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  • Weekend Test drive and those fun sounds

    Over the wekeend I was given a Astra VXR for a test drive (more about that later on this week)but had a question about it. When I owned a modified Astra GTE with a turbo, I didn't need a "dump Valve" as the noise on the re-circ valve was easily heard. On the VXR you can just about hear it and I know all the benefit issues etc etc , but was wondering if anyone has yet to fit one to their VXR, would a touch of fun, of course I would never do it to the Vectra :wink: . I recon I hear the noise louder on my diesel Corsa.

  • #2
    Dump valves are great if you want the noise, however a word of warning.....
    We regularly hear cars with after market dump valves miss-triggering when we are warming the car / rolling road up. When asked, the customers always talk of odd drivabilty and error codes etc.
    The problem is the factory dump valves vacum is operated through vacum storage via a solonoid controlled electronically by the engine management system. This not only release's boost pressure on gear changes, but also can regulate air mass whilst cruising. If you by pass the OE unit and use the same (ECU controlled) trigger pipe on your after market dump valve you will get some strange things happening, When triggered on cruise, the air is blown out externally however the ECU has metered this air this then will affect air fuel ratio. This can bring on error codes for TC and in some cases random misfire codes. This is one example of some of the issues you could have.
    The key is to use a twin piston dump valve and take the trigging boost/ vacuum pipe to a normal vacuum /boost source. This way it will work conventionally and not interfere with the management system.
    The dump valve does not give any power increase, however if it is fitted as above you will not loose any power-torque on cruise. It will just make a big whooshing noise, if this is what you want then go for it.
    If you do not want the noise then the standard in built unit does a great job.
    sigpic
    29 Years as Vauxhall Tuners

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    • #3
      Yea, I had a dump valve on my Astra SRi turbo that used to bring on the TC light what a pain that was ! whist having my car serviced Courtney moved the pipe, problem solved.
      Mind you, took the valve off after about 4 months the noise drove me mad in the end.

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      • #4
        Re: Weekend Test drive and those fun sounds

        Originally posted by Sparky
        Over the wekeend I was given a Astra VXR for a test drive (more about that later on this week)but had a question about it. When I owned a modified Astra GTE with a turbo, I didn't need a "dump Valve" as the noise on the re-circ valve was easily heard. On the VXR you can just about hear it and I know all the benefit issues etc etc , but was wondering if anyone has yet to fit one to their VXR, would a touch of fun, of course I would never do it to the Vectra :wink: . I recon I hear the noise louder on my diesel Corsa.
        stick a K&N on believe me you can hear the dump valve
        ptshhhh!

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