Dump or recirc valve

[disco-ian]

OK couldn't find anything on here so going to ask what peoples opinions / logic is on this one.

What's best. Dump (to air) valve or recirc valve.

So the sound of an atmospheric dump valve is cool, but is it better for power to run a recirc valve as the boost is leaked back into the inlet pipe before the turbos and some of this air could of course head towards the turbos and keep them spinning a little??

What say you???

[SGHOM]

you cant beat a good dump ;)

[adaxo]

Get a hybrid one like this http://www.forgemotorsport.com/content.asp?inc=product&cat=0006&product=FMDVSPLTR

joy of nice sound without upsetting ecu much

[disco-ian]

Cool, hybrid looks good.

But anyone know the pros and cons to each of the options.

[Kenneth]

Full recirculating works best, followed by hybrid and then fully vent to atmosphere (VTA).

The pros and cons depend on what you value most.

VTA - Makes noise, can may idle a little rough and ECU isn't so happy when the valve is open
Recirculating - No or little noise but ECU is happy and the car may idle a bit better and use a bit less fuel

A hybrid usually falls somewhere in between those, recirculating enough so that the ECU is happier and won't stall, but will still get incorrect MAF readings while the valve is open.

More important is the quality of the valve, often you get what you pay for and a cheap valve may leak and not run right due to boost leaks etc.

[chris g]

VTA can upset smooth engine running...?

[Kenneth]

Usually only noticeable at idle or transient from deceleration to idle, when the valve is open. The other times (on gear shift) you just wouldn't notice it.


VTA can upset smooth engine running...?

[disco-ian]

I thought the VTA ones had double pistons so they are technically closed at idle as there is no pressure in the induction pipe. There for the air the MAF is seeing would be correct and idle would be O.

That is assuming you are saying poor idle would be because of un mettered air??

[Nick Mann]

AFAIK in all types of dump valve the valve is pushed by a spring, so while the pressure is the same between the reference line and the post-turbo pipework, the spring holds the valve closed. It doesn't matter if the pressure is positive or negative, if the throttle body is open then the pressure is the same, so the valve remains closed. It is the difference across the throttle body that makes the valve operate, which usually only occurs when you close the throttle AND the turbos are creating positive pressure.

As Ken says, valve quality is the most important thing. If you don't get one that is an improvement on stock, why are you getting one at all?

[swinks]

Get yourself stock metal recirc dv from Evo 8/9 MR (FQ) model. You'll be happy :)

[John TheAntique]

You would also be very happy with the Amber Performance one thats on sale here for £60. Just like a good woman, cheap and loud.

[SEAN-NZ]

you can get some pretty loud recirc ones, had comments from mates about how loud mine is, its a greddy one, dont know the model

[Scanny]

has anyone tried the HKS SSQV4? i dont know why but that is the one i want. the biggest issue is finding a genuine one rather than copy

[disco-ian]

Richie. There is one on ebay.co.uk at the moment mate :-)

So if my mast plan is to go MAP, then custom intake to each turbo I guess really I should go VTA as piping up a recirc to twin custom intake pipes is going to be a bit messy.

[Scanny]

they are always on ebay Ian but its a question of whether its the genuine article or not. i certainly wouldnt know by looking at it and im not sure how much i trust a faceless seller. there are a lot of dodgey people around so i will probably by local instead and pay the extra for peace of mind when the time comes. i dont even know what i have on the car now. it might be standard but again, i wouldnt know

[disco-ian]

Looks new, says genuin. Pay by paypal and if it isn't genuine send it back for your money back.

http://www.ebay.co.uk/itm/HKS-SSQV-4-BOV-Subaru-Newage-Adapter-Universal-fitment-NEW-GENUINE-/330908621071?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4d0bb0d90f