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A blowoff valve is a pressure release system present in turbocharged engines, its purpose is to prevent compressor surge and reduce wear on the engine. Turbocharger Cut-away A turbocharger is a device used in internal-combustion engines to increase the power output of the engine by increasing the mass of oxygen and fuel entering the engine. ...
A compressor stall is a situation of abnormal airflow through the compressor stage of a jet engine, causing a stall of the vanes of the compressor rotor. ...
Definitions
A compressor bypass valve (CBV) also known as a compressor relief valve is a vacuum-actuated valve designed to release pressure in the intake system of a turbocharged or centrifugally supercharged 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 mass airflow sensor (MAF) determines the mass of air flowing through a conduit. ...
A blowoff valve, (BOV, sometimes hooter valve, dump valve) does basically the same thing, but releases the air to the atmosphere. This creates a very distinctive sound desired by many who own turbocharged sports cars. Some blowoff valves are sold with trumpet shaped exits that amplify the "boooooom" sound, these designs are normally marketed towards the tuner crowd. For some owners this is the only reason to get a BOV. Motor sports governed by the FIA have made it illegal to vent unmuffled blowoff valves to the atmosphere. In the United States, Australia and Europe cars featuring unmuffled blowoff valves are illegal for street use. The trumpet is a musical instrument in the brass family. ...
For the British rock band of the same name, see Amplifier (band). ...
Disadvantages The unique sound caused by a blowoff valve (but not a compressor bypass valve) sometimes comes at a price. On a car where the blowoff valve is mounted after the mass airflow sensor, venting to atmosphere confuses the engine control unit (ECU) of the car. The ECU is told it has a specific amount of air in the intake system, and injects fuel accordingly. The amount of air released by the blowoff valve is not taken into consideration and the engine runs rich for a period of time. Engines with a manifold absolute pressure regulated ECU or where the blowoff is mounted upstream of the MAF sensor are not affected. A mass airflow sensor (MAF) determines the mass of air flowing through a conduit. ...
An Engine Control Unit (ECU) is an electronic control unit which controls various aspects of an internal combustion engines operation. ...
The manifold absolute pressure (MAP) sensor is an important sensor in modern internal combustion engines that use fuel injection. ...
Typically this isn't a major issue, but sometimes it can lead to hesitation or stalling of the engine when the throttle is closed. This situation worsens with higher boost pressures. Eventually this can foul spark plugs and destroy the catalytic converter (when running rich, not all the fuel is burned which can heat up on and melt the converter or leave heavy carbon deposits). This article or section should include material from Spark gap A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed aerosol gasoline by means of an electric spark. ...
Catalytic converter on a Dodge Ram Van. ...
Purpose Blowoff valves are used to prevent compressor surge. Compressor surge is a phenomenon that occurs when lifting off the throttle of a turbocharged car (with a non-existent or faulty bypass valve). When the throttle plate on a turbocharged engine running boost closes, high pressure in the intake system has nowhere to go. It is forced to travel back to the turbocharger in the form of a pressure wave. This results in the wheel rapidly decreasing speed and stalling. The driver will notice a fluttering air sound.
Operation
throttle open, blowoff valve closed
throttle closed, blowoff valve open A blow-off-valve is connected by a vacuum hose to the intake manifold after the throttle plate. When the throttle is closed, underpressure develops in the intake manifold after the throttle plate and "sucks" the blowoff valve open. The excess pressure from the turbocharger is vented into the atmosphere or recirculated into the intake upstream of the compressor inlet. derek likes it in the ass Image File history File links Size of this preview: 732 × 599 pixelsFull resolution (816 × 668 pixel, file size: 33 KB, MIME type: image/jpeg) I MADE THIS PICTURE IN MICROSOFT PAINT!!!!! I, the copyright holder of this work, hereby release it into the public domain. ...
Image File history File links Size of this preview: 732 × 599 pixelsFull resolution (816 × 668 pixel, file size: 33 KB, MIME type: image/jpeg) I MADE THIS PICTURE IN MICROSOFT PAINT!!!!! I, the copyright holder of this work, hereby release it into the public domain. ...
Image File history File links No higher resolution available. ...
Image File history File links No higher resolution available. ...
In automotive engineering, an intake manifold or inlet manifold is a part of an engine that supplies the fuel/air mixture to the cylinders. ...
Manifold vacuum, or engine vacuum in an internal combustion engine is the difference in air pressure between the engines intake manifold and Earths atmosphere. ...
See also Dump valves are fitted to the engines of (usually older) turbo charged cars and sit between the turbo outlet and the throttle body. ...
A wastegate is a valve that diverts exhaust gases away from the turbine wheel in a turbocharged engine system. ...
References - Allard, Alan. Turbocharging and Supercharging. Cambridge, England: Patrick Stevens Limited, 1982.
- Gorla, Rama, and Khan, Aijaz. Turbomachinery Design and Theory. New York, New York: Marcel Dekker, 2003.
- Society of Automotive Engineers. Turbochargers and Turbocharged Engines. Warrendale, PA, 1979.
- Watson, N, and Janota, N. Turbocharging the Internal Combustion Engine. London, England: Macmillian Press Ltd, 1982.
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