This is kinda related to Fredo's (I think that's who posted it) topic a while back concerning blow-off valve adjustment. Anyways, I'm wondering if what I'm hearing at lower boost levels is compressor surge or actually blow-off valve opening and releasing pressure. If you don't know what your BOV *should* sound like, how would you tell the difference? At max boost levels (6-7psi) I hear more of a loud single shot of air with a couple "flutters" at the end when letting off the throttle. But if I let off the gas at like 1-3psi I hear more of a softer fluttering air sound only. Is that the compressor surge? The fluttering at lower boost is more audible now because I have switched from my ghetto intake tubing and filter to ghetto screen mesh covering the turbo compressor intake. I don't want to loosen my BOV too much more because I'm afraid it will start leaking boost at high rpms and high boost like it did before when I had it really loose. But on the other hand, I don't want to be damaging my turbo with compressor surge. Can anyone lend some insight? Thx.

Justin


[Modified by justinCO, 2:00 PM 11/26/2002]

 

what bov do you have?

 

Same question here.........I have a Greddy type-S, I think........hard to tell if it's surge or BOV sometimes...

Thanks,
Nick

 

same here... apexi twin chamber...

 

I have the Apexi twin chamber BOV.

Justin

 

Well, I think that flutter sound I'm hearing at low boost lvls is compressor surge. I've loosened my BOV screw a turn and it has helped. I'm not loosing boost at the top end either but I am going to do a few more tests. My goal is to have the BOV as loose as possible without leaking *any* boost. I hate that I am so scientific and **** about everything, lol, wish I would just leave things alone sometimes

Justin

 

Hey, i dont know how I missed this post. Yeah Im still having surcharge, I don't know why and my nut is almost at the end. I have to play with it somemore but I think it has to do with the spring in the BOV. I gave its on VAC source and still sounding odd. Hopefully I can figure this out to help you. Worse comes to worse I'll get a new BOV or send this one back, maybe its defective.

 

Fredo, have you tried the way I mentioned before on your old thread? By loosening the BOV screw way out so when you drive it you *know* you're leaking boost. Then gradually tightening it in until it doesn't leak boost anymore? To me that seems to be the best way to adjust the BOV. Adjusting at idle didn't do dick for me on my car...Gonna try some more tests this weekend.

Justin

 

you're turbo'ing a car that was never intended to see boost. you're taking the right approach.

 

Try tighten the nuts and see if you still have compression surge. My understanding is when you loosen the nuts its just gonna give you even more compression surge.

 

I'll try that tonight and see what happens

 

what is it tee'ed to? if its a shared source, try giving the BOV its own vacuum source. ive tried 3 different spots on the loosest setting. first i had it on the fpr source like this manifold>boost gauge>bov>fpr. i got surging. so i did this manifold>bov>boost gauge>fpr. i got alot less surging. the last and best configuration was tee'ing it to the evac. i got to shorten the hose length to the bov considerably by doing this. i no longer have any surging now, its hard not to blow off anymore too. if anyone needs pics to this source lemme know.


[Modified by 01geeser, 11:48 PM 11/27/2002]

 

My BOV is T'd off the FPR vacuum. I have mani -> boost gauge -> bov -> fpr. I have my wastegate T'd off the brake booster line by itself. Where is the evac vacuum? Maybe I'll try to T off that and see if there's any different. Also, when your BOV screw is loosened all the way out, don't you leak boost at all?

Justin


[Modified by justinCO, 7:00 PM 11/27/2002]

 

i dont have any noticable leaking. if you want the pic then PM me.

 

anyone have good luck with a particular vac. source on the d16z? I just added a Turbo XS type S (yeah, I see a lot of posts about it being junk AFTER I get it welded on ) anyways, car still makes a fluttering noise, just like the compressor surge before adding the BOV (its a greddy kit)... this BOV is tuned with washers ( ), and I have added none... I did move the vacuum source ( mani>BOV>gauge>FPR) and it seems to be working a little better... just like topic of this post, flutters @ low boost (3-5), only time I get a clean swoosh sound is if I'm really on it, and shift @ redline... anyone have a better idea for vac. source?

oh, can I get pics of your source too? (01geezer)

 

could you post pics (01geeser) of where your vacuum source is for your BOV?

 

bump

 

I have been loosening my BOV adjustment bolt quite a bit lately for more testing and it hasn't leaked under boost yet. I don't have as much surge now, I think, hehe. Definitely get more "blow-off" type sound at lower boost levels. I'm gonna locate the evac vacuum as suggested earlier and try putting the BOV vacuum on it's own source (the evac) and see how things work. I will update when I get time to test.

Justin


[Modified by justinCO, 11:04 PM 12/1/2002]

 

actually its the evap source not evac. but yeah that source is on the manifold on gsr's im not very oure about others. to those that asked for pics, they've been sent.

 

At that low amount of boost does surge matter?

 

I get the flutter sound down low also. I'm gonna try to loosen it some more. so far i got the screw half way out of the TypeS

 

Well I hooked up the BOV vacuum to the evap vacuum today and the BOV works much better now. I have not had a whole lot of time to test it out but there is definitely an improvement. I am no longer hearing the fluttering of compressor surge at low boost levels (so far). I can even get the blow off valve to open and release pressure when just revving the motor at a stand still. It would not do that before. You can see where I tee'd in the BOV vacuum, it's almost dead center in the image. The black hose tee'd into the red evap vacuum line.



Justin


[Modified by justinCO, 10:30 PM 12/2/2002]

 

Would changing the vacuum source for the bov to the brake be better

 

Probably get the same effect, as long as nothing else it T'd off the brake booster. I have my wastegate by itself on the brake booster vacuum on my car.

Justin

 

I have a B16A2, can you name all the places I can use for a vacuum source? I have so many things teeing off each other.