Recommend the best BOV for my boost levels. - Page 4 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 10-02-2014, 09:06 PM   #61
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Even with 30 psi the valve wont be opened at wot even on the softest spring. The pressure is even on both sides therefore the only thing the valve sees is the spring. 0 surge, small leak between 60-80kpa on my 2554 since it's partially spooled and i have replaced the secondary spring with an even softer spring.
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Old 10-07-2014, 07:34 PM   #62
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Got the new "green" main spring from Forge - yippee! Installed and test drove around the neighborhood...

First thing I have to say is the difference from an old China BOV to the Forge is AMAZING. Its like a whole new car! I'm at 0psi around 2000rpms, and no longer have to wait 2000rpms to get to max boost. Crazy different. It also sounds great, the sound is way meaner than the "pew pew pew" HKS's. I don't know why anyone buys a China BOV.

Only thing is... I still have plenty of compressor surge. This spring is supposed to be for 5-15PSI, but it really only opens when I'm full 9-point-something PSI of boost. Even when it opens, its only for a split second, then I get compressor surge again.

I understand it can be quite tough to get rid of every little ounce of surge, but at this point its not really safe to drive too much. Should I cut the spring? Heat the spring? Enlarge the holes? I kept the stock (I think softest) secondary spring in there, btw. Not sure where to go from here.
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Old 10-07-2014, 07:44 PM   #63
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It shouldn't open in boost, it should open in vacuum, when you let off your throttle. It should stay closed when in boost.
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Old 10-07-2014, 07:47 PM   #64
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where are you sourcing your signal from and how big is the line? maybe you already posted, I'm lazy lol
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Old 10-07-2014, 07:48 PM   #65
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Quote:
Originally Posted by Chiburbian View Post
It shouldn't open in boost, it should open in vacuum, when you let off your throttle. It should stay closed when in boost.
You know what I mean
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Old 10-07-2014, 07:50 PM   #66
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Quote:
Originally Posted by 18psi View Post
where are you sourcing your signal from and how big is the line? maybe you already posted, I'm lazy lol
Signal is coming off one of the throttle body nipples but is shared with the boost gauge. I think its 3/16th silicone hose? It some weird small size that someone recommended on here.
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Old 10-07-2014, 07:51 PM   #67
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that may be a problem (but I'm just guessing)

there's a reason tial and lots of others run really big ports on their bov's.
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Old 10-07-2014, 07:54 PM   #68
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how much vacuum does your boost gauge show?
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Old 10-07-2014, 07:55 PM   #69
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That would only be an issue from a response side of things. BOV doesn't vent through that little reference hose.

I use a 20+ year old HKS unit on the MX6 and the nipple is impossibly small. Doesn't hurt anything. Still surges (well really... it's unloaded compressor stall, so really not a big deal at all at low boost pressures) anything below 10psi, but that's how i had to adjust it to not eat **** at 25psi+.

Huge piston helps, too.
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Old 10-07-2014, 08:03 PM   #70
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Quote:
Originally Posted by Chiburbian View Post
how much vacuum does your boost gauge show?
Lots of vacuum. My gauge isn't super accurate (Chinese) so its more of a reference thing. I would have to check the log from my MS3 to see true data.

18psi - what size/location do you recommend for the BOV? I used this 3/16th stuff all over the place, wastegate too. I don't exactly see how larger hose would help, though. Wouldn't that technically mean LESS vacuum the larger you go?
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Old 10-07-2014, 08:06 PM   #71
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Quote:
Originally Posted by Ds1 View Post
Lots of vacuum. My gauge isn't super accurate (Chinese) so its more of a reference thing. I would have to check the log from my MS3 to see true data.

18psi - what size/location do you recommend for the BOV? I used this 3/16th stuff all over the place, wastegate too. I don't exactly see how larger hose would help, though. Wouldn't that technically mean LESS vacuum the larger you go?
No, wouldn't change that at all. In theory it might change response time, but in practice it's not super likely.

You aren't having a response problem anyways, from your description. You're having a "my **** doesn't vent" problem.

Is the unit adjustable at all?
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Old 10-07-2014, 08:09 PM   #72
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Quote:
Originally Posted by concealer404 View Post
That would only be an issue from a response side of things. BOV doesn't vent through that little reference hose.

I use a 20+ year old HKS unit on the MX6 and the nipple is impossibly small. Doesn't hurt anything. Still surges (well really... it's unloaded compressor stall, so really not a big deal at all at low boost pressures) anything below 10psi, but that's how i had to adjust it to not eat **** at 25psi+.

Huge piston helps, too.
except no

because on my '00 with a Forge bpv I used a vacuum line T with a restrictor in it, making the ID a lot smaller and got noticeable comp surge, replaced and all was fine. nothing else changed. the restrictor was small, but not microscopic, probably about half of the "normal" vacuum line ID.

I'm not saying that's for sure it. I'm saying its worth considering
Quote:
Originally Posted by Ds1 View Post
Lots of vacuum. My gauge isn't super accurate (Chinese) so its more of a reference thing. I would have to check the log from my MS3 to see true data.

18psi - what size/location do you recommend for the BOV? I used this 3/16th stuff all over the place, wastegate too. I don't exactly see how larger hose would help, though. Wouldn't that technically mean LESS vacuum the larger you go?
...umm
how do you know its at 9psi then
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Old 10-07-2014, 08:13 PM   #73
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Quote:
Originally Posted by 18psi View Post
except no

because on my '00 with a Forge bpv I used a vacuum line T with a restrictor in it, making the ID a lot smaller and got noticeable comp surge, replaced and all was fine. nothing else changed. the restrictor was small, but not microscopic, probably about half of the "normal" vacuum line ID.

I'm not saying that's for sure it. I'm saying its worth considering


You were getting surge due to response time. His **** is just straight up not opening until 9.whatever psi, according to his super accurate chinese gauge.

I'd say it's possible that maybe it's surging enough to dump pressure that by the time his slow responding valve would have gotten the memo, it's open, but unless he's put a restrictor in, himself, it's really unlikely to happen using 3/16" open line.


MOAR COMMAS, PLS
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Old 10-07-2014, 08:27 PM   #74
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Since you were saying that boost gauge was plumbed in the same place as BOV I don't care what your ECU says. What I was getting at was making sure that the place you were getting your signal actually sees vacuum.

If your boost gauge sees vacuum then it is probably an ok place to be plugged into BOV wise.
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Old 10-07-2014, 10:55 PM   #75
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The gauge is always the same, the numbers just don't fall in the correct place. When I am making about 9.5psi the gauge reads 11psi. Not too big of deal really.

Right. It's not a response thing. It's opening, just not as much as I need it to. The part that is weirdest to me is that it DOES open, but then must not vent enough air because I still get compressor surge even after it opens. Just a weaker spring, then?
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Old 10-08-2014, 01:35 AM   #76
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yes. try a softer spring.

I'm kinda surprised they didn't sent you like 3 or 4 springs like they do with most of their valves. Each valve I've owned from them, and I had like 4-5, all came with like 3-4 springs each
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Old 10-08-2014, 09:41 AM   #77
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I bought the -007P and it came with 3 springs. The double piston comes with one and they sell a kit of 4 springs separately.
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Old 10-08-2014, 11:20 AM   #78
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They don't make a softer spring. I'm on the green spring, which is the softest they make. I also have the yellow one which is the next step heavier and that's the one that wouldn't open at all.

That's why I was saying earlier if I should try to heat the spring or something to make it softer. I guess I'll have to give them a call too.
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Old 10-08-2014, 11:21 AM   #79
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I'd call them first and ask what the ****.
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Old 10-08-2014, 11:22 AM   #80
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There's got to be a problem. Either you have a defective valve, or something is up with your vacuum source.

The symptoms you're describing are just...not...normal.

change the vacuum source. it will take 2 seconds to do. run it off the back of the mani. report back.
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