The blow off valve is also called a safety valve, which can be automatically opened and closed according to the working pressure of the system, another feature is that it bring a smooth hissing sound when you are decelerating, in a way this sound has become a symbol of a modified car.
How Blow Off Valve works
When you step on the pedal of a car equipped with a turbocharger to accelerate, the throttle valve will automatically open, and the engine will make a sound. The engine discharges the high temperature and high pressure exhaust gas, which promotes the rotation of the exhaust gas turbine. When the speed of the turbocharger exceeds 100,000 rpm, the turbocharger spins the surrounding air. The air is effectively compressed, thereby increasing the intake air volume of the engine and improving the power performance of the engine. When it stops, due to inertia, the turbo will still continue to spin for a certain amount of rotation at more than 100,000 rpm. At this time, the air is still continuously compressed into the intake pipe. If this part of the high-pressure air in the intake pipe cannot be discharged in time, the pressure in the intake pipe will rise rapidly, resulting in acceleration delay. , The acceleration is not smooth, and it may cause damage to the throttle valve or burst of the intake pipe. In fact, the blow off valve is installed on the intake pipe to control the boost pressure. Once the pressure exceeds the critical value, it will energize or de-energize the solenoid coil to open or close the relief valve.
The Benefits of Blow Off Valve
1.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.
2.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.
3.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.
How to choose a good blow off valve
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.
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.
4.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.
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.