edar

Hi Guys,

I've just registred with Scoobynet and thought I'd pick your brains. I've owned an '03 WRX 5 door since February and only recently decided to start modifying it. I thought I'd start with a dump valve. Now, I've been told that they're not a good idea, in the fact that it could damage the catalytic converter and ECU (in other words, stay with the factory fitted DV). Although ScoobyWorld seem to sell them without too many issues and claim that they reduce turbo lag, I'm now a little reluctant to buy one as several people have put me off. I realise that they don't do much in terms of performance but it's the novelty factor I'm after - the 'pish' noise in particular. What I need to know is, does an aftermarket dump valve cause any engine damage, and, does anyone have one fitted who can recommend them? I would really appreciate your help.

Thanks
Steve

Splitpin

Welcome. Shops will sell whatever their customers want if there's money to be made so this alone does not indicate that this product is "good".

As for the urban legends you mention, it is not possible to damage the ECU simply via changing the dumpvalve, that's bull. However, the thing about cat damage is, theoretically at least, possible, although it's not something that would happen within hours.

The thing about replacement dumpvalves "reducing lag" is ironically funny, in that the only way one dumpvalve can reduce lag in comparison with another is if it doesn't dump - in other words, stays shut in a context where th other valve would open.

This is why some people choose to remove the valve completely and why WRC cars don't have them in the first place. It is also why some aftermarket DVs come with a range of springs and spacers. If you stiffen the thing up to the point it stays shut, you keep more air in the intercooler and thus it's still in there when you open the throttle again. Of course, under these circumstances, the valve makes less of a noise, and it's that you seem to want, so in practice if you bought an adjustable one and tuned it to scare squirrels with its ridiculous noise, you'd end up with more lag, not less.

If you do remove the dumpvalve completely or shim an adjustable one right up, the reduced dumping then stresses out the turbo and can, sometimes, damage the mass airflow sensor, which is not something you want to happen.

Bottom line is that the factory DV on your car is, from an engine function and design point of view, the best one you could have - and it is better made than almost anything you could replace it with. The people putting you off have a point. If it's novelty factor you want there are plenty of ways of spending the same money that'll make the car tangibly better.

powerwrx

iTrader: (11)

^^^ in a nut shell

if you are to change the dump valve though steer clear of anything cheap... HKS, FORGE,TURBOSMART,GFB are probably the best around..so stick with them.Some people experience running problems when the have a VTA valve fitted, ie dipping revs, flat spots and poor fuel consumption but others have no problems at all..i think its all down to how your car reacts to it.

so choose wisley..

smi565

my brother has a turbosmart supersonic and it has made a difference to his car when its cold it dont idel but when worm its fine and also sounds great

Rickstarbo

One thing that gives you the best of both worlds is a dual vent BOV. This recirculates the gases at low revs, therefore not experiencing stalling issues, but at high revs where it is not going to stall it dumps to atmosphere so you get the dump sound.

There are 2 types I am aware of which would do this, the Turbosmart dual vent and the APS.

I have an APS one available if you are interested.

V5RLTD

iTrader: (5)

Forge also do a split-r dual purpose valve. I have their recirc valve on mine, great bit of kit

-ant-

I had a dv26 it worked with no ill side effects, there was a cheap one on it before that and had problems poor idle, flat spots and hesitation when changing.
The other option is an uprated after market recirc or just the stock one and a good filter and you will get the noises and lots of other nice ones to, but then again the cone filter is just as debateable as the dv.