Dump valve / Blow off Valve
 

Quick question for all you out there, 12 months ago at my local garage..... The impreza wrx was in for a service, they took it for a test drive after the service, phoned the wife, (i was in bed offer working a night shift) said the hks blow off valve was impeding performance & might be a fake one, and advised removing it putting back on the stock recirculation valve...(hks was bought new by me from scoobyworld) Which as I don't really understand how it works so to speak said ok....I just want the best fir my beloved car, TBH I don't notice any difference and missed the noise, and more to the point the popping it use to make.... Now I've been chatting with a mate who has a impreza and some mechanical know how... Has said that the blow off valve has no effect on performance at all.... Can you know how clever people tell me who is correct? The garage? Or my mate? Thanks.

Do a "search" above, you'll get all the info you need and more...

I recently did the same , didn't notice any difference other than it now is quiet (and boring IMO).

Mine "popped" once in a blue moon , and I haven't heard it doing it since fitting the recirc. Thats probably a good thing mechanical wise , but I wouldnt know. Some say DVs are bad for the car , but mine had one fitted for the last 6 years or so with no (obvious) damage.

I say fit whichever you prefer the sound off. I'm keeping a hold of my DV so I can fit it when I feel like it.

It will make no benefit to performance, it will however make you sound like a chav and if anything have a negative effect on performance. Although the garage might be wrong about it being fake they are completely right in putting the standard one back on.

unless its mapped in then the popping is the aftermarket dumpvalve causing it to overfuel

A negative effect on performance?

As in overfuelling, poorer idling, jerkier gear changes. The OEM one is fine and up to the job and does not give you any of those problems, albeit you wont get the "chirp" or "dump" which to be honest in this day an age considered to be a bit chavvy. Each to their own though

either way your mate and garage are both partly correct (minus the fake bit)

I had a forge vta on my blob when I got it. I liked the noise (chav at heart) but it was hesitant & jerky at low revs. Put the standard re-circ back on and it drives much better. No kangaroo petrol, a little throttle and it takes off gently as it should.

I think a genuine SSQV sounds the dogs bollocks.
Especially when coupled with a Nur Spec R. :notworthy

As for 'chavvy' I wouldn't worry too much, Impreza's are already considered 'chavvy' full stop.

Thanks for the replys... Glad my garage was correct, as I trust them whole hearted, you guys put my mind at ease....

Not good really as it effects the fueling, the ECU/MAF counts for the air coming back into the system not being 'dumped' out of the system so it can then give the correct mixture.

Should really go mafless, induction kit and remap it all in if you want to go with a dump valve.

IMO of course :thumb: