Written By Car Bibles Staff
Published Jul. 22, 2019

When a turbo charged car is in town, boy do you know it thanks to that familiar and powerful popping sound. The source of the crackle is its blow off valve, and if your turbo beauty doesn’t have one then it needs one pronto.

Also known as a diverter or pop-off valve, the blow off is actually more than just a loud noise. This mechanical powerhouse will also protect your car’s engine, boost its performance, smooth out the drive, and ultimately keep those repair bills down.

To help you get the best out of your turbo-charged motor we checked out the best blow off valves hitting the mechanic’s car pit, so you can continue to drive your wheels loud and proud.

The Best Blow Off Valve

The DV+ is a direct fit blow off valve that has an impressive build quality for its mid-end price. With minimal plastic parts, Go Fit Bits has boosted the valve’s mechanism by replacing the housing with an anodized billet aluminum shell and a brass piston that is engineered to exact tolerances. The result is a turbo blow off valve that is slick to fit and gives you a sharper throttle response and as much boost as you can pitch at it without any turbo flutter. Once in place, everything just feels smoother and your car performs as if it’s just had a professional tune up. The DV+ is a great value and good quality for its price tag.

Key Features
  • Direct fit replacement for the factory diverter valve
  • Retains factory solenoid coil for seamless integration
  • ‘Pilot-actuated’ valve mechanism for rapid response
  • Plastic valve parts replaced with metal
Specification
  • Brand GFB
  • Model T9351
  • Weight 7.2 ounces
PROS

One of the most affordable quality blow off valves around

Smooth operator with an even smoother sound

Eliminates compressor surge

CONS

Not a universal fit so make sure it is compatible with your car model

This mid-priced turbo blow off valve totally nips those compressor surges in the bud, giving you performance and a power boost that will put a smile on your face.  And although this unit is larger than the usual blow off valve, the sound it produces is sublime as is the control it gives over the excess boost of your turbocharger. The installation features of the Super SQV4 are nifty too with C-clips, an O-ring, T fittings and a vacuum filter that make fitting as well as using this loud blow off valve a pleasure. The installation guide is also easy to use. In short, quality engineering from the HKS team has resulted in a high-performing blow off valve at a good price.

Key Features
  • Aluminum die-cast body
  • Triple gin design to produce sound
  • Pull-type relief valve operation
  • Full installation kit included
Specification
  • Brand HKS
  • Model 71008-AK001
  • Weight 1.54 pounds
PROS

Well-thought out installation kit makes the Super SQV4 easy to fit

Quality engineering that is clear to see…and hear

CONS

On the larger side for a blow off valve

If loud and proud is your thing, then check out this solidly built blow off valve from Turbosmart.  There is something deeply satisfying in taking your foot off the throttle to release its distinctive whoosh, but this smart unit is more than just about turning heads.

The Turbosmart comes in at a mid-price point, and you get a lot of quality for your money. Its clever shape is designed to amplify sound as well as ensure long-lasting performance. Coming in at a manageable size, it is also pretty lightweight compared to others on the market, but this is in no way a lightweight blow off valve. It will improve the efficiency of your turbo engine nicely; the response underfoot is awesome, and it works well to prevent any compressor surge. Now that is something to shout out loud about.

Key Features
  • Easy to handle and install size
  • Lightweight design
  • O-Ring sealed piston
  • 30PSI boost handling capability
Specification
  • Brand Turbosmart
  • Model TS-0203-1061
  • Weight 7 ounces
PROS

Produces a head-turning smooth sound

Quick and easy to install

CONS

Not a universal fit so check compatibility with your car

Here’s a blow off valve that doesn’t really like to make a fuss. If you prefer a valve that gets on with its job then the Boomba for the Ford 2.0L EcoBoost OEM Turbo is certainly worth a look. It does make a sound – and a pretty loud one at that – but it is not quite on par with the more vocal blow off big boys. Its sound is a little lacking when it comes to that lovely whoosh that sets your turbo apart. But with its lack of ‘voice’ you do, however, get a good unit that is easy to install, and it can stand up to boost pressures of up to 70 pounds per square inch. Plus, it is made from aircraft-grade billet aluminum, so it promises a quality build that is both neat and durable.

