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Old 01-04-2013, 05:00 PM   #76
nate_fisher
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Ok i put the yellow back in and it made no difference in how much boost i hit and responce still feels the same so i will keep it in there. It is stupid that they put in that you need to go stiffer for more boost since the stiffer the spring the worse it reacts. Thanks for the tips.
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Last edited by nate_fisher; 01-04-2013 at 05:26 PM.
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Old 01-04-2013, 06:03 PM   #77
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thanks xluben. im gonna go back to yellow and no shim this weekend. i do get afterfire popping quite often now. did you special order the green spring??
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Old 01-04-2013, 06:09 PM   #78
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Quote:
Originally Posted by xluben View Post
Why would you use any of the heavier springs? Do you think you need to use a heavier spring to hold more boost? Because that is not true. The boost pressure holds the valve closed. You don't really even need a spring. The spring just controls how quickly/easily it opens when you let off. I always used the Green (special order) spring. Even running at 27-28psi peak boost.
I got horrible compressor surge with the red and blue, and even the yellow I'm not completely happy with, it's definitely not smooth. I'll see if I can find a green spring, find something else comparable, or maybe even try running without just because I'd like to see what happens.
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Old 01-04-2013, 07:22 PM   #79
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Yes I did order the green spring. The main thing I noticed with the heavier springs was audible surge/flutter. It is much more noticeable with certain intakes. With the stock air ox you may hear nothing but with a 3" intake it will be very obvious.

Running it with no spring does not work well. It needs a spring to produce some initial bias to get it to close. If you don't have a spring spool will be very late but eventually it will snap closed and you'll see full boost. I tried this to test my theory that a spring is not needed to hold high boost, and confirmed that thought but you do need to run it for normal use.
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Old 01-04-2013, 08:37 PM   #80
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If you don't have a spring spool will be very late but eventually it will snap closed and you'll see full boost.
That sounds like it's quite a kick in the pants if it's that abrupt
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Old 01-04-2013, 11:10 PM   #81
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Alright I got my Forge BPV in the mail today. I installed it using the blue spring (which came pre-installed). After a little bit of driving, I notice what sounds like a little compressor surge after lifting off the throttle (honestly, I dont know if that is the correct term; I am new to all of this ) I went ahead and switched to the yellow spring (per the Forge site, this is what I should be running). I am still getting a little bit of this "surge" when lifting off the throttle. I still have not gone full WOT since I want to make sure I haven't messed anything up with the install. Is this where the shims come into play? I dont think I should be running the red spring so I assume I just need to add some shims until the surge is gone. Is this a correct assumption? Based on some of the comments above, it looks like using a spring that is too stiff is bad. It also looks like I may need to special order the green one if none of the pre-packaged springs work. I apologize for asking in this thread, but I figured I would ask here instead of starting a new one.

BTW, I am running the TP Stage 1 map with Cobb intake. The map specifies for 18.5 PSI, but I see a lower PSI (about 17.5) due to my altitude. It looks like my intake makes the "surge" sound much more noticeable as previously mentioned but I would like to eliminate it if possible (it was not present with the stock BPV)

Last edited by CO11WRX; 01-04-2013 at 11:22 PM.
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Old 01-04-2013, 11:22 PM   #82
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If you have an intake then it's very common that you'd hear some flutter with a partial boost throttle lift, even with the yellow spring. But adding shims or going to a heavier spring will just make it worse. That is why I bought the green spring.

But if you just keep using the yellow spring ans using it as is won't really hiet anything. It will hold boost just fine and likely won't even flutter on full boost throttle lifts. So it's really just preference if you want to spend a few bucks on the green spring to reduce/eliminate the noise.
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Old 01-04-2013, 11:44 PM   #83
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I ordered a green spring from Forge this evening, curious to see if that takes care of it. I am getting flutter/surge even when lifting at full boost (20psi) with the yellow spring and I'm hoping this will be the end of that problem.
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Old 01-05-2013, 12:12 AM   #84
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Quote:
Originally Posted by xluben View Post
If you have an intake then it's very common that you'd hear some flutter with a partial boost throttle lift, even with the yellow spring. But adding shims or going to a heavier spring will just make it worse. That is why I bought the green spring.

But if you just keep using the yellow spring ans using it as is won't really hiet anything. It will hold boost just fine and likely won't even flutter on full boost throttle lifts. So it's really just preference if you want to spend a few bucks on the green spring to reduce/eliminate the noise.
Thank you! I think I will just stay with the yellow spring for now. My concern was the noise only started after I switched to the Forge. I could always just go back to the stocker but I am fairly certain it was starting to leave (I was getting a bunch of strange issues shortly after going stage 1). Those noises have now disappeared, but the fluttering just started. I think I will order the green as well just to try it out. Did you have to call Forge to order? I am looking at their site now but cannot find just a green spring (all I see are the "kits" which come with multiple springs)

