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Discussion Starter · #1 · (Edited)
So I just received my GoFastBits DVX blow off valve and planned to control it from a CP-E maptap on the intake manifold. Reason is to avoid it blowing off too often as I have read about Turbosmarts here on the forums.

GFB seems to recommend using the oem solenoid.

Here is their response:
"The main difference between the stock diverter valve and the DVX is the amount that the valve opens. The factory valve is not progressive and will either be open or shut, whereas the DVX is progressive due to the stiffer spring and use of the pilot valve DV+ style design.
The DVX incorporates a spring preload adjustment screw on top of the valve to adjust the timing and speed of the piston shutting. Although the valve will still be completely controlled by the ECU in terms of WHEN it opens, the amount vented and the closing time of the piston can be adjusted. By adjusting the valve to only vent the required amount of air, throttle response will be at a maximum.

Having said that, it is possible to run this valve off the manifold pressure, but the spring in the DVX may be too stiff as it was designed to operate with almost a true vacuum (provided by the engines vacuum pump) and the manifold does not provide enough of a vacuum.

Basically, the DVX has been designed to only vent the required amount of air to prevent surge and also retain the full throttle response possible. I would recommend retaining the solenoid and adjusting the DVX to gain the best throttle response."


Those running "any" bov control from the intake manifold care to comment?
Would spring still be too stiff even on its softest adjustable setting?
 

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The oem solenoid gets it's vacuum source from the vacuum pump not manifold/engine vacuum and is controlled via ecu. There is nothing wrong with the turbosmart or others. Once you bypass the solenoid and run it off the manifold all the issues go away with early/erratic release. Thats the first thing I do to cars we tune. Get rid of the plastic lines and replace with 1/4 vacuum line and done. You'll be fine with the spring pressure. We have ran up to 12lb springs on BT setups and vacuum still opens them
 

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The problem is running to soft of a spring off the manifold. The factory source uses a much softer spring. This will result in the valve staying open when not in boost. It also creates a delay when spooling the turbo. Now instead of the valve being shut and ready for boost it has to get boost pressure to close the valve. I experimented with this and the delay was noticeable. I do not recommend it. Follow the manufactures instuctions.

Sent from another garage.
 

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The problem is running to soft of a spring off the manifold. The factory source uses a much softer spring. This will result in the valve staying open when not in boost. It also creates a delay when spooling the turbo. Now instead of the valve being shut and ready for boost it has to get boost pressure to close the valve. I experimented with this and the delay was noticeable. I do not recommend it. Follow the manufactures instuctions.

Sent from another garage.

I have the forge BOV and have it running off the manifold. While cruising on the highway in 6th with slight throttle the valve will open, this usually happens when boost pressure is between -5 to -3 psi. Does this mean I should use a stiffer spring? Right now I'm using the yellow spring.
 

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I have the forge BOV and have it running off the manifold. While cruising on the highway in 6th with slight throttle the valve will open, this usually happens when boost pressure is between -5 to -3 psi. Does this mean I should use a stiffer spring? Right now I'm using the yellow spring.
Yes. The valve should be closed at idle. Your not going to suck in unfiltered air, but you will interduce some lag.

Sent from another garage.
 

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Yes. The valve should be closed at idle. Your not going to suck in unfiltered air, but you will interduce some lag.

Sent from another garage.
Well the valve is closed during idle and while cruising with no throttle input, but once I give it a little throttle it will open until I get into boost then it will close. Guess I'll just need to try the stiffer spring and see how it performs
 

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I'm running my Tial BOV off the manifold with a 10psi spring and I couldn't be happier with how it operates. I get NO flutter what's so ever and the fluttering with the stock solenoid at WOT has completely gone away. This way has also got rid of the erratic release that I had with my turbo smart BOV. The constant blowing off drove me nuts! I say run it off the manifold. That way you get true vacuum and it's not controlled by the computer. Just my two cents.
 

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It's a noob question I know, but from what I am reading in this thread, is it better to run a blow off valve outside of the turbo. Or are the Boomba, Turbosmart, etc blow offs that install in the factory location not the best option? thanks
 

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It's a noob question I know, but from what I am reading in this thread, is it better to run a blow off valve outside of the turbo. Or are the Boomba, Turbosmart, etc blow offs that install in the factory location not the best option? thanks
If you got to an aftermarket turbo you will most likely have to relocated the valve. If your on stock its personal preference.

