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Experimenter
Tubaru Pickup
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3,910 Posts
Bov sounds normal, what's happening is at low load when you lift off throttle your not getting enough engine vacuum to pull back on the spring keeping valve closed. You can loosen until it's barely shut at idle, improve signal line, or just live with it. Our Borg's have 360 thrust bearings. A little compressor surge won't hurt it
 

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Premium Member
2001 Subaru Impreza L coupe
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766 Posts
Discussion Starter #883
Bov sounds normal, what's happening is at low load when you lift off throttle your not getting enough engine vacuum to pull back on the spring keeping valve closed. You can loosen until it's barely shut at idle, improve signal line, or just live with it. Our Borg's have 360 thrust bearings. A little compressor surge won't hurt it

Messed with it more the other day. It’s either open at idle with no flutter/surge, or lots of flutter/surge and still open just a little bit at idle.

It came with some shims and Turbosmart said to add 2-3 and see if that helps keep it shut at idle. Gonna try that and a new signal line. If it doesn’t work, I’ll just deal with it.

Shit I take longer than that to put them together. I need to pick it up :lol:

The only reason I get anything done is because I’m impatient. Also I can’t let the cars sit too long or nature starts to overtake them. Brakes completely seize up from rust, squirrels get into the engine bay, spiders everywhere, ect

I need a garage :lol:
 

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Registered
Turbo, LS swapped Impreza RS
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5,166 Posts
I've read a .250" reference line improves response over the standard .125" line.

Sent from my SM-N920V using Tapatalk
 

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Premium Member
2001 Subaru Impreza L coupe
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766 Posts
Discussion Starter #885
I've read a .250" reference line improves response over the standard .125" line.

Sent from my SM-N920V using Tapatalk

I’m like 98% sure the factory line from the manifold to the bov is 1/4” (0.250”).

My boost gauge is still tee’d off that line but I can’t really see that being an issue.
 

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Experimenter
Tubaru Pickup
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3,910 Posts
I added washers to mine since it wasnt adjustable. During my 30psi leak test i could hear some air leak at the BOV valve. More pressure holds in more air but makes it harder for lil vacuum line to open it
 

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Premium Member
2001 Subaru Impreza L coupe
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766 Posts
Discussion Starter #887
Tried the washers, didn’t really work like I needed. They just changed how loose the adjustment cap needed to be. More washers=looser cap.

3 washers was too much. I would get a ton of flutter/surge unless the adjustment cap was loosened pretty much all the way to the o-ring.

2 washers was better but still too much surge.

Currently on 1 washer and it’s ok, and might end up taking it back out and using no washers. Right now there’s almost no surge, but the piston is still open a little at idle.

I’ve concluded that there’s no way to have it be fully closed at idle and have no surge. Something about my setup and/or this BOV that won’t let it work 100% correctly. So I’ll have to deal with the piston being slightly cracked open at idle. Shouldn’t effect me in speed density but still annoying
 

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Registered
Turbo, LS swapped Impreza RS
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That's interesting that there is no happy medium Did you get in touch with the manufacturer? I'm now curious how mine will act, especially with two.
 

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Premium Member
2001 Subaru Impreza L coupe
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766 Posts
Discussion Starter #889
That's interesting that there is no happy medium Did you get in touch with the manufacturer? I'm now curious how mine will act, especially with two.

Yea Turbosmart said to try the washers. I called again today and they think it’s possibly an airflow issue, not an adjustment issue.

It’s one of their “dual ports” that can be ran in 100% VTA, 100% recirc, or 50/50. Obviously mine is setup for 100% VTA. There’s a blockoff plate for the recirc side, and they told me to take it off and see how it acts with both sides open. Not meant to be a permanent solution, but only to see if the flutter/surge goes away with the BOV having another side to vent from.

They said if it works better with both sides open, the BOV is likely too small or not the right style for what I need.
 

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Premium Member
2001 Subaru Impreza L coupe
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766 Posts
Discussion Starter #890 (Edited)
Finally got around to messing with the stupid BOV, and I need a different one. It’s too small.

Removed the blockoff plate so both outlet ports are open. No surge at all and the piston can stay closed better. The “inlet” side of the BOV is smaller than the factory BPV.....by atleast 1/16”. So I think it’s a combination of the inlet being too small and the outlet too small as well.