here is an example (I am pretty sure this is the wrong part): http://www.forgemotorsport.com/conte...roduct=FMDVTUN
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Old 01-05-2013, 12:18 AM   #85
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There is an option on the site to buy individual springs, though it's not listed of you choose Impreza parts, you just look under their BOV/BPVs. It's 8$ for the spring and then whatever shipping from the UK is, which I'm not excited to find out the cost of.
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Old 01-05-2013, 12:29 AM   #86
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Quote:
Originally Posted by ResidentR View Post
There is an option on the site to buy individual springs, though it's not listed of you choose Impreza parts, you just look under their BOV/BPVs. It's 8$ for the spring and then whatever shipping from the UK is, which I'm not excited to find out the cost of.
Hmm thats strange. I am looking under the BOV/Recir Dump Valve Internals section of their site but I dont see any single spring options available. I think I will give them a call on Monday to see if they can shoot one out to me.
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Old 01-05-2013, 02:39 AM   #87
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Hmm thats strange. I am looking under the BOV/Recir Dump Valve Internals section of their site but I dont see any single spring options available. I think I will give them a call on Monday to see if they can shoot one out to me.
http://www.forgemotorsport.com/conte...duct=FMDVSU110
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Old 01-05-2013, 07:48 AM   #88
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Thats weird i have the green spring that came with mine and no red i didnt know it was a special order spring.
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Old 01-05-2013, 04:29 PM   #89
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Originally Posted by ResidentR View Post
Wow, I'm an idiot lol! I was looking at this exact same link, but because I saw all three springs in the pic, I assumed you had to buy all three (I was looking for just the green one). Sure enough, I completely missed the Options box where you can select the specific spring. Thank you for the link!

On another note, I drove quite a bit today with the Forge installed. It definitely got rid of some of the noises I was hearing with the stocker, but it also seems to have created some new noises. I bet they are most likely normal sounds. I took a datalog a few hours ago and sent it to Eric at TP so I will wait to see what he says before calling everything good. I was able to confirm that the surge/flutter only happens at partial throttle (I can consistently get it to appear when in 3rd gear). I found that if I gently let off the throttle between shifts the sound disappears (as opposed to abruptly releasing throttle). I dont hear the surge/flutter at WOT so I think I am good. A quick glance over my logs didn't show anything unusual (I am still learning how to read logs however). I'll post back once I hear back from Eric. Thanks again for the help everyone!
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Old 01-05-2013, 04:32 PM   #90
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is a retune needed when you replace the stock bpv?
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Old 01-05-2013, 04:48 PM   #91
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No tune needed. Just make sure the spring tension is appropriate for your boost levels.
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Old 01-05-2013, 04:56 PM   #92
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is a retune needed when you replace the stock bpv?
I'm still pretty new to all of this, but I was told to just make sure you replace the stocker with a BPV and NOT a BOV. As long as you do that, no tune is needed from what I have been told.
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Old 01-05-2013, 09:04 PM   #93
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Originally Posted by CO11WRX View Post
I'm still pretty new to all of this, but I was told to just make sure you replace the stocker with a BPV and NOT a BOV. As long as you do that, no tune is needed from what I have been told.
from what ive seen, a bov cant be tuned for and a car will run poorly regardless. a good bpv that is 100% recirculating is the best for the engine.
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Old 01-05-2013, 09:35 PM   #94
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I received an email from Eric/TP a few hours ago. He said everything in my logs looked great (he did not see any indication of leaks). The car seems strong as well.
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Old 01-06-2013, 12:08 AM   #95
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I went ahead and ordered the green spring from Forge's site. The spring was only $8 but it says shipping should be around $15 to the U.S. (it actually doesnt tell you how much shipping will be at the time of checkout, but there is an option to be notified if shipping is more than $15). Their disclaimer also mentions something about a customs tax which could be up to 40% of the order depending on the destination country. For those who have ordered the green spring from Forge, how much did you get charged for the customs fee?
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Old 01-06-2013, 12:30 AM   #96
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What boost levels are you running? I had Eric's tuen for my 08 w/ VF52 and ran the Yellow spring with 1 shim and didn't have any issues with surge or anything. The flutter sound while building boost is normal with the 52's. It's especially audible with an intake and aftermarket intercooler
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Old 01-06-2013, 12:49 AM   #97
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Originally Posted by Chaz2.5 View Post
What boost levels are you running? I had Eric's tuen for my 08 w/ VF52 and ran the Yellow spring with 1 shim and didn't have any issues with surge or anything. The flutter sound while building boost is normal with the 52's. It's especially audible with an intake and aftermarket intercooler
The TP Stage 1 map calls for 18 PSI of boost (I run a little less due to my altitude). I tried both the blue and yellow springs but still heard the flutter (as you mentioned, it seems to be a normal sound especially with an intake). I figured I would get the green just to try it out. If it doesn't make any difference, its only $8 for the spring (plus the $15 shipping). I figured I would try it just to see how things work.

EDIT: TP stage 1 calls for 18 PSI, not 18.5

Last edited by CO11WRX; 01-06-2013 at 01:02 AM.
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Old 01-06-2013, 07:14 AM   #98
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I don't know how many times I can say this but the spring does not depend on what boost level you run! You really just want the lightest one for the best response.

EDIT: but running the yellow with a little audible flutter is perfectly fine.
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Old 01-06-2013, 08:01 PM   #99
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threw my yellow spring in today and removed the shim. gonna leave it softer as per xlubens advice.
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Old 01-06-2013, 10:31 PM   #100
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Quote:
Originally Posted by xluben View Post
I don't know how many times I can say this but the spring does not depend on what boost level you run! You really just want the lightest one for the best response.

EDIT: but running the yellow with a little audible flutter is perfectly fine.
Thanks for the info! (I actually did notice your post about running the lightest spring possible, which is why I am going to try the green spring out). Thanks again (BTW, your car is bad ass!)
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