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Old 01-26-2008, 04:17 PM   #1
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Default Stupid question...

What would happen if I ran the car w/o a bov? I've got an HKS Replica bov.. I know they release any left over pressure in the pipes... but having to recirculate it so it doesn't release it into the atmosphere since i'm using a MAF.
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Old 01-26-2008, 04:23 PM   #2
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what turbo/boost pressure?
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Old 01-26-2008, 05:50 PM   #3
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T25.. 5lbs if anything. I'm asking as a temporary setup. Until I tig up everything and finalize this setup
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Old 01-26-2008, 05:53 PM   #4
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its fine.
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Old 01-26-2008, 07:30 PM   #5
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Thanks buddy..
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Old 01-26-2008, 11:00 PM   #6
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Quote:
Originally Posted by fast View Post
Dont ask me ,but i heard it will spool qiucker with one..
:fm:
you fail
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Old 01-26-2008, 11:32 PM   #7
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I Fail...LOL I no for a fact it will spool better with one...Ask anyone who knows..you dont...I been 7's in the 1/4 mile,you haven't...It may have been a Bike ,but its 7's and have friends cars that I help with that have turbo's..Wanna Race??Its not free...
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Old 01-27-2008, 12:49 AM   #8
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wait so wut??? a turbo spools quicker w/ a blow-off valve???

btw pakman, what part of glendale u in?? im in glendale hahaha (well on my free time anyway, but i grew up there) im running w/o a bov at the moment and its just find for me i can hear some surge if i let off too quick, but if i let go gradually, then i dont hear anything
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Old 01-27-2008, 01:06 AM   #9
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Considering all a BOV does is release boost when the engine gets back into vacuum I don't see how it would make a turbo spool faster. The rate a turbo spools is determined by the output from the engine and the regulation of flow by the wastegate.
The only reason someone would see boost build faster with or without a BOV is if they had a leaking BOV bleeding boost off while they were trying to build up to peak boost. That still has nothing to do with how fast the turbo itself spools.

Now if you're running high boost without a BOV and you're running through the gears everytime you lift the throttle the turbo will surge. That surge will interfere with the turbo's ability to spool back up to peak boost while you run to redline in each gear.
For people running low boost it won't make that much of a difference.
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Old 01-27-2008, 01:25 AM   #10
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A BOV does not make a turbo spool quicker, it keeps it spooled between shifts. without a BOV, the compressed air backs up and causes the turbo to stop quickly, repeadly, because of the pressure. Thats compresor surge. not really a problem at 5psi, but its better to have the BOV.
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Old 01-27-2008, 01:37 AM   #11
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The bosche BOV recircs are almost free on ebay. But let me guess, you want to hear it!? Or get the bosche and one of those fake electric speaker things.
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Old 01-27-2008, 01:55 AM   #12
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Quote:
Originally Posted by fast View Post
I Fail...LOL I no for a fact it will spool better with one...Ask anyone who knows..you dont...I been 7's in the 1/4 mile,you haven't...It may have been a Bike ,but its 7's and have friends cars that I help with that have turbo's..Wanna Race??Its not free...
I've been Mach 1.3 in a Tomcat and you haven't, which must mean I know everything about turbocharging. And so I declare you fail the worst I've ever seen anybody fail on any subject ever.

We all know what happens when boost hits a closed throttle plate... it backs up in the charge pipe and slows turbine RPM. With a BOV venting that boost, the turbo can keep most of it's RPM, and when the throttle is opened, the turbine is spinning faster than it would be if there was no BOV. But when speaking of spool, this isn't really what "spool" is. At the most, a BOV prevents spool from being lost... but that's not the same as "spooling better" as it is typically spoken of.

fast, talking **** on your second post isn't advisable on any forum... let alone this one. If you want advice on turbocharging or supercharging your Miata, then head over to the BS forum and introduce yourself... otherwise go away.
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Old 01-27-2008, 01:55 AM   #13
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I ran for a good while with no bov at low boost it realy isn't a problem. The main job of the bov is to eleviate the pressure wave washing through the compressor backwards and wearing on your seals/bearings. Keeping the turbo closer to spooled is just a nice benefit.
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Old 01-27-2008, 04:22 AM   #14
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This is probably a stupid question. Will a recirculated BOV placed on the cold side cause lower charge temperatures, pre-intercooler since the intercooled air is mixed together w/ the non-intercooled air, and also doubly cooled? Probably insignificant, but just wondering.
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Old 01-27-2008, 04:33 AM   #15
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Totally insignificant, probably.
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Old 01-27-2008, 05:12 AM   #16
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Actualy since most FMIC's are putting your air at ambient best case scenario, a recirc would only serve to slightly elevate the temp, of your intake charge but not to the point where it would hurt unless you had a horribly inefecient IC.
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Old 01-27-2008, 06:54 AM   #17
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Quote:
Originally Posted by rotaryjunky View Post
The bosche BOV recircs are almost free on ebay. But let me guess, you want to hear it!? Or get the bosche and one of those fake electric speaker things.
Actually I don't want to hear it.. I might just go with a bosche. Where do you normallly recirculate it too? Before or after Turbo? Or is it anywhere after the MAF?
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Old 01-27-2008, 10:17 AM   #18
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Corky says it doesn't matter where you mount the BOV... either pre or post intercooler is fine. You recirculate it into the intake AFTER THE MAF but BEFORE THE TURBO. This has been discussed a lot... do a search.

As for sounds... you're gonna hear it. WOT shifting it's gonna be really noticeable, but it just sounds like a big whooosh with the Bosch. It doesn't go out of it's way to be F&F ricer retarded... and the Bosch's don't flutter. Just a big air rushing whoosh. The MAF will help dampen the noise somewhat. Mine got about 25% louder when I removed mine.

Here are pics of mine. Granted, I don't have a MAF, but imagine the filter is mounted to it insted of just the coupler. My BOV is a standard Bosch unit from a Saab, mounted about 1' down from the throttle body, and the hose is a 1" radiator hose that routes down below the crank pulley and back up into the intake about 5" before the turbo.
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