With an article of this kind, it’s usually a good idea to start right from the basics, where we have a candid discussion of what a blow off valve is and exactly how it works. It will be much easier from there to talk about what to look for in a good blow off valve and which are the best blow off valves to buy in the market. That said, you will probably have any negative opinions of blow off valves changed after this article. Despite so many myths being perpetuated about blow off valves, these are actually pretty handy things to have. So, let’s start at the proper place: the beginning.
- Features to consider in Good Blow Off Valves
- Top 10 Best Blow Off Valves 2024
- 1. TurboSmart Kompact
- 2. GReddy Stiff Spring Blow Off Valve
- 3. GFB Diverter Valve
- 4. LGT TMS Respons Blow Off Valve Kit
- 5. Dewhel Universal 50mm V-Band Blow Off Valve
- 6. HKS Super SQV4 Sequential Blow Off Valve Kit
- 7. Boomba Racing Blow Off Valve
- 8. Go Fast Bits T9351 dv+ Blow Off Valve
- 9. GReddy Blow Off Valve
- 10. TurboSmart TS-0203-1061 Blow Off Valve
- Guide to Buying the Best Blow Off Valves
Features to consider in Good Blow Off Valves
What, exactly, is a Blow Off Valve?
You might not even know it as a blow off valve. These things go by a variety of names. You might know it as a dump, a recirc, which is really short for recirculate, a top off valve, a diverter, or a bypass. Of course, all of these terms are valid, and you should be able to recognize them if a friend or a particularly learned mechanic refers to your blow off valve as anything other than “blow off valve”. At the very list, you won’t look ignorant. That said, there is no one correct name for a blow off valve and the many that are used are all correct. They tend to change depending on the country and the region, even within the same country. However, they all do one job, and they do it pretty well.
A blow off valve has just one job, and that is to relieve excess pressure in the turbo. This pressure comes about as a result of shutting off the throttle rapidly whenever you’re boosting your engine. That said, you’ll already have figured something important out at this point, and that is that you don’t really need a blow off valve if you don’t have a turbo to begin with. The next time someone asks you if you can get a blow off valve, even if you don’t have a turbo, I bet you’ll feel pretty enlightened as you explain it to them. If you install a blow off valve in your car without a turbo, all you’re going to have is a pretty expensive, but regular, car.
So why do we really need a blow off valve? You might be wondering if the turbo pressure is even something we should be worrying about in the first place. The reason is that, if the pressure doesn’t find an easy release, then it will figure its own way out of the system. It’s fluid under high pressure, and high pressure should eventually be released. The only way that pressure will get out of your engine, sans a blow off valve, is by going back through your turbo and out. That is the last thing you want in your turbo because that way it won’t last very long. A lot of experts also argue that a blow off valve makes your turbocharger last a lot longer than it would without one. In fact, it might even protect your turbo from damage.
How does a Blow Off Valve work?
The majority of blow off valves operate in one of two ways: For most factory manufactured blow off valves and aftermarket blow off valves, the method is to use dual pressure signals that tell the blow off valve which valve to open. Most of the other types of blow valves will use only one pressure signal.
Dual Pressure Systems
In a dual pressure system, the system is arranged so the that the side of the valve prone to pressure is attached to a pipe lying between the throttle and the turbo. A vacuum hose will then connect the top of the valve with the inlet manifold that is fixed after the throttle body. The valve will naturally be held shut by a spring.
Whenever you engage the throttle, the pressure in the inlet manifold and the turbo piping is pretty much equal. The valve will remain shut because the pressure on either side cancels off. However, when you let go of the throttle you’ll have a lot more pressure coming from the turbo piping than the inlet manifold. In fact, there will be a vacuum in the inlet manifold. The pressure pushing against the bottom of the valve and the fact that there is absolutely nothing on the other side means the valve will be force lifted and opened in order to release the excess pressure in the turbo piping.
Some Myths about Blow Off Valves
1. The most common myth when it comes to blow off valves is that you have to tighten the spring on the valve if you want a higher boost. This isn’t necessarily true. The pressure is pretty much equal on both sides of the valve at full throttle, which means your boost pressure has no effect on the valve.
