WRX and blow off valves

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.

Reply to
NitroTrike
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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

Reply to
Hallraker

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!!!!

Read these & weep!

Nige

Reply to
Nige

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

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

Reply to
Jim Stewart

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.

Sp>

Reply to
Spinifex

That's pretty good. Gold medal if I was the judge!

-Matt

Reply to
Hallraker

I like the "erector set" spoiler description. Just reading those words brought several Civics to mind that live near my house.

Reply to
Henry Paul

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.

Reply to
WRXtreme

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).

Reply to
Patrick Fisher

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

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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
Reply to
mike

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 "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

Reply to
Ken Gilbert

you might want to check this out:

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i've done it and it works a treat.

ken

Reply to
Ken Gilbert

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

Reply to
Hallraker

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.

Reply to
Henry Paul

Holy crap! That's too funny! =D

Reply to
JaySee

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