Tokyo Express

HKS compressor blowoff and bypass valves play a vital role in any turbo system because they not only improve the performance of your vehicle but they also increase the longevity of the turbocharger as well.

The primary function of any blow-off or by-pass valve is to prevent compressor surge by relieving the compressed airflow that reverses direction as the throttle is closed. HKS blowoff and bypass valves reroute the pressurized air that is normally forced backwards into the turbo compressor into the intake stream or by venting it to the atmosphere. Subsequently, engine performance is then increased from quicker turbo spool up, as the compressor speed is not reduced by the backward airflow.

The longevity of the turbo is also increased, as its bearings will not suffer from the impact that is also produced by compressor surge. Though many vehicles incorporate factory by-pass valves, they are often undersized and quickly are beyond their capable operating range as airflow levels are increased. HKS offers four types of compressor blowoff and bypass valves: Standard, Racing, Super Sequential Blow-Off Valve, and the Racing Blow-Off Valve Type II.

HKS SSQV Blow Off Valve - Mazda - Nissan - Subaru - EVO - Toyota - VW

The HKS Super Sequential Blow-Off Valve (SSQV) is a dual stage pull-type relief valve. Unlike typical push type blow-off valves, the SSQV will not leak under any level of boost because the boost pressure in chamber "C" keeps the valve closed against its seat (Diagram 1). The SSQV releases excess boost when there is a pressure alteration in chambers "A & B", not by the rate of boost pressure or vacuum in the line.

This ensures a quick valve response and complete closure during idle. Many competitors use a push-type
blow-off valve design with a large valve to accommodate high boost / high horsepower applications. These large valves react slowly and require high pressure to open, and are not able to activate and prevent compressor surge at light-load conditions.

On the other hand, smaller, fast reacting push-type valves do not discharge the airflow capacity required for high horsepower applications and tend to slowly open and leak as boost pressure overpowers the spring. For maximum performance, the HKS SSQV incorporates
both a small primary valve for ultra quick activation, and a larger secondary valve for additional discharge capacity. The SSQV is engineered to initially open the small primary valve at light throttle and load conditions
(Diagram 2), then sequentially opens the secondary valve for additional relief capacity under high boost and load conditions (Diagram 3).

The SSQV is constructed of polished billet aluminium, which ensures long-term durability and a high lustre look. The mounting base utilizes a circular mounting flange that combines with a C-clip snap ring and O-ring gasket to insure an excellent seal. The triple-fin discharge port design produces a powerful, unique and aggressive blow-off sound.

The HKS SSQV is available in vehicle specific kits or as a universal unit for custom applications. Vehicle specific HKS SSQV kits come complete with all mounting flanges, brackets, and miscellaneous hardware for an easy
installation. For Universal SSQV applications, weld-on flanges are available
in steel or aluminium for custom installation.

HKS SSQV Insert

The HKS SSQV silver triple-fin discharge design produces a powerful and unique aggressive blow-off sound along with added visual distinction. Additional triple-fin inserts are available in gold (standard high frequency
sound) for visual appeal and in purple metallic (emits a lower frequency sound than both the standard and gold SSBV inserts) for an alternate sound and appearance. SSQV inserts are easily interchangeable within minutes.

HKS Racing Blow Off Valve Type II

The HKS Racing Blow Off Valve Type II is a pull-type blow off valve for high horsepower applications. Similar in construction and function to the HKS SSQV, the Racing Blow Off Valve Type II uses a large single stage, aluminium pull-type valve to handle the extreme pressure and airflow discharge volume that is associated with high boost / horsepower applications. The Type II is
engineered to accommodate up to 3.0 bar (43.44psi) of boost and can function accurately on vehicles in the 800 horsepower range. The Racing Blow Off Valve Type II utilizes the same circular mounting flange and billet
aluminium construction as the SSQV to provide outstanding flow and a perfect seal.

HKS Standard and Racing Bypass valves are push-type valves that utilize calibrated spring rate and vacuum line pressure to remain closed against the pressurized air in the charge pipe. As the throttle plate closes, vacuum is
created in the line and combined with the force of the pressurized air in the charge pipe, the blow off valve pushes open and allows pressurized air
to escape.

HKS Bypass Valves

HKS Racing Bypass Valves function like the Standard Bypass Valves, but incorporate an additional pressurized port to insure valve closure under extreme high boost levels. The Racing Bypass Valves can also be used as a
safety "pop-off" valve if the second port is connected to a pressure source that does not see vacuum. For added flexibility and function, HKS Racing Bypass Valves are offered in various adjustable boost pressure ranges that
are determined by a specific spring rate.