However, there are factory valves that have been designed in such a way that will crack open when you run a higher throttle. This is mostly to protect your engine from dangerous boost spikes. They achieve this by manipulating the pressure so that it isn’t equal on either side of the valve. That way, the spring will be overcome when the pressure gets to a certain point.
2. There’s a common fluttering sound that comes when you’re driving your car with a blow off valve attached. A lot of people think the fluttering sound is coming from the blow off valve. That’s not true, either. The truth is that the sound is caused by a blow off valve. However, it does not actually come from the blow off valve. It is more to do with the spring holding the valve shut. If the pre-load is too tight, the compressor will surge, which is the loud noise you hear as air comes out of the turbo.
Let’s have a closer look at compressor surge in order to understand it. The surge is pretty much the point where the blades begin to lose air, thereby compromising their ability to pump. It’s like how an aircraft stalls and loses some of its lift. In a turbocharger, this will occur in bursting sounds because the blades will alternate between slipping out air and biting. The resulting pulse is what causes the fluttering noise.
Compressor surge is much more common at low shaft speeds. When driving a road car, between 2000 RPM and 3000 RPM, you really won’t have to deal with compressor surge since the load generated by the surge tends to be very small when compared to the load generated at high boost. However, if you drive at high RPM and experience compressor surge, then you might end up damaging your Turbo.
With that small introduction, we should get into it and find out which are the best blow off valves to try out. Here are 10 of them.
Top 10 Best Blow Off Valves 2024
1. TurboSmart Kompact
Editor’s Rating:
Design and Performance
This blow off valve is a direct bolt-on replacement for the valve that comes from the factory for most EcoBoost, EFR, and BorgWarner turbos. As a result, it’s pretty much a good fit for most engines. It has almost instantaneous pressure response that’s probably only matched in speed by electricity. Additionally, it is housed in solid billet aluminum and has a small body that makes for very easy installation.
The kit comes with everything you’ll need for installation and doesn’t require much moving and removing of parts and hoses in your engine to fit the blow off valve. In terms of performance, it has a dual port construction that offers some of the best responsive flow characteristics on the market, thereby maximizing the sound output and pushing the air. Speaking of sound, it produces the most beautiful sound on this list. That’s why it got the highest rating.
Hear the beautiful sound here
Pros
- Small size
- Easy installation
- Excellent performance
- Beautiful sound
Cons
- No major cons
2. GReddy Stiff Spring Blow Off Valve
Editor’s Rating:
Design and Performance
The GReddy line of blow off valves is well known for its dedication to performance, and this blow off valve does not disappoint with its performance-oriented design. It is a universal fit that will go into most engines with a lightweight and an extremely small size. You will, however, love the beautiful sound it produces despite that small size, and so will onlookers on the road. It is also fully adjustable with a 47 mm valve.
The GReddy is functional. It’s designed to do its job and be very good at it, not stand out for everyone to see without delivering an iota of performance. That’s something a lot of blow off valves do: they become attention seekers rather than performers. This particular valve was designed to be better than that, going for optimal performance and a strong, durable build.
Separate article here
Pros
- Easy to install
- Solid build
- Beautiful sound
Cons
- Installation kit not complete
3. GFB Diverter Valve
Editor’s Rating:
Design and Performance
This simple valve has among the simplest installations you will find in the market at the moment. You can easily replace the parts that don’t work and still maintain the valve as a long-term solution.
The GFB uses a factory solenoid coil that allows for the most seamless integration you could ask for. The design is such that all the plastic valves have been replaced with metal valves, which makes for much greater durability and strength, allowing the valve to resist such things as chips.
The GFB diverter valve also uses the TMS system, which means it comes with the same advantages as the GFB Respons. The diverter valve can be replaced via direct fit and has a pilot actuated system that offers a much more rapid response than its competitors no matter what the level of the boost. This blow off valve pretty much solves the problem of a weak valve mechanism that is suffered by its peers by introducing a housing molded out of billet aluminum. The housing, in turn, is fitted with a well-machined brass piston so that it can tolerate a lot more stress.
