Blow Off Valve Buyer's Guide

A blow off valve (BOV) is what gives a turbo car the whoosh noise that you love. It is a device that allows high-pressure air to be let off into the atmosphere when you let off the gas. A BOV is indispensable for cars with turbos as they make the turbos last longer. When the system is pressurized, and you let off the gas. air tries to go back though the turbo. It forces the turbo to back spin, thus damaging it. For this reason, BOVs are installed.

How It Works

When a car is running at high RPMs, a huge amount of air continuously enters the engine through the throttle. What the turbo does is compress it. As long as the throttle is open, the air moves along. However, when you lift your foot off the pedal to slow down, the compressed air is stuck. Here, the BOVs start functioning. They let off this compressed high-pressure air into the atmosphere, thus preventing damage to the turbo. This action produces a variety of sounds, which car enthusiasts generally love. Interestingly, some valves are made such that they enhance the sound. For example, some are fitted with trumpets-shaped outlets to give a better sound. Racing cars offer many great examples.

HKS Super Sequential Blowoff Valve (SSQV)

HKS designed the first Sequential Blow-Off Valve in 1994. This pull-type valve was engineered in such a way that it was stable no matter how much boost or pressure is present. Its unique pull-type sequential valve structure was an auto lover’s delight. Now, the latest Super SQV 3 has a nickel-plated, die-cast metal secondary valve, and a stainless steel C-Clip and spring. To prevent duplication, the blow off valve has a holographic HKS logo on its back; in addition to logos on it body. This valve is stable, and it doesn’t leak with high pressure, nor is it ever under vacuum. This is how the SSQV works. It has two valves: primary and secondary. The primary valve opens initially for light pressure, followed by the secondary valve under high pressure conditions. The HKS SSQV can be used for custom applications as well. Along with its functions, this valve has a powerful blow-off sound and appealing appearance.

Subaru Impreza WRX/STI

If you have a Subaru Impreza WRX/STI, it is necessary to know that it has unique blow off valve requirements. APS designed ones specifically for this model. With this twin-vent valve, the turbo response is better and improved. Moreover, it increases the durability of the turbocharger. This APS valve has a 30 micron hard anodized, T6 billet aluminium body, low friction bronze piston and all stainless steel hardware.

BOVs really enhance the performance of your vehicle. Make sure you have the best one for your car, based on design and output. A dual drive blow-off valve is ideal for fast cars, as they respond to all kinds of pressure situations. One thing to keep in mind is to get a valve that has a urethane gasket as it ensures a tight seal.