BOV 101

[Strife26]

Hey all,
I replaced my HKS SSQV bov because I hated it. It sounded like it was causing flutter if I wasn't full boost, and even then sometimes it would. Sounds cool and all, but I think it was fluttering which I understand is bad for the turbo.

I replaced it with a Synapse R35V Trident, which I thought was my only option. Later I learned I could have just bought the adapter for the HKS setup, but oh well. I do like the Synapse.

The issue/question(s):

This BOV/DV is always open at idle and low revs. It feels right, and the car drives fine, possibly better since there appears to be little flutter if any. In discussing with my tuner he keeps telling me it should be closed at idle, and I don't disagree, but it doesn't seem like this valve closes, but instead is always open until I push the pedal. When I have some throttle going it will close, when I let off it opens releasing the air. To me, everything seems fine, butt he tuner is adamant about it being closed at idle and it definitely makes sense to me considering the afr, etc., but it just doesn't appear to close at idle. I have put a stiffer spring in and hunkered down on the preload and it hasn't changed a thing except I get a tiny bit of flutter sometimes.

Can anyone chime in to explain if I am just plain wrong and it should be closed, or is it possible that it's open at idle/low load? It doesn't seem to be sucking air in or out at idle, but I haven't thoroughly confirmed that other than putting my hand around it. I need to use a string or something to see if it moves in front of it.

Also, I don't understand the preload now that I have tried adjusting it as it's literally made no difference. Both springs do a good job, and the preload hasn't really changed much of anything so far.

Any help is greatly appreciated.

[Kiske]

For the most part closed or slightly cracked at idle with most setups. You want a bit of air to escape so that when the turbo is still spinning and the throttle blade is closed there isn't positive pressure. Some run it open at idle for faster spooling. Soon as you touch the throttle it should close until release.

If you are running a speed density tune or the BOV is behind the maf then yes, it MUST be closed.

Use your boost gauge to determine the amount of vacuum at idle. Use that to pick the correct spring. Then use preload to fine tune it. The point of having the proper spring in it is to make sure the spring pressure isn't more than what your motor can pull open.

Preload is mainly going to be seen in the car. Free rev it and quickly let off. Watch the RPMS. When you let off do they ever dip down blow idle or does the car stall? If so then adjust it (tighten it.)