Key Features
  • Made from aircraft grade billet aluminium
  • Pressure tested to up to 70psi
  • Mounting hardware is included
  • Available in four colors
Specification
  • Brand Boomba Racing
  • Model 022-00-006R
  • Weight 5 pounds
PROS

Impressive performance for its price

Quality, durable build

CONS

Only compatible with the Ford 2.0L EcoBoost OEM Turbo

Sound is missing the blow off whoosh we all love

Machined from CNC aluminum alloy and featuring a large 50mm valve, the Dewhel is our best value pick due to its price as well as its universal use.

You get a lot of nice engineering tech, including a banjo-type air fitting and bolt that is machined from aluminum and comes complete with an 10mm hose barb for a fast response. There is also a high-temp silicone Nomex-reinforced diaphragm for a longer shelf life. This really is an impressive turbo blow off valve and one that is durable and easy to fit. It comes complete with all the fittings. When put to the test, the sound is stunning and is certainly not budget priced.

Key Features
  • 50 mm V-Band Blow off valve
  • Banjo-type bolt and air fitting
  • Nomex-reinforced diaphragm
  •  Available in a wide range of colors
Specification
  • Brand Dewhel
  • Model BOV-50MM BLACK
  • Weight 1.7 pounds
PROS

A build and performance quality that is beyond its price-tag

Takes high boost pressures all in its blow off stride

CONS

You may need an adapter to fit your car’s engine – check with the dealer

As one of the ‘new generation’ blow off valves that come with a floating valve design, the efficiency of the Greddy is top notch. The floating valve has an updated adjustable dual-spring system. The upgraded design makes the spring preload setting less dependent on the idle, giving a much better response and more air flow. And there are also discharge ports that draw in air to amplify its growly blow off sound.

The overall design of the blow off valve housing is slimmer, making the Greddy smaller than many other turbo blow off valves currently on the market. But its boosted efficiency makes it a great value.  Complete with its own installation kit, the beauty of the small but perfectly formed Greddy is that you won’t need to move any engine parts when installing it, so getting this loud blow off valve up and running is a breeze.

Key Features
  • Floating valve design
  • Discharge ports to draw in air
  • Slimmer design to the valve housing
  • Comes complete with an installation pack
Specification
  • Brand Greddy
  • Model 11501665
  • Weight 1.39 pounds
PROS

Floating valve design fits in most engines without the need for an adaptor

CONS

Near the top end of our best blow off valve review

A direct bolt-on replacement for the factory valve, this is an excellent fit for Mazdas. It gives an immediate pressure response when you ask for it. Small with a neat design and engineered from solid billet aluminum, the Turbosmart Kompact easily gives you the performance you need without the super loud noise. This is very much a blow off valve that likes the performance to speak for itself. The sound itself is sweet, yet not head turning loud, making the Turbosmart Kompact a blow off class act.

The valve comes complete with everything you need to install the unit, and fitting the valve is not too challenging. This is a quality blow off valve with a sweet sound you will be pumped to take out around town.

Key Features
  • Made from solid billet aluminum
  • Full recirculating blow off valve
  • Small body for easy installing
  • Comes with installation kit
Specification
  • Brand Turbosmart
  • Model TS-0203-1209
  • Weight 1.1 pounds
PROS

Produces a stunning, classy sound

Small but perfectly formed, with impressive performance

CONS

Nothing major to report

Sometimes simple is best, and when it comes to the Go Fast Bits DV Diverter the title pretty much fits. Easy to fit, easy to maintain, and a decently priced unit, we think the DV diverter is a great option. It fits seamlessly to the factory solenoid coil, and all the valves are metal, boosting its strength and durability. The whole housing is also machined out of billet aluminum. There is a pilot actuated system for a rapid response regardless of the boost level, and there is no compression surge. You will also notice the smooth transition when accelerating and less turbo lag. To top it off, you get a turbo blow off valve that is super neat and easy to install. It’s definitely worth the investment as this is one blow off valve that will be with you for some time.

