HKS is a popular brand among car tuners and enthusiasts for quality aftermarket performance parts. They began manufacturing a revolutionary pull-type of blow-off valve in 1994 and has since been favored by owners looking for stellar performance and that much sought after “hiss” sound. For some it’s about sound, for others it’s about efficiency. Whatever the reason, HKS blow off valves serve both desires.
The HKS BOV utilizes the built up vacuum pressure created when the throttle is closed to pull open the valve and release the pressure immediately, whereas a push type reacts slower, as it utilizes a spring that pushes the valve closed until a certain pressure is achieved. A pull type BOV actuates faster and allows faster spool up of the turbo.
In traditional push type BOV’s, the spring typically must be tightened until it matches the pressure needed for the assembly to vent, depending on the type of engine you have. The HKS BOV is completely plug-and-play and doesn’t have to be adjusted once installed.
The elimination of surge is primary selling point for the HKS BOV’s. In short, their design eliminates the surge by efficiently and quickly venting off the pressure with no leakage. When the pressure builds up in the air system, it surges back up into the turbo, causing the blades to slow down and travel in the opposite direction, referred to as “backspin.” This repeated slowing and backspin strains the turbo, shortens its life and causes damage to the engine.
Some drivers want that “whoosh” sound which the HKS provides beautifully, with no sputtering or fluttering sound (that’s the surge you hear) between gear shifts. While the purpose of the BOV is to prevent surge to the turbo, the audible sound the venting of the excess pressure gives your car that “wow-factor” of a highly-tuned performance vehicle.