With a product like this, the throttle response is a lot sharper and the valve actuation is a lot more rapid. This diverter valve also solves some of the problems experiences by old pneumatic valves that needed exceptionally long hose runs, OE wiring loom, ballast resistors, additional parts, different solenoid valves, and so much more, just to function properly. The end result was a slower response, longer installation times, and a much less powerful effect than what you get with this modern and efficient diverter valve.
To make things even better, this diverter valve is especially easy to install and improves your performance while making very few compromises. You will never have to deal with compressor surge or hear turbo flutter. Re-builds and replacement springs will also be a thing of the past. Couple that with a virtually unbeatable price and what you have, my friend, is a winner.
Separate article Walkthrough on YouTube
Pros
- Great solid build
- Affordable price
- Easy to install
- Can handle high boosts
- Eliminates compressor surge
Cons
- It isn’t universal
4. LGT TMS Respons Blow Off Valve Kit
Editor’s Rating:
Design and Performance
When it comes to price, the LGT TMS Respons Blow Off Valve Kit is right up there with the most expensive of them. However, despite the lofty price, this valve is very good and has some incredible features. For starters, you never have to worry about a compressor surge when you have this blow off kit. It also has just about every single component you could possibly need to install it. It has one of the most impressive performances on the market and not only improves the drivability of your vehicle but also protects your turbo system and improves its longevity. As if that’s not enough, the sound from this blow off valve is nothing if it isn’t mind-blowing.
The settings are fully adjustable, meaning you can easily tune it to perform just how you want it to. The performance can easily be fine-tuned to your expectations. The build is also exceptionally sturdy and will likely last you for many years of great performance.
The blow off valve itself is pretty dainty with small dimensions and is easy to locate in your engine. You don’t have to move any hoses or parts around to find a home for this little device in your engine. Even so, while it is so small and seemingly inconsequential, you can bet you’re going to get a lot of heads turning just to see where on earth that mind-blowing sound is coming from.
Separate article Walkthrough on YouTube
Pros
- Very easy to adjust and tune
- Has an incredible sound
- Looks very crisp and unique
- Offers great value for money
Cons
- A little on the pricier side
5. Dewhel Universal 50mm V-Band Blow Off Valve
Editor’s Rating:
Design and Performance
Dewhel Universal didn’t go wrong when they built this CNC machined blow off valve from 6661 aluminum alloy. The product features a V-Band design and has a 50 mm valve. The mounting is aluminum and the installation is pretty easy. Overall, the blow off valve looks clean and unique both before and after installation as it blends in seamlessly with the rest of your car. The O-ring on the valve seal is Viton and the coating is hard-anodized, The lubrication is Teflon and this blow off valve is one of the most wear resistant you will ever come across. You can expect it to last you a very long time, serving you faithfully before you have to retire it.
The Dewhel Universal 50 mm V-Band Blow off valve comes with a banjo-type bolt and air fitting, a first of its kind, and is machined with aluminum. The silicon on the actuator is resistant to high temperatures, boosting the durability of the device even more. The diaphragm inside is reinforced with Nomex, which means the components are very strong and will easily resist any backtracking by the boost. This blow off valve also comes in a wide variety of colors and offers up to 60% more in terms of airflow than other counterparts with a more traditional design. With flow like that, you’ll find it hard to get a blow off valve with more flow in the market.
Pros
- Great for all turbo upgrades, including intercooler
- Machined from 6061 aluminum alloy
- Has a high-quality short stroke diaphragm
- Can tolerate very high boost pressures due to the dual spring system
- Has a beautiful sound
Cons
- Needs an adapter for some engines
6. HKS Super SQV4 Sequential Blow Off Valve Kit
Editor’s Rating:
Design and Performance
This great blow off valve comes from the great engineers at HKS and is mid to high priced, depending on where you get it. The performance is pretty much out of this world as the valve opens and closes very quickly to exert excellent control over the excess boost coming from the turbocharger.
The design on this beauty is sequential and helps the HKS Super SQV4 Sequential Blow Off Valve Kit perform excellently against compressor surges. You really never have to worry about another compressor surge once you get this blow off valve. As if optimizing your performance isn’t enough, the clean sound produced by this blow off valve is just incredible.
