I was wondering if anyone gets turbo flutter from the Dejon Upgraded BOV spring.

 

What do you mean by turbo flutter? Where the boost goes up and down a little bit?

 

i am really not sure. I was talking to someone that has it installed and he said that he has turbo flutter at low boost

 

I have none. It releases just fine. It is 13 lbs/in. Stock spring is 9 lbs/in. The cars sees 20lbs of vac when you let off so it opens just fine.

 

has your computer picked this up or or it cant

 

20lbs of vacuum? I'm pretty sure it's only 20inHg, which is ~70kPa, which is only ~10psi.

 

Oh, yeah, i have had no problems at all. I have heard of only one CEL from the spring upgrade, otherwise, no problems.

 

by turbo flutter I think he is refering to turbo "surge", which I guess sounds like "fluttering" lol.. isnt this bad and undesirable?

 

From what I understand, if you are tuned, you will have a bit of surge, but if you are stock, it might be something to have checked out.

 

i do, i think it sounds sweet. its not bad is it? it doesnt happen all the time tho

 

YES turbo "flutter" or surging is bad!

I get it some when I flutter the gas! But under WOT no it holds 22.25 psi and goes to 20 in/hg when I let off the throttle!

 

Yep i get that sound if I blip the throttle. It's normal and not much you can do about it.

 

You can do alot about it.... not blip the throttle!

 

yep exactly

 

please educate your self about turbocharging before you modify your car

 

IMO, this thread speaks for itself as to why you would NOT want to do this mod.

 

Why not then? I have it, I have had no problems. I would like to know your reasoning behind that.

 

Why? How about...

That's not enough for you? The spring messes with the transition range in and out of boost like I suspected in the other BOV spring thread. It might be in the LNF section if it's not in here. From what I understand, the car has approximately 9~10psi of vacuum at idle (funny how the stock spring is 9psi, isn't it?). At this point, the valve is fully open. As you apply throttle, the vacuum psi reduces as the intake manifold approaches atmospheric pressure and/or boost and the valve begins to close (because of the spring). Once in boost, the hose that connects to the outside of the BOV is keeping the valve closed (like blowing on a straw) on top of the spring pressure. Changing the spring might help keep it closed as boost pressures increase....but the side effects are damaging in the long run if you are hearing flutter/surge from the turbo.

 

We're talking about different units here. Spring constant is in lbs/in. Pressure is lbs/in˛ (or in. Hg, but I thought it was psi on the boost gage). So you would need to know how much area comes into play on the bov and then you could calculate how much the spring will compress. I'm not exactly sure 100% how a bov works, but I don't imagine a stiffer spring would do much good. Stiffer would make it close faster? Or does it make it open faster?

 

Engine vacuum overcomes spring pressure to open the valve progressively. So, as vacuum increases, the valve opens more and more because the line connecting to the BOV is pulling against the spring pressure. When the engine is at atmospheric pressure, the spring is closing the valve 100% with no other forces being applied. When in boost, the line connecting to the BOV and the spring pressure both push on the valve - but the other side of the valve has just as much pressure pushing against it. As long as the surface area on both sides of the valve are equal, there should be no issue with the valve staying closed....as long as the spring is healthy. The true solution to leaking boost IMO is to replace a weak spring or slightly increase the surface area on the spring side so that there is a touch more psi keeping the valve closed.

Increasing spring pressure causes the valve to stay closed in the driving scenarios where engine vacuum is approaching 0psi, but hasn't quite gotten there yet. That's how you get the flutter. The air that would normally have some place to go doesn't now.

 

Makes sense. So it is sounding like increasing spring pressure may not be desirable afterall...

 

So, when you start pushing more boost, you're just gonna let it leak?

Also, I said, that when people are tuned, the boost spikes. This is regardless of spring upgrade or not.

Otherwise, I see your point. But, going from my experience with the spring, I pull 20mm of vacuum at idle, have never had the boost spike, and have had no CELs. Just saying, that for every half bad experience, there are 3 good, at a minimum. Also, the first guy stated his friend thought he was having some... let's not play the telephone game now.

 

why do people think that they are losing boost with a factory recirc valve, there good for like 30psi or more.... lol If you have a boost leak, youll never far past 1 atmosphere.


all those bearings and twin scroll fins are really really delicate when glowing red hot (sporty driving), if your surging, your asking for turbo damage

surging is different than boost spike spike is occuring at WOT, this instance of surge is partial throttle lift.