WRX and blow off valves

N

NitroTrike

Can someone PLEASE explain this. Why are these people, yes the ones that go
tearing by you, shift gears and make the "whoosh" noise, followed by a
backfire, doing this to their cars? Do they not realize that the atmo venting
BOV is sucking dirty air at idle, and not doing a damn thing for performance,
since the ecm is "looking" for the air that is supposed to be plumbed back into
the system. I cant believe what they pay for some of these things. Ive seen
many brands on Ebay, some costing as much as $300!. Well, hell if you want to
make a noise, run rich and backfire, just disconnect your return hose from your
stock BOV. These people tell me "the rally cars backfire". Well they also are a
"little" different than a stock engine and ecu, and they have engines at their
disposal. I had my ecm reflashed with EcuTek, and my tuner stressed the fact
that the ecm needs to "see" the air through the air meter. This function CANNOT
be compensated for with the reflash. EcuTek even recommends stock type
recurculating valve types. I just hope these people understand that
turbochargers dont like having backfires blown through them. But hey, to each
their own.
 
NitroTrike said:
Can someone PLEASE explain this. Why are these people, yes the ones that go
tearing by you, shift gears and make the "whoosh" noise, followed by a
backfire, doing this to their cars? Do they not realize that the atmo venting
BOV is sucking dirty air at idle, and not doing a damn thing for performance,
since the ecm is "looking" for the air that is supposed to be plumbed back into
the system. I cant believe what they pay for some of these things. Ive seen
many brands on Ebay, some costing as much as $300!. Well, hell if you want to
make a noise, run rich and backfire, just disconnect your return hose from your
stock BOV. These people tell me "the rally cars backfire". Well they also are a
"little" different than a stock engine and ecu, and they have engines at their
disposal. I had my ecm reflashed with EcuTek, and my tuner stressed the fact
that the ecm needs to "see" the air through the air meter. This function CANNOT
be compensated for with the reflash. EcuTek even recommends stock type
recurculating valve types. I just hope these people understand that
turbochargers dont like having backfires blown through them. But hey, to each
their own.
Click to expand...

To each their own indeed. I see all kinds of crazy shit on cars and frankly
nothing surprises me anymore. I could go on and on, but here are some
highlights I've seen over the years:

Chevy Cavalier with poorly fitted, primer colored, and partially bondo'ed
body kit. Melon launcher tailpipes, one of which was just hanging there and
not connected to anything. Gigantic rear wing, reminiscent of the ones
found on the previous generation Eclipse, only much larger. Half assed tint
job. Vanity license plate: "CAV2NV" Yeah, right. I might "NV" that if my
Outback exploded in the middle of the, um, Outback.

Another Chevy Cavalier, older one, with a boomin bass box and FOG lights
glued, taped, or screwed into the existing headlights. Yes, the mounting
brackets were rotated to face the rear and they were attached over the
existing headlight lenses. "Erector Set" style rear wing installed slightly
off-center. Another poor tint job. Do Cavaliers just come standard with
bad window tint?

Chevy Avalanche driven by 50-60 year old man, with "Erector Set" wing
attached to the rearmost bed cover piece. Yeah, I bet that bloated piece
needs a spoiler alright. It might actually hit 85.

And during the beginning of the blue headlight revolution, one young genius
covered the sealed beam halogens on his ancient VW with blue saran wrap.
I'm certain that increased light output by 500%.

And who could forget the endless barrage of Civics with melon launcher
tailpipes that run so rich they practically spew out liquid fuel. I've seen
some of them with Subaru hood scoops as well. Not sure where they get them
or why they put them on, but at least one person from this NG reported his
scoop being stolen a while ago.

-Matt
 
Hallraker said:
are a



To each their own indeed. I see all kinds of crazy shit on cars and frankly
nothing surprises me anymore. I could go on and on, but here are some
highlights I've seen over the years:

Chevy Cavalier with poorly fitted, primer colored, and partially bondo'ed
body kit. Melon launcher tailpipes, one of which was just hanging there and
not connected to anything. Gigantic rear wing, reminiscent of the ones
found on the previous generation Eclipse, only much larger. Half assed tint
job. Vanity license plate: "CAV2NV" Yeah, right. I might "NV" that if my
Outback exploded in the middle of the, um, Outback.

