BOV boost limits

[Mr Peepers]

I may have misunderstood your post, Alpha, but just to be clear:

Hooking the lower port back up to a boost source will return its operation to stock(like it was never DG modded) and it will leak at the same psi as stock would(~20?).

Leaving the bottom port open to atmosphere will hold any and all psi.

[ForceFed86]

I agree with mr.peepers. I also run a dodge garage BOV I modded. I peg out my 35psi gauge daily and have never had a problem. On a side note 2 DSM bov’s may be needed for large IC’s 3” piping etc. Still the cheapest quality BOV around IMO. I run one on my SC300 as well. They will also polish to a mirror finish.

As far a quick release goes…
 I was thinking you could set up a small inline pressure tank to store volume. Then rig up a vac solenoid inline with the lower port and your charge piping. The Vac solenoid will be normally open allowing vac/press into the lower chamber. Then use a WOT switch (or jakal’s TPS position out) to Close the solenoid at WOT. This will give you a fast release and allow you to hold 35+psi….or so I’d assume?   

[AlphaVision]

Got it now! Thanks guys. Will remove the lower hose then...

[Kapok6]

I agree with mr.peepers. I also run a dodge garage BOV I modded. I peg out my 35psi gauge daily and have never had a problem. On a side note 2 DSM bov’s may be needed for large IC’s 3” piping etc. Still the cheapest quality BOV around IMO. I run one on my SC300 as well. They will also polish to a mirror finish.

As far a quick release goes…
 I was thinking you could set up a small inline pressure tank to store volume. Then rig up a vac solenoid inline with the lower port and your charge piping. The Vac solenoid will be normally open allowing vac/press into the lower chamber. Then use a WOT switch (or jakal’s TPS position out) to Close the solenoid at WOT. This will give you a fast release and allow you to hold 35+psi….or so I’d assume?

I understand part of what you said and it makes total sense.  I understand the concept of a solenoid incorporated, i.e at WOT no pressure to the bottom port, at anything under 90% WOT or whatever, you have pressure to the bottom port for quick release.  What I don't understand is the whole "pressure tank."  Can you elaborate?  Sorry, my reading comprehension isn't what it used to be when I was a kid and I kind of need to see picture or in person to understand the operation. 

[ForceFed86]

I understand part of what you said and it makes total sense.  I understand the concept of a solenoid incorporated, i.e at WOT no pressure to the bottom port, at anything under 90% WOT or whatever, you have pressure to the bottom port for quick release.  What I don't understand is the whole "pressure tank."  Can you elaborate?  Sorry, my reading comprehension isn't what it used to be when I was a kid and I kind of need to see picture or in person to understand the operation.

The pressure tank theory is to help assist with quick release. As Mr. Peepers said. (man I feel odd writing Mr. Peepers all the time!) I’ll explain what I was thinking and also how it may not be necessary now that I thought about it a bit more.

I've pondered over setting up a solenoid to send pressure to the bottom port once you let off the throttle, but I think the problem is how much time it would take to fill the lower chamber(the key thing is response in the first place).  The secret is having the lower chamber already pressurized, but not quite pressurized enough to make it leak when at full boost.  Just get the extra oomph to make it open a little quicker.

So lets assume you had a pressure tank of some sort with similar (or slightly larger) displacement as the BOV diaphragm (this wouldn’t be very large) mounted directly behind the solenoid. Then make sure you use as little vac tubing as possible between the solenoid and the lower BOV port. This way as you are boosting the “pressure tank” is filled but cannot bypass the solenoid at WOT. As you lift the solenoid opens and allows a greater supply of volume (from inside the pressure tank) to enter the chamber at a faster rate. In theory this would open the valve more quickly than a straight run of 1/8th vac tubing routed to your charge piping.

That being said...
 Once the throttle closes your charge piping is pretty much a huge “pressure tank” anyway. So if you had an extremely short run from your charge piping to the solenoid and another short run from your solenoid to the lower port it may accomplish the same thing. It might be easier and slightly faster to run a small pressure tank mounted right to the solenoid. You could also mount the solenoid directly to the BOV port.   
 

[Kapok6]

I think I understand.  Would help if I had a visual diagram or something but I believe I understand the concept of how it would work.  I just don't understand the pressurized cansister part, how big it would be, exactly where it would be placed, or even why it's necessary.  I would think you could just have a tap in the IC going to a vaccum line, the vaccum line going to the colenoid, then another vaccum line going from the solenoid to the lower port of the bov, then set your parameters in jacka for the FPR and be good to go.  I don't understand why you need to incoporate a canister.  I apologize if I am coming across a dense.

[ForceFed86]

And you may be right...

We are talking milliseconds here. So think of the time it takes to fill x amount space (bov chamber) with y amount of pressure, traveling through z length/diameter of tubing .
 Obviously it will take less time to fill the BOV diaphragm from a large volume reservoir a ¼ inch away, than it would take to fill the diaphragm from 10” of ¼”(low volume)  tubing tapped into your charge piping.

 Like I was saying above if you tapped the charge piping right next to the BOV with a minimal amount of tubing I think the results would be similar. That may not be easy for most to do. Doing it the way I suggested you can tap your IC piping anywhere you want and run a long length of vac tubing if necessary. 


Heres my original BOV...



Little elbow grease and the DG mod. 

[Kapok6]

Yeah, I have polished a few.  They polish up really nicely.  How exactly would this canister maintain pressure and how big would this canister need to be?

[ForceFed86]

Yeah, I have polished a few.  They polish up really nicely.  How exactly would this canister maintain pressure and how big would this canister need to be?

Um... like I said above, small. Basically slightly larger than the area in the bov diaphragm (technically half the area of the diaphragm.)A Golf ball comes to mind. It is plumbed into your charge piping. It will have pressure As long as your charge piping does. To step it up a notch you could use a tiny pin hole on the supply side of the canister (.050 or so), and a full size on the side pointing to the solenoid. This will help keep the pressure flowing to the BOV side vs back into the charge piping.

[Mr Peepers]

A quick and dirty method that I was using before was to tee the bottom BOV port into the line going to the wastegate when using a MBC.  When the MBC is all the way out, it will let the wastegate see all the pressure and boost will be the lowest.  The BOV bottom port will also see all the pressure and release will be the quickest(like factory).  As you turn the MBC up, it will slowly block off some psi from being seen from the wastegate, "tricking" it to raise the boost.  At the same rate, the bottom port to the BOV will also see less pressure and be less likely to leak under boost.  More boost via MBC, less quick release function but more psi holding capability.  Works out quite nicely and is how I had my 14b and 16g set up.  Stopped the "bark" when letting off at 20+ psi.



The idea I posted before was expanding on this old setup, but making it more tuneable depending on WG spring pressure, MBC type, and desired psi.

[big_d]

Bringing this one back.  Matt and I discussed DG modded bov's a bit on tuners about a month ago.  I have been contemplating where I want to go as far as hose routing is concerned.  I have a 3 port fuel pressure solenoid that I would like to try to activate using Jackal... By using a TPS (possibly) threshold, I should be able to expose the lower port of the bov to atmosphere.  When I lift from the throttle, the solenoid will allow boost pressure to fill the bottom port.  As previously stated in this thread, what kind of times are we looking at for this to occur?

The old Dejon stop leak kits that were sold worked exactly this way correct? (the MAC valve they used was at a set boost pressure of 15psi)  If I mount the solenoid as close to the bov as possible and keep my threshold pretty high (95%+ throttle), how do you think "quick release" response will be?