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#21 Caine

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Posted 07 June 2008 - 05:44 PM

Most stock CBV/BOV/BPV or whatever you desire to call them are designed to only allow certain boost pressures to be effectively vented (or recirculated). Yes, you can run more than stock boost with MOST BOV. But, not everyone factory part always operates the same. Additionally, with some modifications, you may end up with more pressure or volume to be vented.

In as far as a BOV being a performance part in the in INCREASES your performance... it is NOT. What it DOES do is PREVENT you from losing power due to turbo surge and it allows the turbo to maintain it's rotational momentum. This can be seen by some as an increase in performance, when it is actually a prevention of LOSING power and losing spool.

A case in point, I was specifically having problems with my STI. When I would shift at redline (no matter how I shifted) when I put in the clutch my engine would rev higher due to my BPV not venting enough volume at a high enough rate. The pressure was still being maintained even with the BPV recirculating because I was running 4# more than stock boost. The BPV for THAT car was specifically designed to operate at stock boost levels. Now, with a hybrid BOV/BPV my car is much happier and it makes that funny pffffffffff noise, no whistle though.

Regarding the benefits of RECIRC versus BLOWOFF, with MAF cars ALL of the air that enters gets metered and there WILL be an appropriate amount of FUEL sprayed into the cylinder. If you completely VENT all of that air that was metered with a BOV, you will run rich for a short time when you lift AND you car will likely backfire. With a BPV, all of that metered air is retained in the intake system and there are no richness/backfire issues. All car companies AFAIK use the recirc method on their stock engines.

Personally, I used a hybrid BOV/BPV. It has TWO openings after the valve. The one that sees pressure FIRST is a recirc line connected like the stock recirc fitting, BUT there is also a blowoff (vent to atmosphere) port as well that sees pressure after part of the air is recirced. After a full throttle lift, both ports are opened almost simultaneously and the air (for this application) is split about 50/50.

That's all I got to say about that.

#22 Auburn T5

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Posted 16 July 2008 - 02:49 AM

QUOTE (Caine @ Jun 7 2008, 12:44 PM) <{POST_SNAPBACK}>

Personally, I used a hybrid BOV/BPV. It has TWO openings after the valve. The one that sees pressure FIRST is a recirc line connected like the stock recirc fitting, BUT there is also a blowoff (vent to atmosphere) port as well that sees pressure after part of the air is recirced. After a full throttle lift, both ports are opened almost simultaneously and the air (for this application) is split about 50/50.

That's all I got to say about that.

which one do you use?

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#23 Julien R

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Posted 26 July 2008 - 09:58 PM

Yo'all are funny!! even to a guy who is not mechanically inclined!

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#24 supra_stephe

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Posted 27 August 2008 - 02:30 AM

wait what is the difference between a CBV and an internal waste gate, and a normal by-pass valve?

#25 socal850tuner

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Posted 27 August 2008 - 02:39 AM

QUOTE (supra_stephe @ Aug 26 2008, 07:30 PM) <{POST_SNAPBACK}>

wait what is the difference between a CBV and an internal waste gate, and a normal by-pass valve?

cbv lets air that is being pushed into the engine out into the atmosphere. The wastegate lets go of exhaust gases. Two similar systems but do different things

'97 850 T5; K&N cone filter, IPD Sway Bars, Powerslot Slotted Discs, Strut Brace, IPD Poly upper engine mount, Voodoo mbc, MSD Blaster SS, Magnecor Spark plug Wires, Autometer Boost gauge on A-pillar, Pioneer Head unit, pioneer 5 1/4" up front and pioneer 6"x9" in the back, Rockford 450w amp, ~600 MTX 10" Sub, pioneer back door speakers, and 3.5"clarions in the dash

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#26 TBM

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Posted 15 September 2008 - 10:52 AM

QUOTE (Caine @ Jun 7 2008, 01:44 PM) <{POST_SNAPBACK}>

Regarding the benefits of RECIRC versus BLOWOFF, with MAF cars ALL of the air that enters gets metered and there WILL be an appropriate amount of FUEL sprayed into the cylinder. If you completely VENT all of that air that was metered with a BOV, you will run rich for a short time when you lift AND you car will likely backfire. With a BPV, all of that metered air is retained in the intake system and there are no richness/backfire issues. All car companies AFAIK use the recirc method on their stock engines.

I installed an HKS SSQV bov a couple of days ago and I vented fully a couple of times...each time I heard a loud POP as the RPM's reached idle. Did a search and my question was answered in this recent post.

How bad is this short period of running rich for the car? Any potential damage to anything?

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#27 blown_volvo850r

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Posted 18 September 2008 - 12:18 AM

*Loud* BOVs are better than CBVs because they can be used to scare old crabby women on the sidewalk.

Performance-wise, a properly working CBV that reroutes air to the intake (on a MAF based car like Volvos) is better than a BOV that vents to atmosphere. BOVs are for sounding cool, but if it makes you happier with your car, by all means get one. I'm on my third and I will never switch back to a stock CBV.

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#28 tozovr

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Posted 30 September 2008 - 09:46 PM

QUOTE (TBM @ Sep 15 2008, 06:52 AM) <{POST_SNAPBACK}>

Rich is better than lean!

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#29 cr854r

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Posted 07 October 2008 - 04:22 PM

QUOTE (exexpat @ Jan 7 2008, 11:06 PM) <{POST_SNAPBACK}>

BOV's are stupid and belong in my cosmetic forum, exactly like how all wheels/tire changes ever are only for cosmetic reasons.