Key Features
  • Seamless integration with the factory solenoid coil
  • ‘Pilot-actuated’ valve mechanism for rapid response
  • Machined out of billet aluminum
  • Quick and easy to install
Specification
  • Brand GFB
  • Model T9356
  • Weight 6.4 ounces
PROS

Easily handles high boosts and nicely eliminates compressor surge

CONS

Not universal so check it is compatible with your car

This is a premium pick, but you get your money’s worth, especially if you want to create some awesome sounds. You also get a complete installation kit – including a 5mm wrench – so you can be sure of a smooth and hassle-free fit.

But for the price, how does it perform? It’s impressive. It is direct vent, so you need to get the dialing right, but when you do you will feel it. The smooth transmissions and quick response times give you an awesome ride with no turbo flutter or compressor surge. The valve also has fully adjustable settings, so you can fine tune the performance to where you want to be. Yes, it is pricey, but the build quality is superb and has certainly been designed to last. And its relatively compact size makes it easy to install. This is one of the best sounding loud blow off valves hitting the road, and you won’t be disappointed if you are happy to pay the premium price.

Key Features
  • Compact 8x4x8 inch size
  • Full adjustable settings for sound
  • Up to 30% faster boost recovery on gearshift
  • Holds unlimited boost pressure
Specification
  • Brand GFB
  • Model T9001
  • Weight 1.15 pounds
PROS

One of the best sounds you can get from a blow off valve

Come with a complete installation kit

CONS

It is right at the top end of our best blow off review budget

For a blow off valve that ticks all the key boxes without sending your credit card into melt down, we think the Turbosmart Kompact is a pretty good bet.  This is a full recirculating turbo blow off valve that gives you a decent amount of performance and sound without going too over the top. It is also a well-made unit at a reasonable price. You won’t get that’ hey, look at me’ total sound blast, but it will still deliver the whoosh you are looking for.

The dimensions of the Kompact live up to its name, but the smaller size makes it easier to install without much moving around in your engine. The build is solid too, despite its size, and you will certainly feel the difference in your engine’s performance. The turbo response is greatly improved as you shift gears, and it nicely eliminates all that unwanted compressor surge.

Key Features
  • Full recirculating blow off valve
  • OEM type fitment
  • For Mazda and Subaru
  • Green spring rated -15 InHg
Specification
  • Brand Turbosmart
  • Model TS-0203-1209
  • Weight 15.2 ounces
PROS

Nice, low-key blow off sound if subtle is the way you like to go

Smaller size makes it easy to install

CONS

Not universal – for selected Mazda and Subaru models

Best Blow Off Valve Buying Guide & FAQ

Things to Consider When Buying Blow Off Valves

Always get advice from your mechanic or local garage if you are unsure about adding a blow off valve to your turbocharger. Other things you need to consider when selecting the best blow off valve for your BOV car include:

  • Build quality

that blow off valve is going to be put through its turbo paces so always check the build quality of the model you are looking to buy. You want a valve that is durable, reliable and will have a long lifespan so always avoid a model that is made entirely from plastic. Turbo blow off valves molded out of cast metal with a bullet aluminum frame and a piston made from anodized aluminum are a good way to go.

  • Compatibility

always do your research and make sure the blow off valve is compatible with your car as one size does not fit all. 40mm is the most used diameter for a blow off valve but your car may need a different size.

  • Sound and noise rating

you want to get a good sound out of your loud blow out valve as a pay-off for all your efforts and some sounds are more appealing than others. You are looking for a cool, dynamic and yup, aggressive sound that has a clean quality to it, rather than a rattling sound. Also check the noise rating on the valve as while you want to turn those heads, you don’t want to receive a noise abatement order after the neighborhood complains.

  • Ease of installation

go for the most straightforward installation system as blow off valves should be totally user-friendly. Be clear on the mounting method of your chosen blow off valve and check that it comes with its own bolt on kit, so you can crack out the instructions and crack on with the installation in no time.

  • Adjustability

if a specific performance level or turbo blow off valve sound is important, then opt for a model that can be easily adjusted. Ease of adjustment also means a more effective turbo response when you shift the gears and help to accurately eliminate that compression surge.

