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On gasoline engines, blow off valves are plumbed between the turbocharger compressor outlet and the throttle body. They prevent potential damage to the turbocharger...
On gasoline engines, blow off valves are plumbed between the turbocharger compressor outlet and the throttle body. They prevent potential damage to the turbocharger due to a phenomenon known as compressor surge. When the engine transitions from boost to closed throttle, pressure can build up between the turbo and throttle plate. This surge can rapidly slow the compressor wheel, resulting in accelerated wear and possible damage to the turbocharger. It also causes turbo lag when the throttle is re-opened and the driver has to wait for the turbocharger to spool up before it can begin making boost again.
The main components...
On gasoline engines, blow off valves are plumbed between the turbocharger compressor outlet and the throttle body. They prevent potential damage to the turbocharger due to a phenomenon known as compressor surge. When the engine transitions from boost to closed throttle, pressure can build up between the turbo and throttle plate. This surge can rapidly slow the compressor wheel, resulting in accelerated wear and possible damage to the turbocharger. It also causes turbo lag when the throttle is re-opened and the driver has to wait for the turbocharger to spool up before it can begin making boost again.
The main components of a BOV, sometimes called a dump valve, are a housing, spring, and piston. The upper portion of the valve references intake manifold pressure via a hose. At idle, the blow off valve is held shut by spring pressure. Under boost, both spring pressure and manifold pressure continue to hold the valve closed. When the throttle is closed, manifold vacuum helps lift the piston against spring pressure, allowing boost to escape to atmosphere. In some applications, blow off valves recirculate boost pressure back to the inlet side of the compressor; these are often referred to as diverter or recirc valves. With many blow off valves, additional springs are included to adjust the opening to a desired amount of manifold vacuum. Depending on the vehicle or engine management used, blow off valves can also be electronically controlled, with no vacuum line to the intake manifold.
In applications with a centrifugal supercharger, a blow off valve performs the same function, allowing pressure to escape when the throttle is closed but the compressor is still creating boost. It can also function as a supercharger wastegate, limiting maximum boost.
While they are traditionally used on turbocharged gas engines, blow off valves are also used on high-performance diesel engines to vent excess boost pressure under deceleration, when the engine is slowing rapidly.
Blow off valves are often classified by size in millimeters, with 50mm being common size. Universal blow off valves often mount with a V-band clamp, and a weld-on fitting may be included for installation. They can also mount with a hose barb, 3-bolt flange, or OE-style mounting for factory replacement units. Shop a huge selection of blow off valves from Summit Racing, Turbosmart, TurboXS, Precision Turbo & Engine, Vortech, and more.
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Go Fast Bits VTAs are a performance blow-off valve solution for a wide range of foreign and domestic cars and trucks with an electronic factory diverter valve. If you want sound with your performance (or performance with your sound!), these VTAs offer just that! By combining the proven performance benefits of GFB's ground-breaking DV+ with atmosphere venting, the VTA delivers an aggressive blow-off sound, improved throttle response and boost recovery, as well as superior boost holding and reliability in extreme conditions. The VTA shares the successful DV+ design philosophy: "Keep what works, replace what doesn't." This means Go Fast Bits retained ECU control and the solenoid from the factory diverter to ensure the fastest possible response time—without the added and unnecessary cost of replacing the solenoid like some brands do. The weak part of the factory diverter has always been the plastic valve mechanism; this is the part GFB has replaced. The VTA features CNC-machined billet components that last a lifetime, and the valve operation method has been updated for better performance. The factory diverter valve can only operate in two states: open or closed. When it opens fully at low boost or during a partial throttle lift mid-corner, it causes increased lag and a noticeably non-linear boost transition. GFB pioneered the use of "pilot operation" in the DV+, which works by re-purposing the factory solenoid to control the pressure behind the piston rather than the piston itself. This allows the solenoid stroke to be much shorter, speeding up the response time and increasing the actuation force. More importantly, it allows the piston to open and close progressively in response to the amount of boost pressure present, which smooths boost transitions and reduces the lag caused by the factory diverter valve. It's this design philosophy that makes the VTA not only the best performing blow-off valve solution, but also the best value on the market. Order the VTA Performance blow-off valve model recommended for your vehicle. Key features: * TMS Technology for faster boost recovery on gear shift and during throttle modulation * Improved boost holding ability * Atmosphere venting for blow-off sound * Retains ECU control * Simple, direct bolt-on kits include everything you need to install
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