This particular blow off valve is a little larger than what you would expect from the average blow off valve. It does, however, come with some really great features. There are 3 zip ties, C-clips, a vacuum filter, an O-ring, and “T” fittings. Pretty much everything you could ever require to fit this blow valve into your vehicle comes with the kit. There is also a small and handy booklet with detailed instructions for the installation process. You could practically do it yourself in an afternoon.
Because of how popular it is in the market, the HKS Super SQV4 Sequential Blow Off valve Kit happens to be pirated a lot. That means you’ll have to be extra careful when you’re buying one and should only make your purchases from the right vendors and should ensure your blow off valve is, in fact, manufactured by HKS.
Separate article Walkthrough on YouTube
Pros
- Has everything you need for installation in the box
- Has exceptional build quality
- Has a slick look and a great sound
- Is very easy to install and can be adjusted easily as well
Cons
- Is a little larger than normal
7. Boomba Racing Blow Off Valve
Editor’s Rating:
Design and Performance
This blow off valve is one of the more pragmatic ones on this, list, doing its job simply without too much fanfare. That said, the price is also pretty affordable and delivers good value for money. The only con with this valve is the fact that it lacks a good sound. It definitely is loud, but it won’t deliver that beautiful whoosh you will get from other valves on this list, hence the rating.
It features an internal brass piston housed in a solidly built aluminum body for maximum strength and durability and comes with all the mounting hardware you’ll need. It’s pretty light and small and is very easy to install, making it easy for you to locate it within your engine without a fuss. It will also easily withstand boost pressures of up to 70 pounds per square inch, making it a great aftermarket blow off valve.
Separate article Walkthrough on YouTube
Pros
- High performance
- Affordable
- Solid build
Cons
- Lackluster sound
8. Go Fast Bits T9351 dv+ Blow Off Valve
Editor’s Rating:
Design and Performance
This blow off valve is a good case of money well spent. It is extremely affordable compared to other blow off valves that perform at the same level. It also delivers beautiful quality performance. Just a warning, however, to save yourself some buyer’s remorse: make sure it is compatible with your car as it is not a universal fit.
The Go Fast Bits T9351 dv+ Blow Off Valve is very simple in its design. It can be installed very easily and quickly due to the retained factory solenoid coil. That means integrating it into your engine is an extremely easy task. It can also be fitted directly, which makes its assembly much simpler.
With other blow off valves on the market, you’re typically required to replace your entire turbo system to fit them. Now, we all know how complicated and costly that can get. It tends to affect the performance you get from your turbocharger as well; the response is much slower. With this blow off valve, you won’t experience any of those issues.
The system is pilot actuated and is an example of great technology. This technology is patented by the manufacturer and helps the blow off valve to deliver exceptional performance that is difficult to match by its competitors. The pilot actuated system helps to deliver very quick response times to your turbocharger, even when the boost is particularly high.
Separate article Walkthrough on YouTube
Pros
- Completely eliminates compressor surge
- High response rates due to pilot actuated system
- One of the most affordable blow off valves on the market
Cons
- Has a bit of a weak O-Ring
- Isn’t a universal fit
9. GReddy Blow Off Valve
Editor’s Rating:
Design and Performance
This blow off valve is one of a new generation of blow of valves that have the new floating valve design. It has been shown to be a lot more efficient than other valve designs. The GReddy Blow Off Valve has all the advantages of the models that came before it, such as the push valve structure and the silicone diaphragm control, as well as a whole new set of advantages, including a new and improved adjustable dual spring system that makes for very easy opening and closing and effectively prevents compressor surge. The design of this new model also features much better resistance, a better response, increased valve travel, and more airflow, all of which make a great contribution to the exceptional performance of the blow off valve.
The GReddy Blow Off valve weight just under one and a half pounds and has dimensions of 9 inches by 5 inches by 7 inches. It is much smaller than most blow off valves on the market but remarkably happens to be a lot more efficient and offers much better value for the price. You don’t have to move any engine parts or hoses when installing it, making for a very simple installation process. The installation kit contains an Allen gasket wrench and all the tubing you need, which means you don’t have to worry about any of those. The only thing you’ll have to worry about is the flange, which you will have to purchase separately. The sound is also one of the best on the market.