  • Maintenance

look for a blow off valve that is easy to maintain as it be prone to wear and tear with prolonged use. One weakness in turbo blow off valves can be a tendency to eventually leak so check the build quality and materials used – and opt for one with a warranty if you can.

  • Cost

when adding a blow off valve to your precious turbo-wheels, we recommend you go for the best you can afford. Valves with a cheap price-tag can prove costly in the long run as they could damage your engine or under-perform. See a blow off valve as an investment rather than a short cut.

Related Posts: Best Shock Absorbers, Engine Flushes and Fuel Stabilizers

Benefits of Installing A Blow Off Valve

If you have installed a turbocharger on to your car, then a turbo blow off valve is an important piece of extra kit as it supports the effective functioning of the whole turbo system. The main benefit of installing a blow off valve is to make the drive in your turbocharged car much smoother and to protect the turbo from wear and damage. It is also there to prevent compression surge, which creates an unpleasant sound from the engine caused by high-pressure air that is trapped in the intake system.

The overall outcome is an improved performance and a turbocharger that will have an extended ‘shelf life’ and the need for less servicing and repair. The added bonus (to some!) is the loud popping sound that will turn heads and hopefully impress as you drive by.

Types of Blow Off Valves

When it comes to choosing the right type of blow off valve for your turbo-charged car, your life is made easier as there are only two main types on the market:

Vented blow off valve – with this valve the air is released into the atmosphere, making installation easier than its alternative.

Recirculated blow off valve – as the name indicates, this type of blow off valve recirculates the air back into the system. This type of blow off valve is the one to choose if you have a mass air flow sensor in your engine.

Best Blow Off Valve FAQ:

Q: What is a blow off valve?

A blow off valve can be added to a turbocharged car to not only improve performance but to protect and extend the life of the turbo charger. Mounted in the intake plumbing between the turbocharger compressor and the throttle plate, a blow off valve works by blowing off the pressure in the intake system. This way, the valve works to prevent surge loading, helping to extend the life of the turbocharger and prevent costly repair bills. And, while this may seem to many to be the primary reason for many to add a blow off valve, it can also be tuned to create a hissing or whooshing sound every time you change gear. And if the pimped-up look of your turbocharged ride doesn’t turn heads, that loud blow off valve crackle certainly will.

Q: How does a blow off valve work?

What does a blow off valve do? Well, here’s the turbo geek bit: attached to the intake system, the blow off valve has a vacuum chamber which contains a spring, diaphragm and valve. The diaphragm responds to any pressure changes and at the set level (which on many models you can manually adjust) the diaphragm is pulled towards the source, compressing the spring inside the valve housing. The spring is attached to a valve which is then pulled away to release the unwanted boost pressure. Job done…and you get a throaty blow off crackle as a reward!

Q: Do superchargers need a blow off valves?

Blow off valves are only meant for turbochargers so if you’re thinking of getting one for your supercharger, then don’t as it will be a waste of money. A true supercharger works with forced induction and is designed to stay on and recognize pressure, so doesn’t need a blow off valve to sense a pressure build up and vent it off. However, some superchargers are centrifugal rather than using a combustion system and so a form of blow off valve can be used – but it will also need a mass-air meter installed otherwise a blow off valve will be pointless and can actually lead to performance issues in your car.

Q: Can a blow off valve damage your engine?

If fitted correctly and to a turbocharger (and not a true supercharger) then no, it will not damage your car’s engine.  In fact, as it is designed to reduce surge loading and maintain turbine speeds in between shifts, the best blow off valve actually helps to protect and extend the life of both the engine and the turbocharger.

Our Top Pick

For price, build quality and usability, the Go Fast Bits DV+ Blow off Valve comes out as out review’s Top Pick. A solid design, within minimal plastic and top engineered mechanisms, the DV+ gives a smooth ride and an even smoother sound. Add in a sharper throttle response, and no turbo surge and you have a bow off valve that will have your car performing like a super-slick operator.

Source:

  1. Does your car need a blow off valve? – The Motorhood

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