Turbo Cars: Blow off Valves
Blow-Off
Valves are one of the best investments you could make for your turbocharged
car. The blow-off valve (or by-pass valve) originates in the turbo era of Formula
One. It was found that when the throttle was released between gear changes (throttle plate closed), the pressure created by the turbocharger remained in the system and as a result pressurised the turbo into slowing down.
When the throttle is re-opened there is a momentary period of turbo lag, until it can spool up to speed again. The blow-off valve helps by releasing the excess pressure between the turbo and throttle plate, either into the atmosphere (externally venting) or back into the system (internally venting). With a good quality BOV fitted, lag between gear changes is gone and power can be available straight away.
GFB
Blow-off valves. GFB make a huge range of blow-off valves to suit any
turbo car. The range starts off with the GFB Basic, which is anodised and precision
machined for great looks and performance. If you require more volume, then the
Mach 1 and Bovus Maximus are recommended. The Mach 1 is a single trumpet design
and the Bovus Maximus has two trumpets for even more sound.If you want a new blow-off valve and are concerned about externally venting valves confusing the airflow meter signal to the ECU, GFB does a range of blow-off valves that vent back into the system without changing the airflow meter reading. This range of blow-off valves is called the Plumback. If you still want that sound though, GFB do the Hybrid and Stealth range of blow-off valves. The Stealth has a facility to be able to change from internally venting to externally venting just by turning a dial on the top of the valve. The Hybrid on the other hand is both internally and externally venting, however, the excess pressure is sequentially released - internally first then externally second - with very little or no effect on airflow meter readings.
GFB also manufacture adaptors to fit most Japanese cars or if you prefer they can do the above blow-off valves with adaptors built in for the 2001 Subaru WRX, Nissan Skyline R32, 33 and 34 - also S14 and S15 Sylvia/200SX.
Blitz
Blow-Off Valve. Blitz makes the most affordable Japanese blow-off valve.
Their Super Sound Dual Drive blow-off valve is a lightweight alloy unit with
a twin piston design that gives a loud sequential sound in most applications.
It also has two vent designs one for high volume, the other for low volume sleeper
mode. The Blitz blow-off valve is a very high performance valve, able to hold
up to 30psi.Greddy Blow-Off Valves are available in two types; the type S and type R. The type S blow-off valve is a sequential twin piston design that is recommended by Greddy for any turbo car running up to 20psi boost pressure. The type R valve from Greddy is the best blow-off valve available from Japan. The type R is a super lightweight and strong unit that will hold more than 30psi - also suited for racing. Both type S and type R models are adaptable for internally or externally venting.
As well as the Greddy Type S and Type R, we also have available the Greddy Type RS. This model has been designed to supersede the Type S, but has stronger internals and a more interesting sound. The Type S will however stay in production for the foreseeable future.
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| Greddy Type R |
Greaddy Type RS |
Greddy Type S |
HKS
Super Sequential. The HKS Super Sequential blow-off valve is probably
the world’s most famous. It has a unique shape and sounds like no other
valve on the market. The HKS SSQV has two valves in one: a primary and secondary.
The small primary valve activates ultra quickly for light throttle applications,
then opens both primary and secondary valves for high boost applications.
Turbosmart blow-off valves are an alternative to GFB and available from us at very similar pricing. Turbosmart have an extensive range of blow off valves from the Type 1 and Vee Port to the Dual Port, Supersonic and Megasonic. We also supply Turbosmart’s Kompact Series that is better suited to European turbo cars like the Audi A4 1.8T or Audi S4 2.7 Bi Turbo.