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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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Summit Racing™ 50MM blow-off valves are a pressure release system that takes the load off your turbocharger when the throttle is suddenly closed, preventing damage to both the turbo and your engine. These valves are adjustable from 0 to 50 psi, making them ideal for most boosted applications. Machined from aluminum and black anodized for durability, these blow-off valves offer a quality look for any turbo setup. They include vacuum fittings, aluminum weld flange, V-band assembly, and springs.
( 16 )
$69.99
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$245.99
Turbosmart Gen-V Race Port blow-off valves are small, lightweight, high performance components for forced-induction competition level engines. Featuring unique collar designs and internal flow structures, they are 46 to 50 percent lighter and 25 percent smaller than the competition, while flowing 330 cfm, making Turbosmart Gen-V Race Port blow-off valves the highest flowing BOVs of their type on the market. They are offered in several different anodized colors and versions to fit your race application. All are supplied with vacuum fittings, V-band assemblies, and installed springs. Additional features: * Billet 6000 Series aluminum construction * Quick-release V-band collar for ease of installation and removal * MIL-Spec hard-anodized valve guide and stem * High-temperature silicone Nomex® diaphragm * Twin 1/8 in. NPT pressure ports for convenient positioning * 2.0 in. inlet flows over 330 cfm * Collar secured cap for quick spring changes * Most Race Ports have blue spring rated -18 to -14 InHg installed * Female flange version available to suit other manufacturer's 50mm flanges (no weld-on fitting supplied) and is 46 percent lighter * HE (Hall Effect) sensor cap versions allow you to monitor blow-off valve position for diagnostic or tuning purposes * Supercharger-specific versions have a soft pink spring rated -4 InHg installed, so it can stay open at idle, when supercharger is still producing boost
( 2 )
$324.95
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$534.95
Turbosmart Vee Port blow-off valves are an ideal choice if you're looking for high flow, small size, and value! These BOVs feature a unique, variable exhaust port system, providing for the superior venting of excess pressure. Turbosmart Vee Port blow-off valves are the simple, yet effective solution for your application.
( 6 )
$382.95
VS Racing X50 blow-off valves are designed for use on large-capacity turbocharger systems and high-horsepower engines. Featuring a 50mm design, small size, and lightweight construction, VS Racing X50 port blow-off valves provide greater performance through faster turbo spool-up from idle, along with reduced turbo lag between gears. VS Racing X50 port BOVs are ideal for circuit and drag vehicles and trucks—so order today!
( 12 )
$78.00
If you are looking for a top-quality racing bypass valve, look no further than these Maxflow valves from Vortech. Key features include: * 320 cfm flow at 8 psi * Gasket for installation * Compact design is ideal for import applications and tight engine compartments * 2-bolt mounting pattern will retrofit to standard HKS/Greddy-style mounting pads
( 14 )
$394.99
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$423.99
Turbosmart Kompact EM dual port blow-off valves vent to the atmosphere and back into the air intake. These EM (Electro-Mechanical) BOVs are true plug-and-play upgrade replacements featuring a leak-proof design, lightning fast actuation, and higher pressure handling capabilities, making them high performance substitutes for your factory plastic units. They also allow you to retain complete OE control of their operation. Turbosmart Kompact EM dual port blow-off valves are all-billet CNC construction with high temperature seals and the latest patented technology. They are must-haves for hybrid or larger flowing turbos that utilize OE electronic diverter valves. By not leaking, the EM will achieve target boost without stressing the turbocharger and wastegate. Key features include: * Patent pending integrated pressure control * True plug-and-play upgrade * Integrated proprietary high-temperature solenoid valve * Billet construction with high-temperature O-rings
( 3 )
$303.95
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$576.95
Turbosmart Kompact dual port blow-off valves offer high performance, OEM fitment, versatility, and affordability—in other words, everything you need! These BOVs feature dual ports that vent into both the atmosphere and the air intake, reducing turbo lag and eliminating cavitation. Turbosmart Kompact dual port blow-off valves are designed to be bolt-on replacements for plastic factory Bosch or Denso units. They use sequential timing to allow for quieter operation during normal driving, while still providing the benefits of a vent-to-atmosphere type BOV under race conditions. They are easily converted into full atmospheric or full bypass units by using the included port blanking plug.
