Don't get on the man for replacing the BOV. Mine leaked like a freakin' sieve until it got below 10psi. It's inevitable insurance to buy the BOV and the APS unit makes it bone simple. Just screw on the right hoses and she works great. No screwing around with ANYthing.

In my case (YMMV), the sound was strikingly evident and louder than stock. Perhaps that's because my stock was so bad. People near the car and in the car all noticed it immediately my 16 year old shook his head and my 12 year old smiled ear-to-ear. Me? I smiled cuz it didn't leak at boost leak test any damned more.

 

It's the stock intake that is masking the sound. Put a intake on the car or at the very least put in a drop in filter (HKS or K&N) then you'll get some more sound out of it.

 

I turned the allen screw all the way in (clockwise) on my APS bov, just enough so I could still tighten the nut on the threads. It runs a lot smotther in between shifts that way....

 

You're reducing your BOV's ability to vent by doing this. It may run smoother during shifts, but it could also be stalling your turbo during shifts, which is a bad thing.

 

I really don't think it's the BOV that makes the sound people hear when they install an intake.

The sound they hear is the rushing in of air (through) the intake. It becomes more audible when the stock configuration is changed.

I used to have a supercharged M3. It had a recirc 'bov' and the only sound was from the intake.

You have to remember - a turbo/supercharger is nothing more than a pump.

 

Stalling your turbo?

Could you elaborate on this?

Thanks...

 

the turbo takes low pressure air, from the intake, and compresses the air by spinning really fast (think about a multiple speed ceiling fan), and moves it on down the intake pipe. The faster a turbo spins, the more air it can supply to the engine. When the throttle body closes abruptly during a shift, the air has nowhere to go except through the BOV. If the BOV doesn't relieve the pressure and give the air somewhere to go, the air will actually go backwards through the turbo, slowing it down dramatically, very quickly. It's also called surge, and is very damaging to the turbo's longevity. It's a bit simplistic viewpoint, but I hope that helps.

 

Nah, it actually does enhance the sound of the BOV as well, because the BOV is venting back into the intake tract. The sound is more audible with an aftermarket intake than with the stock, enclosed airbox. This is in addition to the spoolup, jet-like sound.

 

Yes - but the stock BOV and the MR BOV are 100% recirculation. the APS is partial VTA - so in that case if you really worried about VTA you should have gone with the JDM MR BOV!

Well, Actually, The APS is an awsome unit from what I hear.

First stage recirculates till the boost crosses a certain level, then it VTA.

One word of caution - if you change or put the spring in yourself have to seat the spring not just insert it.

 

OK, with regards to not really being able to hear a BOV.

I guarantee you will hear the HKS SSQV. You can scare small children, clear the road of deer and generally make an *** out of yourself with that BOV. Its incredibly loud.

I have one sitting in box FS with a full ver2 kit

 

Okay.

I understand.

What are the symptoms of 'surging' etc...?

 

can the turbo be damaged with the stock bov on backwords?

 

chronic symptons - poor part throttle driveability, for instance uneven power delivery under constant throttle input, or abrupt loss of power under slight lift of throttle, just to come back a split second later.

acute symptoms - turbo failure.

 

I don't have first hand experience with a bov installed backwards, but I would certainly think so. When you lift throttle, the piping prior to the throttle body stays under pressure while the manifold goes under vacuum. So the BOV has a suction on one side of the BOV diaphragm trying to pull it open, and pressure on the other side trying to blow it open. Two forces combined make the BOV open. If you install it backwards, you will lose the force that is trying to blow it open and only have vacuum trying to pull it open.

 

Interesting stuff.

Now I understand.

If the BOV were 'turned' down too low (making it harder for the piston to open) the built up air wouldn't have any place to go. Thus going back towards the turbo. You have to lessen the springs tension to allow the air to recirc or vta to relieve the stress on the system.

Thanks!