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 Blowoff valve

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jai
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PostSubject: Blowoff valve   Tue 03 Nov 2009, 00:38

Definitions

A compressor bypass valve (CBV), also known as a compressor relief valve or diverter valve, is a vacuum-actuated valve designed to release pressure in the intake system of a turbocharged car when the throttle is lifted or closed. This air pressure is re-circulated back into the non-pressurized end of the intake (before the turbo) but after the mass airflow sensor.
A blowoff valve, (BOV, sometimes hooter valve, not to be confused with a dump valve) performs the same task but releases the air into the atmosphere instead of recirculating it. The blowoff action produces a range of distinctive hissing sounds, depending on the exit design. Some blowoff valves are sold with a trumpet shaped exit that intentionally amplifies the sound. The TurboXS model RFL blow off valve is well known among tuners for this kind of design and some turbocharged vehicle owners may purchase a blowoff valve solely for the auditory effect even when the function is not required by normal engine operation. Motor sports governed by the FIA have made it illegal to vent unmuffled blowoff valves to the atmosphere. In the United States, Australia and parts of Europe cars featuring unmuffled blowoff valves are illegal for street use.[citation needed]
Blowoff valves are used to prevent compressor surge, a phenomenon that readily occurs when lifting off the throttle of an unvented, turbocharged engine. When the throttle plate on a turbocharged engine closes, the high pressure air in the intake system is trapped by the throttle and a pressure wave is forced back into the compressor. The compressor wheel slows rapidly and may even stall, and the driver will notice a fluttering air sound. The rapid slowing or stalling stresses the turbo and imparts severe turbo lag if the driver accelerates immediately after the surge event.
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jai
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PostSubject: Re: Blowoff valve   Tue 03 Nov 2009, 00:38

Disadvantages

In the case where a mass airflow sensor is used and must be located prior to the blowoff valve, the engine control unit (ECU) will meter out excess fuel because the atmospherically vented air is not subtracted from the intake charge measurements. The engine then briefly operates with a fuel-rich mixture after each valve actuation.
The rich mixing can lead to hesitation or even stalling of the engine when the throttle is closed, a situation that worsens with higher boost pressures. Occasional events of this type may be only a nuisance, but frequent events can eventually foul the spark plugs and destroy the catalytic converter, as the inefficiently combusted fuel produces soot (excess carbon) and unburned fuel in the exhaust flow can produce soot in the converter and drive the converter beyond its normal operating temperature range.
One way to mitigate the problem is to reduce the boost pressure, which reduces the required venting volume and yields less charge overcalculation by the ECU. The air can also be recirculated back into the intake, a typical stock setup for cars with an upstream MAF sensor. The situation can also be corrected by switching the fuel metering system over to a manifold absolute pressure sensor, a conversion that usually requires a compatible aftermarket ECU or piggy-back fuel controller. The MAP sensor monitors the absolute pressure in the manifold at all times and will correctly detect the change that occurs when the valve vents, allowing the ECU to reduce fuel metering accordingly.
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jai
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PostSubject: Re: Blowoff valve   Tue 03 Nov 2009, 00:39

Operation

A blow-off-valve is connected by a vacuum hose to the intake manifold after the throttle plate. When the throttle is closed, manifold vacuum without pressure develops in the intake manifold after the throttle plate and "sucks" the blow off valve open. The excess pressure from the turbocharger is vented into the atmosphere or recirculated into the intake upstream of the compressor inlet.
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jai
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PostSubject: Re: Blowoff valve   Tue 03 Nov 2009, 00:40


to the wastegate and bov.
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adam garage
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PostSubject: Re: Blowoff valve   Wed 18 Nov 2009, 00:35

wow..siap gambar..................................................
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jai
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PostSubject: Re: Blowoff valve   Wed 18 Nov 2009, 05:26

untuk lg senang paham bha..xbgitu?huhu
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arul
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PostSubject: Re: Blowoff valve   Tue 12 Jan 2010, 23:04

klu bahasa melayu lg paham hehehe....
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matnoor
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PostSubject: Re: Blowoff valve   Wed 13 Jan 2010, 01:02

nice nice nice..phm la jua skit..hehehe..klu x mau pakai pun bole..tp, pasti kan tebo yg di gunakan pada asal nya tdk pakai blowoff..mcm tebo diesel tdo4, starlet ct-9 kah..huhu ni ada otai ckp hari tu..aku copy dari mulut dan paste p sini..
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Emanrina
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PostSubject: Re: Blowoff valve   Wed 13 Jan 2010, 08:47

baik cerita tubo suda kamu...kekekeke...kansil ku nda lg mengechingggg bah...wakakakakaka

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matnoor
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PostSubject: Re: Blowoff valve   Wed 13 Jan 2010, 11:01

n/a pun best bah man..hehehe..kasi tggi ja compres bru lah mnginjat..
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Emanrina
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PostSubject: Re: Blowoff valve   Wed 13 Jan 2010, 12:20

850cc..wkakakaka...masuk piston 660...masuk adjustable & highcam..

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Sebarang pertanyaan mengenai kelab, garage, marchandise @ aktiviti dan yang berkaitan diatas sila hubungi terus ditalian Emanrina 013-5416225 @ King05 013-2410229
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matnoor
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PostSubject: Re: Blowoff valve   Wed 13 Jan 2010, 14:05

naaa ko kuasa itu..hehehe
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Emanrina
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PostSubject: Re: Blowoff valve   Wed 13 Jan 2010, 16:45

kuasa tggl diblakang la..abis kana pancit olih tubo...mataiii..wakakakakaka

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Sebarang pertanyaan mengenai kelab, garage, marchandise @ aktiviti dan yang berkaitan diatas sila hubungi terus ditalian Emanrina 013-5416225 @ King05 013-2410229
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jai
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PostSubject: Re: Blowoff valve   Thu 14 Jan 2010, 05:31

emanrina_kcar wrote:
850cc..wkakakaka...masuk piston 660...masuk adjustable & highcam..

kuat jua 2..huhu
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Emanrina
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PostSubject: Re: Blowoff valve   Thu 14 Jan 2010, 21:25

lidut sja bah tu jai...hehehe

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Sebarang pertanyaan mengenai kelab, garage, marchandise @ aktiviti dan yang berkaitan diatas sila hubungi terus ditalian Emanrina 013-5416225 @ King05 013-2410229
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PostSubject: Re: Blowoff valve   Today at 22:25

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Blowoff valve

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