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Turbocharging provides added theatrics to an engine in more ways than just more power. There’s the soundtrack that comes along with it, and sadly, many turbochargers cars lack a powerful and just plain neat sound when shifting. Who wants a barely audible hiss when you could have something that sounds like a rally car, or a TCR race car? That can be changed with a blow-off valve (BOV), which vents boost pressure under deceleration—so it’s quite necessary and functional—yet also sounds cool.
When it comes to functionality, too much compressed air may build up in the engine’s intake system. This causes high pressure that leads to a compression surge in the engine, which manifests as an unpleasant sound. A blow-off valve safely releases this excess air. Then, installing a BOV is typically the next step after you install a turbocharger. It helps the entire turbo system function more efficiently and makes the drive much smoother.
This buying guide will help you find the best blow-off valve to keep your turbocharged engine operating efficiently, and also provide some straight-up cool additions to your vehicle’s soundtrack.
Summary List
- Best Overall: Turbosmart TS-0203-1023 Blow-Off Valve
- Best Value: Go Fast Bits T9103 Diverter Valve
- Best High-End: HKS Racing SQV Universal BOV – 71008-AK004
- Honorable Mention: GReddy Blow Off-Valve
Our Methodology
To come up with this list, we utilized both our general knowledge of turbocharging and the performance aftermarket. There are many blow-off valve options out there, but we decided to stick to options from five of the most trusted brands. Do your research when it comes to proper fitment and setup, but each of these should fulfill their purpose well, which is to vent and/or recirculate boost pressure efficiently and effectively.
Technology changes, though, so we might update it from time to time with the most pertinent information. Or, introduce better options. For more on how we select products, read this.
Best Blow Off Valves: Reviews & Recommendations
Best Overall: Turbosmart TS-0203-1023 Blow-Off Valve
Pros
- Quality overall construction
- Good price
- Trusted name
Cons
- Could develop leaks over time, especially when dealing with high boost
This Turbosmart BOV has a solid build and an innovative design that’s lighter than most BOVs on the market. It also has a sleek body with a space-efficient design to make it easier to install. The performance is outstanding despite its size, and it will produce a sublime whooshing sound once you take your foot off the throttle. It’s designed with an O-ring sealed piston and can handle a boost pressure of up to 30 psi.
It only takes a few minutes to install since it goes in with very little hardware. Also, we are impressed that it’s reasonably priced for a product with a solid design that produces great amplified sound.
Naturally, it’s not a perfect product since there have been a few complaints that its performance may diminish over time—it may get too loud and start to rattle. You should also inspect it from time to time for leaks.
Best Value: Go Fast Bits T9103 Diverter Valve
Pros
- Quality product
- Nice construction
- More stealth than the other options
Cons
- Would require some modification to fit on any non-late-model Subaru
If you are looking to improve overall reliable performance, yet not make too much noise, then installing the T9103 is a great place to start. It’s a recirculating unit: For instance, if you use it on a Subaru WRX, then it will recirculate the air back into the system.
The system lets you regulate how much air you can vent or recirculate to control the quality of sound. There are some helpful videos online that will help you install and learn how to regulate it. However, if you allow it to vent entirely, it can cause the engine to backfire. The price is also one of its most significant drawbacks seeing that there are cheaper options that come with mounting kits.
Best High-End: HKS Racing SQV Universal BOV – 71008-AK004
Pros
- Strong construction
- All the included hardware
- Classic sound
- Large size accomodates similarly large turbo setups
Cons
- None to report
HKS offers a high-performance BOV that’s a bit on the large side but doesn’t cut corners with its performance. It’s constructed with an aluminum die-cast body that’s designed to tolerate excess pressure from the turbocharger. It doesn’t disappoint when it comes to the authentic whooshing sound that we love with BOVs.
What’s more, it’s a universal fit, and installing this BOV will be a breeze thanks to the extra tools that come with the kit: an O-ring, T-fittings, a C-clip, a vacuum filter, and a complete guide that provides the steps for installing the fittings.
You should note that you may have to purchase a separate flange for a seamless installation and a plug for the recirculating hose. Also, it might cause a compressor surge, but this shouldn’t be a big issue if installed and used correctly.
Honorable Mention: GReddy Blow Off-Valve
Pros
- Easy universal fitment
- Good response while shifting gears
- Accomodates different recirculation adapters
- Heavy duty internal diaphragm
Cons
- Finish might wear off over time
- Expensive
This GReddy BOV is a versatile valve that fits almost any type of vehicle on the market. This is because of its universal floating valve design that doesn’t need a mounting adaptor. It’s a great upgrade from the previous GReddy BOVs since it uses the same mounting holes. In addition, a heavy-duty silicone diaphragm controller is fitted inside the unit to help improve the response time when shifting gears. It also makes the valve more long-lasting.
What’s special about this BOV is that it has a CNC outlet with discharge ports that draw more air from the surrounding area to enhance the blow off sound without the need for extra air pressure from the engine. The CNC outlet is customizable and you can replace it with recirculation adaptors of different sizes.
However, this BOV has a few disadvantages. For one, it’s expensive. Also, it’s exterior build construction doesn’t last as long in comparison to other models.
Our Verdict on the Best Blow-Off Valves
We chose the Turbosmart TS-0203-1023 Blow-Off Valve as our top pick for the best BOV unit since it’s solidly built for the price. It also adds a nice sound enhancement to your turbocharger and is quite easy to install.
If you are looking for a more inexpensive unit, consider the Go Fast Bits T9103 Diverter Valve.
Features to Know About Blow Off Valves
Here’s what you should consider.
Types of Blow Off Valve
Vented: Vented BOVs release air into the atmosphere and are the easiest to install. Most have a trumpet at the exit vent to amplify the hissing sound as the air releases. However, traditional BOVs release all the pressure into the atmosphere, and if you are using a manual transmission, you may experience turbocharger lag when shifting gears.
Hybrid: An adjustable, also known as a hybrid, BOV solves the problem that vented BOVs have by venting some of the air into the atmosphere and recirculating the rest back into the intake system. As a result, the boost pressure no longer needs to start from zero since some of the pressure is retained. This helps reduce lag when you’re shifting gears. You should only use this type of BOV if you have a mass airflow sensor in your engine.
Features
Compatibility: There are some universal-fit BOVs available on the market, but it’s prudent to do your homework to make sure the option is compatible with your car. To avoid getting the wrong size, always prioritize models that are advertised to be a custom fit for your vehicle’s year, make, and model.
Ease of Installation: You can’t go wrong by choosing a product that comes with a mounting kit and installation instructions. You will find it easier to install versus buying a stand-alone product and the mounting hardware separately.
CBV vs BOV: Whether or not you install a BOV depends on how your engine deals with the excess air pressure. Some engines need a compressor bypass valve (CBV) that directs pressurized air back into the non-pressurized intake for better engine performance. Consult with your owner’s manual or a professional on the type of valve to use.
FAQs
You’ve got questions. The Drive has answers.
Not if it’s installed correctly on the turbocharger. In contrast, it will maintain the best operating air pressure in your engine to prolong its life. It will also minimize surge loading and help maintain turbine speeds in between shifts. It should mount between the throttle plate and the turbocharger compressor.
Between $100 and $500 is a safe bet.
Both units work to regulate the pressure of exhaust gases but in different ways. The turbocharger discharges pressure from the turbo when you release the throttle. A wastegate regulates the level of boost from the turbo by redistributing the excess pressure from the boost to the turbine wheels with the help of an actuator spring.
