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Old 04-11-2002, 01:47 PM   #1
Scooby Newbie
Member#: 4850
Join Date: Mar 2001
Location: Back to Boostin' in SLC!
1998 EJ22.5RS-T
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Default Bosch BOV = Junk?

All right whats the deal with this thing? It looks pretty cheesy to me so I was wondering if Im just better off getting an HKS/ Greddy BOV before I install my turbo kit and throw this thing in the trash. What do you guys think? I plan on running 5psi off a Garrett T3/T4 so you know. Thanks once again
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Old 04-11-2002, 01:53 PM   #2
Worst Mod Ever
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Join Date: Oct 1999
Chapter/Region: SWIC
Location: Phoenix, AZ
12 Vagon


I personally don't think they are made very well.

Last edited by AaronB; 08-24-2003 at 01:59 AM.
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Old 04-11-2002, 02:24 PM   #3
Frank Army
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Location: Phoenix, AZ
1999 Outback Sport
Steel Blue Mica


As Aaron stated, the Bosch has a tendency to leak, even @ idle... Most people will agree that this is one case where spending the money on a better BOV is worth it.... Just about anything is better, the stock WRX BOV is a good alternative as is the Greddy, HKS and GFB.
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Old 04-11-2002, 03:31 PM   #4
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2004 Forester XT
bug spattered


Guys, not all Bosch BOVs are junk. Just the one you're looking at. The Bosch on my old Saab SPG held over 20 psi without leaking.
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Old 04-11-2002, 04:53 PM   #5
Frank Army
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Join Date: May 2000
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Location: Phoenix, AZ
1999 Outback Sport
Steel Blue Mica


Porter is right as well... I don't want it to seem like we are bashing Bosch in general.... Just these 5psi BOVs... Wish I had the part number handy so we could reference that...
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Old 04-11-2002, 05:32 PM   #6
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2014 Audi S4


Yes don't buy it.
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Old 04-11-2002, 06:15 PM   #7
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Location: Sin City
1993 Impreza GCStyle


It's a bit of a debate if a BOV is even needed. For the most part, they are put on by auto makers to help make the car more quite.

If the Bosch is really junk, then why would Porsche put them on 400+ hp turbo Porsches?

Personally, I think all the fancy BOV's like the HKS SSBOV for example is a waste of money UNLESS bought for cosmetic reasons. Can anyone truely explain WHY the expensive BOV's are so much better? I can understand if it leaked under boost, but how do you know it's leaking??? Do you have a boost gauge installed in the line coming off your BOV?

93 1.8T with a Bosch BOV
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Old 04-11-2002, 09:34 PM   #8
Scoobie Steve
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1998 11.87@112mph
Subaru L Ver 6 STi Type R


AaronB at idle(High Vacuum) the Bosch BOV is wide open so it will (leak) but as soon as you hit the gas and the vacuum goes to 0 it will close and as boost pressure comes on it will help to hold it shut. I've run mine up to 14 psi with NO leaking and for the price it cant be beat! Although finding a good used one in the junkyard is hard(Diaphram always shot) so maybe the longevity of the Bosch unit isnt great.
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Old 04-11-2002, 10:22 PM   #9
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Join Date: Jun 2000
Location: Austin, TX
2008 STI


I don't know what Bosch BOV you are using, but the one I recommend is factory on a Porsche 993 (I think). In researching the cheap BOV's, many of the cheap Boschs are junk. You just need to be careful which you get as they can all look the same but all be very different. Sorry, I don't have the links to what's good and not but here is the part number for the Porsche part number: part # 993-110-337-5. Price is a whopping $33 brand new.

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Old 08-23-2003, 09:40 AM   #10
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This thread came up in a search, very funny stuff, it's a good thing it's old, I'd hope a few people have found out the diffrence between a BOV and a CBV since then.

"Leaks at idle", I read that and just about wet myself.
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Old 08-23-2003, 03:27 PM   #11
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2001 2.5rs-t
silverthorn metallic


What would happen if your bov was leaking under boost?

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Old 08-24-2003, 07:36 AM   #12
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1998 Red Wagon
New Turbo Project...


On a MAF based car with a recirculative BOV or "CBV" you'll just lose boost pressure and idle fine.

On a MAF based car with a open BOV you'll have incorrect MAF readings and it will idle for crap.

On a MAP based car you'll also just lose boost pressure but the idle will be fine.


PS. I'm still not sure what point Bishop74 was trying to make, some important points were brought up in this thread. Regardless or whether its an open BOV or closed BOV (aka CBV, a term NOBODY uses around here) leaking at idle is not an ideal thing.
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