Another Chevy Cavalier, older one, with a boomin bass box and FOG lights
glued, taped, or screwed into the existing headlights. Yes, the mounting
brackets were rotated to face the rear and they were attached over the
existing headlight lenses. "Erector Set" style rear wing installed slightly
off-center. Another poor tint job. Do Cavaliers just come standard with
bad window tint?

Chevy Avalanche driven by 50-60 year old man, with "Erector Set" wing
attached to the rearmost bed cover piece. Yeah, I bet that bloated piece
needs a spoiler alright. It might actually hit 85.

And during the beginning of the blue headlight revolution, one young genius
covered the sealed beam halogens on his ancient VW with blue saran wrap.
I'm certain that increased light output by 500%.

And who could forget the endless barrage of Civics with melon launcher
tailpipes that run so rich they practically spew out liquid fuel. I've seen
some of them with Subaru hood scoops as well. Not sure where they get them
or why they put them on, but at least one person from this NG reported his
scoop being stolen a while ago.
Click to expand...

My favorite spoiler picture, shot in the parking
lot at work:

http://www.maceranch.com/images/spoiler.jpg

I'm actually considering registering stupidspoilers.com
and starting a web site for them.
 
HA HA HA

I agree... the things people do to their cars for appearance or sound
value, rather than performance!!!

One thing I CANNOT stand... is the plethora of Hyundai Excel's and
Accents and other assorted cheap, small hatches..... all running around
Australian cities with WRX bonnet scoops!!!

What possible value can this scoop serve, on a sub-2Litre NA motor.
Engine cooling??? I think not.... the majority of these are just
attached to the bonnet... without actually cutting the airflow hole.

Spinifex
 
I am in Australia, and I have fitted a WRX bonnet scoop to my Toyota Hilux
truck - see http://www.users.bigpond.com/dcoggins/pix/truckscoop.jpg

It looks like a giant wank - however, I have a 2.4 L turbo diesel engine in
the Toyota, and I have fitted an intercooler from a Mitsubishi Delica. I
also re-routed the air intake into the scoop to get cool air direct into the
intake.

It actually works very well!! The WRX scoop was the biggest I could I find
locally - I wanted maximum air intake. I use the truck for heavy towing work
around Queensland, and it runs heaps cooler with the scoop, so it was well
worthwhile.

I also own a 2000 Forester GT as well, so both vehicles have matching bonnet
scoops!! ( minor wank!!)

Dave
 
I like the "erector set" spoiler description. Just reading those words
brought several Civics to mind that live near my house.
 
NitroTrike said:
Can someone PLEASE explain this. Why are these people, yes the ones that
go
tearing by you, shift gears and make the "whoosh" noise, followed by a
backfire, doing this to their cars? Do they not realize that the atmo
venting
BOV is sucking dirty air at idle, and not doing a damn thing for
performance,
since the ecm is "looking" for the air that is supposed to be plumbed back
into
the system. I cant believe what they pay for some of these things. Ive
seen
many brands on Ebay, some costing as much as $300!. Well, hell if you want
to
make a noise, run rich and backfire, just disconnect your return hose from
your
stock BOV. These people tell me "the rally cars backfire". Well they also
are a
"little" different than a stock engine and ecu, and they have engines at
their
disposal. I had my ecm reflashed with EcuTek, and my tuner stressed the
fact
that the ecm needs to "see" the air through the air meter. This function
CANNOT
be compensated for with the reflash. EcuTek even recommends stock type
recurculating valve types. I just hope these people understand that
turbochargers dont like having backfires blown through them. But hey, to
each
their own.
Click to expand...

Simple answer why "I" run a atmospheric venting BOV: The stock one doesn't
hold boost well above 19psi and the Greddy Type-S that I had was HORRIBLE.

Reason for backfiring...probably due to the lack of catalytic converters.

"Well, hell if you want to make a noise, run rich and backfire, just
disconnect your return hose from your stock BOV."
-----Not if you want your car to run, the stock unit does not work correctly
if you remove the hose, it WILL sputter and not run well at all, do a search
on NASIOC about it.
 
WRXtreme said:
Simple answer why "I" run a atmospheric venting BOV: The stock one doesn't
hold boost well above 19psi and the Greddy Type-S that I had was HORRIBLE.

Reason for backfiring...probably due to the lack of catalytic converters.

"Well, hell if you want to make a noise, run rich and backfire, just
disconnect your return hose from your stock BOV."
-----Not if you want your car to run, the stock unit does not work correctly
if you remove the hose, it WILL sputter and not run well at all, do a search
on NASIOC about it.
Click to expand...