Sent from another garage.
 

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A single piston BOV using manifold pressure will be open at idle and in most conditions during vacuum cruise. The benefit of the solenoid is it can keep the valve closed (disallow vacuum reference to the valve) which increases spool and throttle response.

If you are running the valve on manifold pressure and it's not open at idle, the spring is too stiff. It should begin to close once you near 70-80kpa give or take.

You'll notice at idle with the valve open, air is venting from the valve, not pulling in air.
 

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A single piston BOV using manifold pressure will be open at idle and in most conditions during vacuum cruise. The benefit of the solenoid is it can keep the valve closed (disallow vacuum reference to the valve) which increases spool and throttle response.

If you are running the valve on manifold pressure and it's not open at idle, the spring is too stiff. It should begin to close once you near 70-80kpa give or take.

You'll notice at idle with the valve open, air is venting from the valve, not pulling in air.
I went off the chart according to TiAL. Using their recommended springs my valve is closed at idle and vents perfectly.

Sent from another garage.
 

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I went off the chart according to TiAL. Using their recommended springs my valve is closed at idle and vents perfectly.

Sent from another garage.
You may be able to get away with a lighter spring. Their chart is just generic based on vacuum and each car's turbo, charge piping, VE, etc. will require fine tuning to get it just right.
 

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You may be able to get away with a lighter spring. Their chart is just generic based on vacuum and each car's turbo, charge piping, VE, etc. will require fine tuning to get it just right.
I've tried a few different springs. I found the TiAL plain spring holds the valve shut and lets it vent properly. Same one listed for the amount of vacuum we pull at the manifold. I measure this with a Defi boost/vacuum gauge.

Sent from another garage.
 

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So solenoid, manifold which is better? Or can both work properly if setup right? I had a turbosmart valve for a few months and couldn't stand the light throttle constant venting. Torrie adjusted my tune, and it helped some, but it never was 100%. I read everything I could at the time about the situation, and some said to using the manifold vacuum fixed it. Others said that it was a result of the small k03 turbo building boost so soon, and was unavoidable. I gave up and put the stock valve back in. I am eventually wanting to switch to a gtx turbo and a hks bov, but don't want to run into the same problem again. Is there a clear cause/fix to this? Or is it split with some believing one thing and others swearing the opposite? Is this another oIL catch can type issue?
 

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A single piston BOV using manifold pressure will be open at idle and in most conditions during vacuum cruise. The benefit of the solenoid is it can keep the valve closed (disallow vacuum reference to the valve) which increases spool and throttle response.

If you are running the valve on manifold pressure and it's not open at idle, the spring is too stiff. It should begin to close once you near 70-80kpa give or take.

You'll notice at idle with the valve open, air is venting from the valve, not pulling in air.
Very good point. Thats exactly why I used the Forge dual piston on my BT setup.
 

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I don't know if I mentioned this here. I did have noticeable turbo lag when the valve was open at idle. What happens is the valve has to close to creating boost pressure. Well it needs equal boost pressure on both sides to close. So if your valve is open it takes longer to build the pressure to close it creating lag. MCM on their second channel has a nifty video explaining that. I'll see if I can hunt it down.

Sent from another garage.
 

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If you got to an aftermarket turbo you will most likely have to relocated the valve. If your on stock its personal preference.

Sent from another garage.
Thanks. For now im going to build for stock turbo. later on when i want more power. I will go Big turbo. So I guess I don't need an relocated blowoff valve for now
 

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Sorry for the newb question, but I figured its relevant to this thread, so I'm gonna ask away here.

I do not have an aftermarket bov/bpv, but I have a rousch intake (and depo intercooler) and im currently running the cobb OTS stage 2 tune. My car seems to "blow off" so frequently it drives me nuts. Its hard to just try to maintain speed while driving, and not sound like a ricer. Literally every time I let off the gas I hear it blowing off or fluttering. Thats also my other problem, is I get a LOT of turbo flutter when I am being very light on the throttle. I know its not necessarily bad, but it drives me crazy.

So my real question is, does changing the vaccuum source for the BPV make all of this go away? Is it even possible with the stock BPV? Do any of you guys have any suggestions on how to get rid of this? I plan on upgrading my exhaust in the spring and then getting a better tune...not sure if a better tune will take care of it or not.

Thanks guys, I appreciate any and all help.
 
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