I've got a MY99 Turbo 2000 UK, running a tek2 and a full decat, last RR was 265hp with a faulty MAF , anyway, I love Dump Valves and had one on my previous car, however I put on a HKS SSQV valve about 6 months ago when the car was standard and could hardly hear it and was then told that it was BAD news from an engine safety perspective.

Recently I've heard more and more subarus with dump valves which sound great and I'm assuming running safely, so is it safe to switch from ReCirc to VTA with my mods or is it generally considered bad news?

 

Forge will be fine. It does send your fuel consumption up a bit. It confuses the MAF as the air that would normally be dumped to the air box, goes to atmos. The MAF gets confused and tells the ECU to shoot a load of fuel in.

I wouldn't bother with any of the overpriced jap ones. I got about 20 miles less on a tank.

Many of the ECU tuning people dislike them, and prefer a recirc.

There are plenty for sale at the mo.

MB

 

I have a forge and according to John Banks (who's advice I have full respect for) its NOT a good idea. I'm just taking a bit of a risk shall we say cause it sounds good

 

HI Kenny

I've got my car back now.

Replaced that PTSSSHHT! sound. With a new (Get your Knickers down! Induction SCHWOOO**** and Recirc whistle.)

See.Hear ya around.

Steve

 

how is a vta 'unsafe'?

I've been told by someone I trust it's nonsense.

Where is the proof?

 

well thats kind of my question

 

To start with the ECU doesn't get confused and throw a load of fuel in. Basically the MAF reads the amount of air going past it and looks off the fuel map to decide how much fuel goes in. If you then lift off some of the air that has gone past the MAF is now no longer in the system so there is less air but the same amount of fuel so the car runs a bit rich. The ECU NEVER puts more fuel in because of a VTA, it runs rich because there is less air.

I had a VTA but replaced it with a Forge recirc, basically because the car feels smoother when you are on and off the throttle (say mid bend). Even with the recirc when i lift off the lambdalink goes rich for a second tho. I wouldn't really worry that much.... the risk is it runs so rich you get bore wash. But i've never really heard of big problems with Subarus. I'd agree with Mark that the jap versions are way way overpriced.... Baileys is a good 'budget' version as too is Forge.

Tony.

 

Interesting, would I get any sound gain from just switching the original part with a Forge recirc?

 

Tony,

Better explaination

MB

 

sg, glad you've got your car back and I hope its running well again after its little episode! Still loving the dump valve especially when you are just driving around not trying to make it sound off and it chirps away of its own accord

I believe the problem is that the overfueling can cause contamination of the engine oil which in turn would put serious stress on some parts and in particular the turbo bearing - thats what I was told. I've never had flames and I have a full decat so mines can't be overfueling that bad

 

UHF

I've just fitted a forge recirc with the stiff (red) spring. The blue spring made the car drive terribly. At low boost/revs you get an odd chirpy whistle type sound from the turbo which is presumably either only a very small amount of "dump" or a toned down version of the WRC chirp due to boost cutting back across the compressor. High boost/revs gives a muffled "ppsshht" due to the valve opening fully, which is still louder than OEM.

Whatever way the car drives better with more part throttle boost and no leakage (my OEM valve was leaking badly above 16.5psi), which will equate to better compressor efficiency/performance.

In summary, definately a worthwhile mod (a bit more sound and better performance, with a quieter knocklink). As for VTA or recirc - probably a matter of preference, but I'm taking enough risks with my engine without adding in another potential confounder.

Cheers

Simon

 

I recently fitted the APS DV to my 02 WRX and this is a wonderful piece of kit. As with some others, it recirculates and VTA's - at lower boost it works like a normal OEM unit but when pressing on you get the whooosh noise (which is what I wanted).

No idle issues although can't comment on overfuel as I've no monitoring gear but the car runs well and I haven't noticed any drop in fuel economy either.

 

I've had the forge VTA fitted for over 12,000 miles now. It does run slightly rich on 'lift off' and pops sometimes, but no idle problems etc. Also had it Tek3'd, and seems fine.

Love the sound, love the way it goes and the mpg isn't bad (better then std), with bigger turbo, 550 jets and pump.

 

Just to add mine pops, bangs and farts (especially on over run) and i have a recirc.

As saxo boy said the problems people see with VTAs are fuel contaminating the oil.... i.e bore wash which i said before. I think that these are still refered to as potential problems because i haven't heard of a single case of this on a Subaru with VTA. Although i satnd to be corrected.

Tony.