What he said. I'm looking for a decent BPV though, to replace the BOV.
Just a little too much noise for me (as if the exhaust wasn't loud enough).
 
I tried but I couldn't help myself I'll just add my 5 cents worth

Firstly the factory BOV cannot be used to vent to atmosphere UNLESS you add
a non-return valve to the outlet end (and plug the return pipe). This is
because the factory BOV only closes just below atmospheric pressure, i.e.
the valve is open at idle and when you are cruising(no boost). So in this
case air will be getting in through the BOV bypassing the MAF and hence
screwing up the ECU. Your car will run lean and will likely do some damage.

Secondly the aftermarket BOVs that vent to atmosphere do NOT have the same
problem as described above(assuming you have adjusted it properly) - they
close when the pressure after the turbo(but before the throttle) has reached
just slightly higher than atmospheric (assuming you have adjusted it
properly) so no 'dirty' air can get in. The reason the car backfires is
simple the ECU sees alot of air going through the MAF so it pump alot of
fuel to maintain what it believes is the right air-fuel mixture it has no
idea that a whole heap of air has been vented and won't be entering the
cylinder. So what happens? - a heap of fuel is pumped into the cylinder but
not all of is burned due to the lack of air. So a mixture of hot,
ready-to-pop fuel and exhaust gasses flow down your exhaust pipe until it
finds some air (more specifically 02) and explodes. Where it does this
depends on conditions; it could be as soon as the exhaust valve opens all
the way to the tip (well almost).
IF you want to prevent this either leave your factory BOV alone or get a
hybrid plumb-back/atmosphere venting BOV. The hybrids are not as noisy as
pure atmosphere venting valves but prevent backfiring by allowing enough air
back to prevent excessively rich mixture.

I have a hybrid one from http://www.gfb.com.au/ but its not installed - my
wife won't let me have the TOV (Toss-Off Valve as she likes to call it) its
a relic from my bachelor days.

Mike
96 Legacy GTB
 
Can someone PLEASE explain this. Why are these people, yes the ones that go
tearing by you, shift gears and make the "whoosh" noise, followed by a
backfire, doing this to their cars? Do they not realize that the atmo venting
BOV is sucking dirty air at idle, and not doing a damn thing for performance,
since the ecm is "looking" for the air that is supposed to be plumbed back
Click to expand...

you do know that a properly functioning BOV is a one-way device? as
in, air out, but not air in?

iow, there's no way to get dirty air sucked into your engine with a
properly sorted BOV.

into
the system. I cant believe what they pay for some of these things. Ive seen
many brands on Ebay, some costing as much as $300!. Well, hell if you want to
make a noise, run rich and backfire, just disconnect your return hose from your
stock BOV. These people tell me "the rally cars backfire". Well they also are a
"little" different than a stock engine and ecu, and they have engines at their
disposal. I had my ecm reflashed with EcuTek, and my tuner stressed the fact
that the ecm needs to "see" the air through the air meter. This function CANNOT
be compensated for with the reflash. EcuTek even recommends stock type
recurculating valve types. I just hope these people understand that
turbochargers dont like having backfires blown through them. But hey, to each
their own.
Click to expand...

the "backfire" (actually afterfire) does not occur in the manfold.
the combustion process cannot occur becuase it is FAR too rich to
"light off." the afterfire comes further down the exhaust pipe once
the rich mixture hits leaner air.

fwiw, i have a turboxs rfl bov, and i put it on from time to time.
the rest of the time i run a modified oem bpv. variety is the spice
of life, and it's educational to get real-time audio feedback on the
pressure differential across your throttle body (which is what
actuates bovs). it may be annoying and juvenile, but it IS fun (at
least for a little while), and it DOES NOT hurt your car to run rich
for a fraction of a second between shifts.

hth
ken
 
Henry Paul said:
I like the "erector set" spoiler description. Just reading those words
brought several Civics to mind that live near my house.
Click to expand...

I'm not actually sure which one of the people in my circle of friends came
up with that one, but I know most of us had those toy construction sets. I
think they were around well into the 1980's but after that I never saw them
again. If you look at those cheesy metal spoilers they've got holes drilled
in the vertical pieces that remind me a lot of the metal brackets and things
from those toys.

-Matt
 
Yeah that's exactly what I was thinking of. I thought if I was going to add
a spoiler I would at least make it look good.

My brother-in-law got an Erector set for his b-day on Labor Day. I didn't
know they were still around either.
 

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