Pros
- It is compatible with all blow off valve flanges from GReddy
- It is highly durable
- It produces a loud and high-quality sound
- It has a universal floating valve design and fits in most engines without the need for an adaptor
Cons
- The installation kit does not contain a flange
10. TurboSmart TS-0203-1061 Blow Off Valve
Editor’s Rating:
Design and Performance
Sometimes all you want is a blow off valve that gives you most of the performance features of the expensive models but comes at a reasonable price. You love blow off valves, but you don’t want to have to break the bank to afford one. In that case, you can hardly do better than the TurboSmart TS 0203 1061 Blow Off Valve. This blow off valve is a favorite for many consumers due to its crisp look and feel and the whoosh sound it makes when you let your foot off the gas pedal. The design is quite unique and is made to amplify the sound coming from the blow off. The build is also quite solid and strong and guarantees great sound and long-lasting performance.
The dimensions on this blow off valve are 7 inches by 6 inches by 5 inches, which makes for a blow off valve that is quite easy to handle and install. You don’t have to move stuff around in your engine and can easily find a spot to place it. The valve is also pretty lightweight at 7 ounces, even though it comes with a very solid build. You might be feeling a little apprehensive with such a small thing in your engine, thinking it’s not the head-turning variety. However, with the impressive sound it produces, it’s definitely guaranteed to turn a lot of heads. It will also improve the turbo response in your engine when you shift gears and prevent compressor surge due to its efficiency.
Separate article Walkthrough on YouTube
Pros
- Very easy to install
- Produces an excellent sound
- Has adjustable hard and soft settings
- Does not have any boost leaks or idle issues
Cons
- It isn’t universal
Guide to Buying the Best Blow Off Valves
As mentioned earlier, a blow off valve is pretty important to the proper functioning of a turbo system. It also has many names, including pop off valve, bypass, dump, recirc, and so on. The names are different in different countries and regions. However, they all refer to the same thing that performs the same job all round.
The main objective of a blow off valve is to make your drive much smoother if you’re installed a turbocharger in your car. It’s also there to protect your turbo from serious damage and to increase its longevity. This valve is what causes the very loud sound you hear in turbocharged engines. Of course, some people love that sound and will install a blow off valve in their cars, just to hear the loud noise coming from their engine, much to the chagrin of other motorists. Others, however, are more concerned about performance and install blow off valves in their vehicles for the same reason.
All the same, having a turbo system means you have a responsibility to find the right blow off valve for your turbo system. If you do, then you can look forward to a healthy and happy engine. Here we’re going to tell you how to do that.
A Note on Compressor Surge
Your turbo system consists of a lot of different components that have to work in synchronicity in order to create the power your vehicle needs to get a boost in speed. These parts work like a perfect orchestra, for the most part. However, there is a little chaos that can slip in every now and then in the form of a compressor surge. A compressor surge can cause serious damage to your turbocharger if left unchecked. Your car’s performance will definitely be affected and parts of your engine may be susceptible to significant damage. But before we get so grim, let’s learn a little more about what a compressor surge is than we did at the beginning of this article.
A compressor surge is caused by the closing of the throttle plate when you suddenly release the gas pedal. There is a rush of boost to the engine, but it pretty much comes up against a solid wall when it hits the throttle plate. That boost, enthusiastic as it is, now is trapped and has nowhere to go. Okay, maybe it does have a place to go: back from whence it came, to the turbocharger. This is actually pretty common and is known as ‘boost backtracking’. The boost makes its way back to the turbocharger and gets into the compressor outlet. There it becomes quite a nuisance as it interferes with the proper operation of the compressor wheel. This is what we call the ‘compressor surge’ and it can cause some serious damage as it could potentially stall the shaft and wheel bearing. The result will be more stress than necessary on the turbocharger and engine components.
