Best Blow Off Valves: Get More Sound From Your Engine
Use any of these blow-off valves to produce great turbo sounds
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BY Norah Tarichia / LAST UPDATED ON October 13, 2019
Many turbocharged cars lack a powerful sound when shifting. That can be changed with a blow-off valve (BOV) that takes the load off the turbo when you are decelerating to create a smooth hissing sound. Our buying guide will help you find the best blow-off valve to keep your turbocharged engine operating at its optimal level.
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Benefits of a Blow Off Valve
- Release high pressure from the engine. At times, too much 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 the excess air pressure.
- Compliment the function of the turbocharger. 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.
- Make your ride sound impressive. You can install a BOV solely for the impressive sound it produces. Some BOVs have an exit vent that’s shaped like a trumpet so that the air under intense pressure can make a louder sound as it leaves the engine. It can produce a loud whoosh or hissing sound, which can be satisfying and will turn heads as you drive.
Types of Blow Off Valves
Vented BOVs release air into the atmosphere and are the easiest to install. Most are designed with a trumpet at the exit vent to amplify the hissing sound as the air is released. 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.
An adjustable or hybrid BOV is designed to solve the problem 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.
HKS has been making some of the best sounding BOVs and aftermarket parts since 1973. Its main goal is to design products that make vehicles perform better than the manufacturers thought they could. If you want to sample one of its best BOVs, consider the HKS (71008-AK001) Blow Off Valve Kit.
GFB stands for Go Fast Bits. It’s an Australian company that designs a variety of high-quality blow off valves, pulley kits, boost controllers, and short shifters made from high-grade materials. Its products are designed to fit perfectly and to push the limits of high-performance engines. Some of its best-selling BOVs include the GFB DV+ Blow Off Valve.
Nic Cooper founded Turbosmart in 1997 in a small workshop in Sydney, Australia. Throughout the years, it expanded its roots from the local scene to global markets in the United States and Europe. Currently, it designs and sells blow off valves, wastegates, anti-lag valves, boost controllers, and a plethora of spare merchandise in over 50 countries globally. If you want to try out one of its hybrid BOVs, check out the Turbosmart Kompact Blow Off Valve.
GReddy is a sub-brand of Trust Company Ltd., which is a Japanese manufacturer of aftermarket car tuning parts. It’s a privately-owned company that was founded by Masamitsu Hayakawa in 1977. GReddy makes blow off valves, exhaust systems, cooling systems, and turbo kits. One of its best-rated blow off valves is the GReddy Blow Off Valve.
Blow Off Valve Pricing
- Under $100: You can get some of the best-sounding BOVs within this price range, but the sound is not a reflection of its performance. While most of the cheaper versions can fit a variety of car models, they are usually not designed to handle too much air pressure.
- $100 to $200: This mid-range price level consists of vented and hybrid blow off valves. Most of the vented versions can produce a high-pitched whoosh sound, while the hybrid versions may not be as loud but can fit a wider range of vehicles.
- $200 and up: Most of these BOVs are heavy-duty and are able to cope with a higher pressure. Installing most of the higher-priced options will go fairly smoothly so long as you have a direct fit for your vehicle's year, make, and model.
The construction or build quality of the BOV speaks volumes as to how long it’s going to last and the expected performance. The best ones are made from a billet aluminum frame with an internal piston made from anodized aluminum. Avoid anything that’s made entirely from plastic since it can melt or crack under intense pressure.
It’s important to consider the type or quality of sound you prefer. Do you like a soft hissing sound, or do you prefer a more aggressive sound that draws attention to your ride? Whatever you choose, ensure that it’s within the recommended noise rating to avoid getting noise complaints.
- 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.
Best Blow Off Valve Reviews & Recommendations 2020
- Observe a six-month cleaning interval for your BOV to remove dirt and other power-robbing contaminants. A dirty BOV sounds bad and can damage the turbocharger with time.
- Since you have to remove the BOV when cleaning it, you may want to take a picture before removing the unit to ensure that you return everything to the right place. Also, be careful not to crack or damage the brittle fittings when loosening the bolts.
- Remember to inspect the BOV unit for any signs of corrosion, scarring, and wear. Lubricate the metal parts with a non-viscous lubricant, and you can use pressurized air to clean out the BOV before reassembling it.
Q: Can a blow-off valve damage the turbo?
A: 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 be fitted between the throttle plate and the turbocharger compressor.
Q: Can I install a blow-off valve in a supercharged car?
A: Blow off valves can cause performance issues in supercharged cars. They are only designed for turbochargers. A supercharger is fitted with a forced induction instead, which is designed to recognize pressure build-up and vent it off. That’s similar to what a blow-off valve does for a turbocharger.
Q: What’s the difference between a blow-off valve and a wastegate?
A: Both units work to regulate the pressure of exhaust gases but in different ways. The turbocharger helps discharge pressure from the turbo when the throttle is suddenly released. A wastegate regulates the level of a boost from the turbo by redistributing the excess pressure from the boost to the turbine wheels with the help of an actuator spring.
We chose the Turbosmart Blow Off Valve as our top pick for the best BOV unit since it’s solidly built to outperform its competitors. It also adds a nice sound enhancement to your turbocharger and is quite easy to install.
If you are looking for a more affordable BOV unit, consider the ECCPP Turbo Blow Off Valve.