Subarstar

As above, where do I find the existing dump valve on a MY98 UK spec turbo?

I'm trying to locate it as I'm hoping to fit a new Bailey one at the weekend.
I 'm told it's over on the right hand side of the engine, but I'm not sure I'm looking in the right area.

If anyone can point me in the right direction (or direct me to another website) I would really appreciate it.

Thanks in advance,

norry.

markwild

Looking at it as in the pic below - right, front corner of the intercooler - see a rubber hose - its on the end of that - should be a black plastic item.....

Why are you changing it ?

Mark

Subarstar

Mark, thanks for that.
I suspected that's where it was, but wanted to be sure.

There's really no reason to change it, other than I prefer the sound of the VTA to the silence of the recirc. one.
For just now anyway.
(I'll probably get fed up with the whooshing and change it back again!)

Cheers m8,

norry.

john banks

VTAs suck on MAF based ECUs - leaking all over the place usually. Sad boy racer mod, not a performance upgrade. Welcome to the world of bearings lubricated by petrol rather than oil, bore wash, poor fuel consumption and potential engine demise from carbon deposits that can cause pre-ignition and engine failure. Hope you've looked into this one...

Gear Head

iTrader: (2)

So 'all' vta dumpvalves cause the above on every impreza?

john banks

No, but does the average VTA owner have a wideband lambda to tell? Some are horrific, some get away with it. Do they use a borescope to check, and do they look at their plugs frequently? Do they check their oil for lots of fuel?

Maybe I'm stretching the point a bit, but some VTAs are engine breakers. Usually it is an ill informed bling mod.

markwild

I'm certainly going to great lengths to avoid the 'VTA' option - Can't see the logic in spending time and money on making the car accurately measure the incoming air, only to upset that reading by dumping it into the engine bay....

I'm a little confused as to how the 'VTA noise' has become popular too - surely, if you want a 'rally' noise, you need to remove the D/V completely and, ideally, fit anti-lag....

(And rebuild your turbo fairly often....)

John, any idea on the level of downsides to removing the D/V altogether ? (e.g. amount of risk/life reduction on the compressor blades)

norry - I'm sure you'll hear both sides of the story - but I think it ultimately comes down to whether you'd like 'a fast-sounding car', or just a better car ?

Mark

PS _ I found the oem D/V to work well with my FMIC, particularly on partial lift-off.

john banks

TD05 seems OK at least for a while without a DV.

Olly Powers

John,
Which ones are least problematic?
Does the fact that a recirc returns pre-heated air to be heated again have any bearing on it?
Cheers,
Olly

john banks

The air that is recirculated is post intercooler. The dump valve should be shut on full boost. Heating is related to compression of the air, recirculating compressed air reduces the pressure ratio required across the compessor for the same boost. The criminal thing is to heatsoak your intercooler on part throttle by a leaking dump valve to atmosphere because your turbo is working far harder than it needs to.

Olly Powers

Thanks John,

Is there a good way of telling if the dump valve is leaking?
Cheers,
Olly

john banks

It can sound like "blowing over a bottletop" or a "mooing cow" (!)

Gear Head

iTrader: (2)

Just removed my turbo xs dump valve and refitted my standard sti one. Car actually feels smoother and seems to have less lag. Spose this because the air is going back into the intercooler rather to atmosphere. Thanks for all the advice, atleast ive gone through the 'boy racer' phase now!
Now where did I put my baseball cap!