Tire changes are one of the most important performance upgrades you can do

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#30 kildea

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Posted 08 October 2008 - 04:14 PM

QUOTE (tozovr @ Sep 30 2008, 10:46 PM) <{POST_SNAPBACK}>

Rich is better than lean!

ummm ...off throttle?

not so much.
i think you may be missing the barn door to mix a bit.

5 + 1 =

#31 S8ET6

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Posted 08 October 2008 - 04:40 PM

QUOTE (Che_Moderator @ Jan 3 2008, 02:04 PM) <{POST_SNAPBACK}>

CBV Job: Protect the Turbo From Surge
BOV Job: Protect the Turbo From Surge

So... all the Iraqis needed to do to defeat the Surge was throw BOVs and CBVs at our troops?

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#32 tozovr

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Posted 08 October 2008 - 04:56 PM

QUOTE (kildea @ Oct 8 2008, 12:14 PM) <{POST_SNAPBACK}>

ummm ...off throttle?

not so much.
i think you may be missing the barn door to mix a bit.

Off throttle is the point not moot? Regardless, My statement should have said "Richer is safer"

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#33 kildea

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Posted 08 October 2008 - 05:19 PM

QUOTE (tozovr @ Oct 8 2008, 05:56 PM) <{POST_SNAPBACK}>

Off throttle is the point not moot? Regardless, My statement should have said "Richer is safer"

not moot, you just are thinking we're talking about it getting rich on-throttle ..... the problem with rich spikes, due to bov's, occurs when you let off of the throttle.

so ... off-throttle, where you want it to be lean, you know?

there is no ping/detonation safety issue here.

5 + 1 =

#34 Wagon Mafia

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Posted 08 October 2008 - 05:38 PM

but they sound so cool!

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#35 tozovr

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Posted 08 October 2008 - 06:51 PM

QUOTE (kildea @ Oct 8 2008, 01:19 PM) <{POST_SNAPBACK}>

When it runs momentarily rich, off throttle how is it bad? I'm not arguing, I'm interested in the answer.

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#36 kildea

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Posted 08 October 2008 - 07:03 PM

QUOTE (tozovr @ Oct 8 2008, 06:51 PM) <{POST_SNAPBACK}>

When it runs momentarily rich, off throttle how is it bad? I'm not arguing, I'm interested in the answer.

well, i don't think it's that big of a deal for people, some have problems with driveability and stalling, i think it depends on the ecu, tune, and injectors.
lh2.4 with the big cfi's will stall on you if the engine dumps several liters of air that it is expecting to pass through, and so injecting a bunch of fuel for.

but i think the biggest concern is just the exhaust equipment, not so good for your cat if it happens all the time.

5 + 1 =

#37 EricF

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Posted 08 October 2008 - 08:28 PM

QUOTE (tozovr @ Oct 8 2008, 02:51 PM) <{POST_SNAPBACK}>

When it runs momentarily rich, off throttle how is it bad? I'm not arguing, I'm interested in the answer.

Depending on your tune you may have a little hesitation if you try to get right back on the gas. It's not that it's *bad* per se, it's just that lean is the proper and normal condition at that point. Decel AFRs with the throttle closed are usually off the scale of most wideband air/fuel gauges I've seen, i.e. over 40:1 or so.

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#38 johnloves850's

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Posted 13 December 2008 - 02:55 AM

QUOTE (v4lve @ Jan 21 2008, 08:13 PM) <{POST_SNAPBACK}>

wow you guys must hate mk4 vw shows

vw's are for loosers
no one that has a vw is an individualist
they all follow the crowd and listen to lil wayne

KoolAidKid, on 22 October 2009 - 01:32 PM, said:

We need a VSJr.com for this kind of shit though. A place where Cato, Noonan, johnloves850's, Hastings...and all the other youngin's can ask there ridiculous questions.

John: 1997 volvo 854 t5 (red)

#39 swedeseed850

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Posted 27 January 2009 - 04:09 AM

OK, so without being a total a s s about it, can you solve a quarrel for me, if you do install a BOV on your 850, which hose is the best place to install it? the front most area, or the rear aluminum pipe? Ive had it both ways, its on the aluminum one now, and yes, it has enough ponies, and so what, its an automatic with the TCM custom flashed. Believe me, it flies like a fiver, but the five speed conversion is on the way. I'm serious about my question, so please, have mercy.

#40 nolanator

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Posted 27 January 2009 - 04:11 AM

QUOTE (swedeseed850 @ Jan 26 2009, 08:09 PM) <{POST_SNAPBACK}>

the closer to the throttle body the better. how'd you manage to build up "enough ponies" without knowing where to put a blowoff valve?

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Volvospeed Forums: Blowoff Valve Threads - Volvospeed Forums

Blowoff Valve Threads Rate Topic: 1 Votes

#21 Caine

#22 Auburn T5

#23 Julien R

#24 supra_stephe

#25 socal850tuner

#26 TBM

#27 blown_volvo850r

#28 tozovr

#29 cr854r

#30 kildea

#31 S8ET6

#32 tozovr

#33 kildea

#34 Wagon Mafia

#35 tozovr

#36 kildea

#37 EricF

#38 johnloves850's

#39 swedeseed850

#40 nolanator

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