Almost RICE..........but need advice for experiment with 930 BOV

[Craig 930 RS]

That little black canister in the center of the picture is the blow off valve.
Relieves pressure from the turbo when lifting off throttle - sends the 'backed-up' and heated air back into the engine.

So, if I disconnected the BOV outlet from the throttle body and plugged it - and took care of any issues with debris finding its way back *into* or contaminating the BOV.....anyone with 930s know if there is any harm in futzing with this in this way - for a temporary thing? Kinda ricey, but.....

BTDT stories appreciated.

[Craig 930 RS]

[RarlyL8]

You want to vent the BOV into the atmosphere?
On a CIS engine the BOV air is recirculated from in front of the turbo to behind it during off-throttle events which equalizes the pressure thus reducing turbo buffetting. This pressure equalization also insures that the air metering plate is not pulled open (shuttered) by the vacuum created during that event.
I'd leave it alone.

[WydRyd]

Nah, recirc back into the intake for quiet operation.

On my single setup, I vented to atmo and HATED the sound.

Now I'm having my two BOV's vent back into the intake for silent operatin.

[beepbeep]

That is a cheap plastic Bosch dump valve inteneded for recirculation installation.

There is nothing, I repeat nothing, to be won by trying to make it work like a open-ended BOV. Firs of all, it doesn't seal 100% when there is no boost in system so you will end up sucking dirt on low load. Second, it will dump already measured air into atmosphere making engine stumble and go rich when shifting.

Connect it back the way it wasm and don't worry about "sending heated air back into the engine". That is not the problem.

[sand_man]

Venting to atmosphere with CIS (if that's what you're asking) is a bad thing. It causes the fuel plate to stall which can cause a lean spot.

See PorschePhD's response in this thread:
http://forums.rennlist.com/rennforums/showthread.php?t=209805&highlight=Blow

[AvonGil]

Venting the atmosphere is not acceptable in a CIS car. You cannot simply dump it outside for it will cause the plate to fall as stated before.

What you can do it just buy a better valve that will hold up to temperature and open faster. I used to use the Forge bypass valve. Looks exactly the same, but was made of aluminum and used high temp seals.

These guys used to sell it. Now they sell similar ones that look a bit more fancy.

http://www.stratmosphere.com/index.htm

[AvonGil]

I had one of these but black.

Here are pics of a broken bosch valve (not good over 15 psi or so) that I took apart.

http://www.alvarogil.com/volvo/Photo_Album/CBV/Broken_Bosch/


Here is a great article comparing valves:

http://www.s4biturbo.com/art-dvtests.php

[Craig 930 RS]

Glad I asked. Was thinking of futzing with the BOV for the heck of it.
Most other cars car can take this change with no problems.

And I agree with the 'no advantage' - there is none. Cute sound, but it gets wearing.

Basically curious if it was something I could play with, aka "dump to atmosphere". Nope.

Thanks!

[WydRyd]

One thing interesting I learnt is that BOV's, like the one pictured above, are not unidirectional. You can actually use either "nipple" as the inlet.

With the side as an inlet, they blow off later and tend to seal better at higher boost levels