we have recently bought a 2003 wrx and want to put a dump valve ect onto the car but subaru dealer says no ,is there a reason or are they just being boring if it does no harm can anyone suggest a model that will give a good sound but not make me public enemy number one with the neighbours

 

Welcome to SNet As for dump valves you will hear many conflicting views on them, love or hate.
I am sure people will offer their opinions shortly.

 

I take it you are Chavs?

 

Yes
It can
**** the neighbours, but it'll make you unpopular on here.

Do you realise that your car already has a DV. It's a recirculating model that feeds the air not required when you lift off back into the intake system, balancing out the fuelling and assisting the turbo to spool down properly. BOV's cause brief overfuelling on lift-off by removing metered air from the intake system that the ECU has already accounted and is fuelling for. This overfuelling will make your car run erratically, albeit for a very brief moment. In that moment you will possibly cause bore-wash, where unburnt fuel gets pushed beyond the piston rings, removing the microthin film of lubricating oil and possibly damaging the rings and/or linings, and potentially thining the oil (over time, not a problem with frequent changes). Some of the unburnt fuel will be pushed out down your exhaust, where it causes the affectionately titled "pops & bangs", which used to be known as backfiring and used to be undesireable. These backfires upset valve operation by causing brief negative flow in the exhaust system, and can cause damage to the catalyst. The cat can also be damaged by contamination as it gets coated with fuel. All in all, a pretty ridiculous thing to do when there is absolutely no power gain to be had unless your car is running such high boost that the OE DV cannot cope, just for the sake of a silly noise.

If you want to hear your OE DV and retain smooth running, reliability and performance, research removing the intake resonator. Allied with a decent free-flowing panel filter it will make the whosh of the recirc valve audible (about half as loud as a Chav valve) and also the induction noise. It also seems to make the car run slightly cooler in traffic, and the turbo seems to spool up a little sooner. Takes about 30 minutes to do the mod and costs nothing, except the panel filter if you need it. The money you were going to blow on the silly noise-making valve can be forwarded to me as a thankyou

 

LOL what an answer. Bottom line is that on a MAF sensor based system (standard on Subarus) you need to run a recirculating DV. On a MAP sensor system where the ECU calculates air volume from manifold pressure, inlet temp etc, you can run an atmospheric DV if you want because it the ECU only reads what's right there. If the DV dumps out then that dumped air is not 'counted' hence no problems.

The interesting question is why is it that so many big name Subaru tuners sell atmospheric DVs though when it's common knowledge that it's going to mess up the running of the majority of Imprezas on the roads today? Just take a look at all their websites. Maybe I've not looked hard enough but there seem to be no warnings stating that atmospheric DVs are suitable for only MAP sensor based cars.

 

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thanks for the reply corradoboy i feel suitibly chastised
could you give a little more info on what you described ,is it for bertie basic or someone with more mechanical knowhow

 

Mine was the Bertie Basic version, I think silent running has more technical know-how. For the resonator mod....

 

I think its been proved that removing said snorkel box is a bad idea as it actually robs the car of power

 

agree. i put a dv on and when i lifted my foot off the throtle it felt like my car was being pulled back!!! so i put the original valve back on and it was miles better.

 

Harvey did some tests and I think he found that it did indeed reduce power, but only by a couple of bhp. He didn't test for improved or earlier spool-up which was the more desireable result I found. He also concluded that the OE paper filter seems to give better performance than all the aftermarket lifetime filters. As a compromise to get the sounds so many require, as well as me prefering the way the car ran when I did it, and the fact it costs nothing, it is a much more attractive proposition than a £200 product which will compromise the running of your car and potentially damage it. There's no real good reason to do it, but then there isn't much reason not to. Plenty of reasons not to fit a BOV however.

 

Is this much the same for a classic?

Mine has what appears to be a resonator box fitted between the MAF and turbo?

I Know there is a small pipe down the bottom of the box and would need to be plumbed in.

 

The res is in the O/S wing. On Classic's there isn't a ram-air scoop and the res just pokes out of a hole just behind the O/S headlight, sucking in lovely warm, dirty engine bay air all day. The other end of the res is attached to the filter housing through another hole in the wing. It has to be extracted through the wheel arch and is held in by 2x 10mm nuts. No plumbing required, just remove it, seal around the filter box so it can only draw air from the wing, and seal up all the other holes to the engine bay. Look into opening up a way for more air to get into the wing and don't even consider direct ducting.

 

I'm about to remove an after market BOV from my 04 STi PPP and replace it with the original recirculating model that the previous owner has thoughtfully kept hold of. The original was removed about a year ago and I was wondering if I need to do anything special (cleaning of the original? etc) or is it just a case of a straight swap.