( 28 )
$207.95
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$571.95
Precision Turbo and Engine PTE blow-off valves are good for your turbo. They offer several styles to meet your performance needs. All are meticulously crafted from billet aluminum and finished with a durable black anodize for high-quality looks and performance. Styles and features of Precision Turbo and Engine blow-off valves: * PTE 30mm and 50mm BOVs are lightweight and compact in size, making them perfect for a vast majority of turbocharged applications. Adjustments are seamless without the need to remove the entire assembly from your vehicle. * PTE 64mm BOVs are extremely innovative without sacrificing durability or performance, while providing the highest flow available and tremendous tuning ability. Designed to release back-up pressure created when the throttle is closed via a spring-loaded valve diaphragm assembly, they are key components for preventing potentially harmful compressor surge backed into the turbocharger to reduce wear on both turbo and engine. Packaged with weld-on aluminum mounting flange, spring adjustment screw, and two top ports for ultimate versatility and adjustability.
( 1 )
$313.59
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$649.59
Turbosmart Kompact plumb back blow-off valves replace your factory BOV with higher performance! These bolt-on replacements offer a smart choice in OEM fitment and value. Kompact blow-off valves are built tough from black anodized aluminum, providing superior flow and greater structural integrity under boost. Turbosmart flange-type plumb back blow-off valves are available in a range of styles to fit many models—especially those with constrained engine bay access. They're full recirculating, directing all excess pressure back into your intake system. Swap out your factory plastic units for reliability, quality, and value with these Turbosmart Kompact plumb back blow-off valves.
( 8 )
$155.95
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$466.95
The Power Port is Turbosmart's largest and highest flowing blow-off valve ever, resetting the flow benchmark set by their popular and highly regarded Race Port blow-off valves. They are designed to be as light as possible, to keep vehicle weight down. The Power Port BOVs have a cutting-edge dual-chamber design, meaning they can be held open with the use of a solenoid to aid turbo response and control, during staging to give the best possible launch.
Not Yet Reviewed
$519.95
Turbosmart Vee-Port PRO blow-off valves are designed for today's modified turbo cars. Their small body is perfect for limited-space applications, while their unique, variable exhaust port system still allows for the efficient venting of excess pressure. Their hard anodized body and pistons are built to last and look good, even in the toughest conditions. They are available in either a blue or black finish with a clear anodized base to further complement your engine bay. To ensure years of service, Turbosmart offers a full line of replacement parts, so you can rebuild or modify these blow-off valves as you go. It doesn't matter if you are building a bad street car or a full-out race car--Turbosmart Vee-Port PRO blow-off valves will be perfect when size matters.
( 2 )
$225.95
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$240.95
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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$198.00
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$269.10
The Hybrid valve is back! Go Fast Bits Hybrid dual outlet valves are three valves in one; full recirculation, full atmosphere, or 50/50 venting. In 1999, GFB's first Hybrid valve pioneered the dual port design, which was so successful, and the technology has since been adopted by most other brands. By "staging" the two venting outlets at low valve lifts most of the air is recirculated. As the car is driven harder, the valve opens further and more of the atmosphere venting port is exposed for a louder sound--a benefit that makes it possible to use these valves on cars with sensitive airflow meters that often suffer issues such as backfiring and/or stalling, whilst still achieving the signature blow-off sound. Go Fast Bits Hybrid dual outlet valves are direct-fit, bolt-ons with a range that covers a huge list of popular vehicles. Purchase the Hybrid model for your vehicle.
( 2 )
$225.00
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$436.50
Big Bubba Sleeper blow-off valves from Turbosmart have been designed for big horsepower, high performance, and high-boost turbo, as well as supercharger applications! They're constructed out of heavy-duty CNC billet aluminum with a hard anodized aluminum 2-piece piston. All Big Bubba Sleeper valves use the same inlet flange and V-Band clamp as the Turbosmart Race Port to make things easier. With their -4 AN threaded vacuum port, you're capable of having a variety of connection methods. Big Bubba Sleeper Valves from Turbosmart are big, bold, and in-your-face, all in one lightweight package!
Not Yet Reviewed
$435.95
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$461.95
Superior flow performance and supersonic sound are yours with Turbosmart's Supersonic blow-off valves! Suitable for all turbocharged vehicles, these full atmospheric BOVs are designed for racers and serious enthusiasts who want to be noticed. They feature tool-free adjustment via a rotating cap and a positive-seal piston. Supersonic blow-off valves are the loudest BOVs in Turbosmart's lineup.
( 2 )
$246.95
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$372.95
Vortech Engineering standard bypass valves are specifically designed for street applications. They help eliminate compressor surge and reduce heat soak in the discharge tube. These units are recommended for vehicles running 6 to 12 psig. Both the inlet and outlet mate to a 1 in. hose.
( 4 )
$112.99
Granatelli Motor Sports' 50mm blow-off valves feature a 50mm design, compact size, and lightweight construction. These pressure release systems are designed to take the load off your turbocharger when the throttle is suddenly closed to help reduce the risk of damage to both the turbo and your engine. These BOVs are adjustable, making them ideal for many boosted applications. These 50mm blow-off valves are machined from top-grade aluminum and black anodized for added durability, and include the vacuum fittings, aluminum weld flange, the spring, and V-band assembly.
( 1 )
$74.81
Turbosmart Kompact EM series blow-off valves are a direct replacement for the factory, electronic diverter valve, created to provide a solution for improved response, boost holding and reliability. These award-winning Kompact EM Plum Back blow-off valves are the world's first truly plug-and-play blow-off valves. Simply unplug and unbolt the OEM blow-off valve and install the Kompact EM blow-off valve unit for your make and model in its place—no adapters, hoses or extra assembly is required. Additional features and benefits: * Billet aluminum construction with Hi-Temp O-rings * Patented integrated pressure control * Integrated proprietary Hi-Temp solenoid valve * Retains complete OE control of the BOV's operation * Plum back vents entirely back into the air intake * Complete unit replacement * True plug-and-play installation
( 2 )
$267.95
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$519.95
Go Fast Bits Respons TMS direct-fit blow-off valves with TMS Advantage allows you to infinitely vary how much air is recirculated or vented to atmosphere. Simply by twisting the adjustment ring, you can change the sound of your BOV from silent to ear-shattering! GFB's patented venting bias adjustment system can be tweaked between full recirculation (silent) and full atmosphere (loud). With the Turbo Management System (TMS) technology, Respons BOVs can return the engine to peak boost up to 30 percent faster than a factory diverter valve when shifting gears, offers better throttle response, and unlimited boost-holding. If cars like yours typically suffer issues such as backfiring and stalling when using a fixed-ratio atmosphere-venting BOV, the Respons valves can help. By adjusting the venting bias to suit the car you can achieve a blow-off sound without having to put up with the issues.
( 1 )
$307.80
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$585.00
Turbosmart Kompact recirculation blow-off valves feature a plumb back system that recirculates all excess pressure back into the intake system. They offer more versatility, OEM fitment, better structural integrity than a stock BOV, and superior airflow for better performance. These Turbosmart Kompact recirculation blow-off valves are the perfect way for enthusiasts to gain all of the benefits of a quality BOV without drawing unwanted attention.
( 5 )
$195.95
From the innovative minds at Turbosmart, the Dual Port Type 5 blow-off valves take your boost to the next level. Due to the unique design, the Dual Port Type 5 can be configured in four different configurations, making it Turbosmart's most versatile blow-off valve. Constructed from billet aluminum and available in several colors, these tough, reliable, and accurate blow-off valves will keep your system in check. Available in direct-fit, model-specific configurations or universal v-band mounting, there is a Dual Port Type 5 blow-off valve for you.
( 1 )
$393.95
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$765.95
If you want to enjoy your turbo but don't want to attract unwanted attention, Turbosmart plumb back blow-off valves are for you! These full recirculating BOVs redirect all excess pressure back into your intake system, providing you with quiet, street-legal performance!
( 1 )
$324.95
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$377.95
Go Fast Bits Respons TMS Universal blow-off valves with TMS Advantage are patented adjustable venting bias system diverter valves. GFB's Respons BOVs allow you to precisely control how much air expels from each of the two outlets, which is key for two reasons. First, you can adjust how loud the blow-off sound is--recirculate all of the air for silent factory operation, vent it all to atmosphere for maximum noise, or set it anywhere in between to suit your preference. Second, you get a blow-off sound without causing stalling, backfiring, or any other BOV-related issues, even on a car with a sensitive airflow meter (MAF). And this is accomplished by simply twisting the adjusting ring. GFB's Respons TMS Universal blow-off valves are not just noisemakers. They also offer better throttle response, faster boost recovery on gearshift, and unlimited boost-holding. Using GFB's TMS (Turbo Management System) principle, tests show that Respons valves can return the engine to peak boost up to 30 percent faster than a factory diverter valve when shifting gears.
Not Yet Reviewed
$307.80
Go Fast Bits SV52 blow-off valves are more compact and offer more flow. Standing only 86mm tall including the weld-on adapter, the SV52s have an astonishing boost pressure rating of 300 psi, and feature a monobloc body design, CNC-machined from a single aluminum billet that ensures strength without adding unnecessary bulk. They are designed with an anodized piston bore that creates an extremely hard and low-friction surface on which the single-piece aluminum 52.5mm piston glides and will continue to do so over countless cycles. The piston also provides strength and reliability, something a diaphragm cannot match in a high-boost BOV environment. Go Fast Bits SV52 blow-off valves include two springs, plus a spring pre-load adjustment system, so you can dial it in for optimum throttle response and boost recovery after gearshift, without resorting to the costly hit-and-miss approach of purchasing extra springs.
Not Yet Reviewed
$283.50
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