This isn’t just about damaging your engine, though that certainly is something to worry about; it’s also about the drivability of your vehicle being compromised because the turbo’s response is all messed up. You wheel will begin to lose momentum and get a terrible lag. Your car engine will perform sub-optimally and your acceleration will be in the doldrums. That’s part of the reason why a blow off valve is so important. It protects your turbo system against such problems. It prevents the compressor surge by venting the excess boost right out of the system and into the air. That’s where that loud and polarizing sound comes from.
The Basics of a Blow Off Valve
A blow off valve is connected to the intake manifold of the turbocharger. It has a vacuum chamber with a valve in one of its main houses, a diaphragm, and a spring. When the throttle is open or closed, the diaphragm engages instantly due to the change in pressure. This is the dual valve operation we talked about at the beginning of the article. At a certain vacuum (in some factory valves), the diaphragm will pull away in the direction of the vacuum source. This will cause the spring to get compressed in its house. The spring is connected to a valve that releases the excess pressure to the atmosphere.
If you want your blow off valve to perform optimally, you should adjust it so that the pressure at which the valve in the intake system is activated is controlled. Most cars with a turbo system will have a dynamometer for this very reason. The dynamometer will take measurements of the horsepower output and the torque. The readings will determine how much you have to adjust your blow off valve to achieve the activation pressure that you want. It’s important, however, that you pick the right blow off valve for your particular engine so you can avoid most of this.
What is a Recirculation Valve or Diverter?
It’s important to point out that you won’t find a blow off valve in all engines with a turbocharger. In fact, some turbochargers have a different category of blow off valve entirely, which uses a different mechanism to control boost and compressor surge. A good example of this is the MAF-type system, which requires a recirc valve, also known as a diverter.
Such a system will meter the airflow as it gets into the intake system. When this happens, a bunch of complications occurs, including rich AFR, bad idle, stalling, and hesitant acceleration. That’s where the recirc valve comes in. it takes the excess pressure and redirects it into the turbocharger, instead of releasing it into the atmosphere.
The Sound from a Blow Off Valve
When a blow off valve either releases boost into the atmosphere or redirects it into the turbocharger, it will produce any one of a wide variety of distinct, adrenaline-raising, and sometimes appealing hissing noises. Depending on how the exit of the boost has been designed, you can install different kinds of blow off valves to amplify or clarify the sound. The blow off valves shaped like a trumpet, for instance, produce a very loud hissing noise. Some car owners even buy blow off valves for the sole reason that they like the noise they make.
What Qualities do the best Blow Off Valves have?
- Easy installation: The very best blow off valves will have a straightforward installation process based on either an adaptor specific to a particular vehicle, a pipe mount, or a horse mount. Whichever method used, it’s a great idea to go for the blow off valves that come with their own “bolt-on” kit. They won’t require much of your effort and can be installed in no time.
- They can easily be adjusted: If you’re going for a specific performance level or sound, then you’re going to have to adjust your blow off valve. The turbo system you’re using will be a great determinant in the diameter of blow off valve you choose to purchase and install. Always go for a blow off valve that can easily be adjusted to boost the turbo response every time you shift gears. It should also easily eliminate compressor surge and prevent the boost from leaking out of the system prematurely.
- They are well built: The best blow off valves in the market have an incredibly strong build. With a component that works so hard, you want a build that promotes durability, longevity, and reliability. You should never purchase any blow off valve that has been entirely made from plastic. That won’t last very long and will be a complete waste of your money. Instead, go for blow off valves that have been molded out of durable cast metal and bullet aluminum frames. The piston should also be anodized aluminum. Products with stiff metal die-cast are also a great option.
- They produce a good Sound: Just as mentioned before, the sound of a blow valve is important in determining the purchasing decisions of many drivers. The sound is considered aesthetic and some sounds will appeal to you more than others. The very best blow off valves will produce an aggressive and dynamic sound. However, this may change depending on which design you go for. What you should really be looking for is good quality sound. You also shouldn’t go for any blow off valve that makes a rattling sound.
Ultimately, choosing the right blow off valve guarantees that you not only have a smooth driving experience and protect your turbocharger and engine, but you also enjoy an aesthetic sound coming from your engine and wow onlookers as you speed by. Choose the right one and you will never drive the same.