So I need to get one with a larger inlet/outlet combo but I’m trying to decide on the flange type. Really don’t feel like re-doing my charge pipe just to change the BOV.

Annoying.
 

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Premium Member
2001 Subaru Impreza L coupe
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766 Posts
Discussion Starter #892
The joys of custom stuff

Yea my fault for not looking into stuff enough

Original plan was to run this turbo in MAF or hybrid mode at first, and just keep using the factory BPV. But it was a lot easier just to switch to SD, so I quickly found a BOV that would attach right to my charge pipe like the factory BPV did. Just didn’t realize it was small.

So I got a new BOV with larger piston size on the way. Should be here today. Hoping that fixes my surge issues. Then I can get into the higher rpm stuff for my VE table, and finally start adding more boost.

—————


I made a new up pipe bracket. The factory one was in the way of the oil return from the rotated turbo. The return hose would rest on the bracket and rub no matter how it was ran. It also made the angle on the hose a tighter, which is not ideal for good drainage.

So I got a new bracket and chopped it up. Welded some pieces on to restructure it around the hose. Still need to go back and add more bracing on the one tab. Hard to tell the difference, but the hose angle is much better and no rubbing. Not very pretty but it works.

No, it’s not touching the flange. Just looks close because of the picture.





And one thing I forgot to mention recently, is that I got a TIG. Was already sick of trying to MIG stainless and really wanted to be able to weld aluminum.

Still need more practice with it, but hopefully soon I can make a nicer downpipe, and re-do my fmic piping to eliminate most of the couplings. Fun messing around with it so far though

 

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Premium Member
2001 Subaru Impreza L coupe
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766 Posts
Discussion Starter #895
Did you go with a v-band setup?

Sent from my SM-N920V using Tapatalk


Yup. Once I re-do my charge pipe in aluminum I’ll weld the flange on.

For now, it’s just gonna be hose clamped to the tube coming off the fmic pipe. The weld-on flange it comes with doubles as a hose adapter, because it has a lip on the end so you can use a hose & clamp if needed. Kinda lame I know, but it’s only temporary.

Kinda see the lip here:



New on left.

You can see the difference in piston size. 1.5” compared to 1” on the other. Should let out air easier, hopefully preventing surge. The old one actually had a slightly smaller piston than the oem BPV. This should fix my issues.

Installed it yesterday but didn’t drive the car yet. Too lazy in the week. Will test today after work.



 

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Premium Member
2001 Subaru Impreza L coupe
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766 Posts
Discussion Starter #897
Did’t fix it.

Still getting surge.....but it’s different. I think this bov could work, should flow enough, but I’m 90% sure the spring is too heavy.....and this specific bov apparently only has 2 fucking spring options. Gonna do one more test to confirm.

Most likely will re-do that section of my intercooler piping to put on a different bov that WILL work, and reposition it to fit better. That will also get rid of the section that’s stainless and heavy.

Even have plenty of scraps left over that I can make it for free. Always a bonus:



Either way, while I work on that, I’m pushing on with the tune because I’m impatient.

First, I put on some nice silicone hoses for the wastegate/bcs lines to get rid of the sketchy clear vinyl ones I had on temporarily.





After more testing at 5-10 psi, I finally started adding boost. Up to 15 psi now. Taking it slow, carefully working my way up the VE table. Starting to get an idea of the curve it wants.

Boost/wgdc is controllable and predictable so far. EWG seems to react the same as the IWG. I had pretty good success with the last setup at 20 psi, so I did the same thing and started with a zero’d WGDC table. Start simple at first to hit targets, then adjust for spool later.

Video of 15 psi testing to show the boost gauge. More interesting than just posting a datalog. At 6,000 rpm it’s pulling 265-270 g/s. Not bad for 15 psi and low timing. 20+ should be fun. Just gonna limit myself to maxing out the stock map sensor until I can get a built block in the car.

01 Impreza L, Borg Warner s257sxe 15 psi test - YouTube
 

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Premium Member
2001 Subaru Impreza L coupe
Joined
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766 Posts
Discussion Starter #899
I’m kinda surprised how close the AFR’s are so far, but still wanna tighten them up a bit. Seems like I might need a tiny bit more VE around peak load, and less after 6,000 or so. Need to test more rpm and boost to see if the trend continues
 
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