. I've heard it's bad, terrible, and destroys the compressor. And then I've heard it's harmless below 7ish PSI.

If I drive like a normal person, it doesn't do this. If I drive like I always do, which is sorta aggressive, it flutters/gobles/w/e when I shift till my BOV wakes up and opens. And does it whenever I boost too.

Thanks! I knew about the turkey gobble, but I wasn't sure if that was actual compressor surge or if there was another sound that the actuall compressor doing something to show you it's surging.

I have my Forge on the lowest spring supplied with my BOV, but I still get some turkey gobble. I also get another sound that's barely audible and a bit higher frequency when I let off the accelerator at 1-2 psi of boost. It sounds more like a muffled click.

I ordered the lowest setting spring for the Forge and I'm hoping that will take care of it.

you should look into the turbo smart valves like the 50/50. it has two ports that are staged or timed(which ever you wanna call it). it also has horns that are removeable and replaceable.
The horns make 'em super loud. I run the first stage port with a flange that is for recirculating(quietish at low boost) and the second stage with a horn so I can be ignorantly loud if I wanna. you can also adjust the sring preload with out any tools. they have basicaly a hand grip and you just turn it to adjust. and there is a large range of adjustment too.

for you guys that are still running an afm you can use one of these to recirculate and have a nice vta at the same time. it doesn't totaly keep your afm from going nuts, but it makes it a million times better.


TURBOSMART: BLOW-OFF and BYPASS VALVES (universal fit)

check out the one at the bottom of the page. I have this one, but in the all black sleeper series

Thanks guys. It sounds exactly like it does in that first video, little more pronounced sometimes than others. Weird thing is it only really does this in vacuum or low boost....when there shouldn't be much pressure.


I've got a TurboXS RFL...I need to see if they make a lighter spring/clean mine/do whatever if its going to be a problem. Like Pat I've heard mixed opinions on how bad it might be.

I've got the same problem. Mine is a cheap knock-off that came with two springs. With either one spring, it's wide open at idle, but with both I get a little bit of surge at low boost. Maybe I should cut one of the springs.

Corky (over at m.net) said he's never seen a damaged compressor from not having a BOV. Also, he doesn't believe it's possible for the compressor to get damaged w/ lack of a BOV.

I have. My friend still has the big ass fp green turbo we took off his sti after it shit itself. vacuum line going to his bov melted, and for a while he didnt have a bov running 22psi on the sti. hes an idiot and didnt realise till it was too late. I can try to post up pictures of how raped his turbo is. shaft is bent so bad the compressor wheel grinded against the compressor housing shafing off like 2mm off the wheel. its horrid

Corky:
In my time I've never seen a surge induced turbo failure. At present I do not believe it possible to hurt a turbo by not having an anti-surge valve.

Porsche did not use a-s valves on their Le Mans winning turbo cars. One Le Mans race is probably equivalent to about 3,500,000 street miles.

A slight improvement in boost response can be attributed to the a-s valve. So can noise suppression. That's about as far as it goes... i my view.


I have yet to see a turbo suffer from no valve. I do not believe it possible to fail a turbo because of surge.

that interesting. I have a forge bov waiting to go in on my car, included are 4 springs. so the weak ass yellow spring that barely holds the thing shut is still causing your car to surge? thats not good

Not taking away anything from you or your friend. I just quoted what I read from Corky at m.net.

I wont argue with "THE MAN" but I sure do disagree....
I hear ya man, I would never argue with Corky either. I would love to hear an explanation of how his turbo failed then....weird

I get compressor surge as well. Although, it is at low boost levels. My old HKS unit failed completely and was only venting under high boost conditions. So, I replaced it with a new HKS unit. Now, it vents 100% under all conditions, but there is still compressor surge. I am not going to worry about it until if/when something happens to the turbo. FWIW, I have had that mild surge since I installed the set up a year ago, and it is my DD. I haven't had any problems with the turbo at all.

It doesn't surge nearly as bad as either car in the videos. Most people would probably let it go. According to the Forge site though, the yellow spring's lowest boost threshold is 15 psi. The kit isn't expensive at all so I figured, at 12 psi, I might as well drop in the green spring just to be safe.

Like m/n said, I get absolutely no surge. I can induce it to a tiny bit if I try hard enough. I'm running a 14b with a recirculated knockoff Type S.

I bet recirculating helps a bit.

I've seen a turbo or three destroyed by surge. I half agree with corky though. the ones I've seen were marginal at best. meaning that they were within spec, but had a little more longitudinal slop than I prefer. in short they all made contact with the compressor housing and started to eat up fins from there.
in my original setup I was using a greddy type s, but I had to put quite a bit of preload on it to keep it from leaking at Idle. it wouldn't gobble, but it would give me one high pitched surge noise upon blowing. as a result my 16g has more for and aft play than it realy should, but since switching to the turbosmart valve it hasn't gotten any worse in three years.

See, mine is almost all in vac while its spooling but not actually in boost yet. or at MAYBE 1-2 lbs max. I can sometimes hear a different sound when it DOES blow off....idk, this turbo stuff is strange. Not enough time in the car yet, to much time in my beater BMW.

Hmm, strange thing:

I Got the Forge Spring Kit. I checked my current spring (yellow) to see how much the BOV was leaking at idle. No leakage whatsoever.

I installed the green spring and the BOV leaked like a sieve. The piston shut with a loud click when I turned off the engine. I installed 4 shims and it still leaked like a sieve.

I installed the yellow spring that came with the new kit and it leaks too. Not as much as the green spring with the shims but definite leakage with an audible click from the piston as it shuts when I turn off the engine.

I shouldn't have too much trouble figuring out the correct spring setting, but it's interesting that there would be that much difference between springs/sets.

Make sure the spring side you put against the piston is a ground flat side. If it is not it can make the piston slightly crooked in the bore and it may not seal properly.

I dont know why you guys care so much if it leaks at idle, I have tried everything on my TurboXS its the only way to prevent the slight flutter at low boost.

I'm not concerned about leakage at idle. A lot of leakage, sure, but leakage in general? No.

It's just interesting that a yellow spring from one set would cause fluttering because it shuts too tight, while the yellow spring from another set would allow a whole lot of leakage. I'll check the seating fo sho.

18psi seemed interested, so I'm just dropping in a little fyi.