trails

iTrader: (41)

Please can anybody help...I remember reading a little while back about a BOV that is silent normally but when playing will swoosh its heart out...but I can't remember who its made by!!

I anyone can remember please let me know or if not general what I should buy advice would be brilliant!!

Dyney

APS do a DV that recircs at low boost but vents to atmos at higher boost. (when playing )

Atmos vent pressure is adjustable too

trails

iTrader: (41)

That sounds like the puppy, any idea how much or a good place to look?

CEL

iTrader: (1)

Maybe it was one of these??

http://www.gofastbits.com.au/

Scoobyclinic sell em... i got the bovus maximus from them on Friday

Chris

greasemonkey

Erm, excuse me if I'm missing something but what is the logic behind running a part recirc/part atmos DV that turns atmospheric when you're pressing on?

The time you most need the fuelling to be right is when you're pressing on, so this is the time you most need the dumpvalve to recirculate...

If you're running a MAP based ECU, it's not an issue, but if you're on the standard one, the best DV, "stealth" or not, is either the standard one, or something else that fully recirculates the dumped air.

trails

iTrader: (41)

Thanks for the info greasemonkey, this is my first tentative investigation into purchasing an aftermarket BOV and my motivation behind the "stealth" option is I would like the ability to keep things quiet as this is my daily drive...

greasemonkey

Serious question Trails: What are you hoping to achieve from your prospective purchase?

The only "benefit" (if you can call it that) of an externally venting dumpvalve is the noise, so if you want to keep things quiet, I can't immediately see why you're thinking of changing from the standard one. Best option would either be to keep the £100+ in your pocket, or spend it on something that will actually help the car's performance.

VTA dumpvalves do not improve the performance of the car, and in fact will most likely reduce it to some degree by introducing fuelling errors.

As mentioned above, you need to ask yourself what you're hoping to achieve from the purchase of an aftermarket valve. In performance terms, the best option is to take the standard DV off and blank its connections, which will give you better throttle response/less lag, but the downside is a theoretical reduction in turbo working life.

trails

iTrader: (41)

Sounds like you have answered my questions for me...but why if it has a detrimental effect on performance do so many people have them fitted?

greasemonkey

Lol, no, haven't answered the question, just asked you to think about what you want from the change! Any answers are your own!

Presumably because most of them want the ability to scare local OAP's and wildlife with the various psshhhhts and similar asthmatic noises, and are either ignorant of, or prepared to ignore the performance/engine health aspects.

There are various bullsh*t stories going around about VTA valves somehow improving performance, but none of these has any basis in fact, and are presumably used as justification (either by the seller or the buyer) for laying out a load of money on a bit of shiny metal that your car neither needs nor benefits from.

trails

iTrader: (41)

Thanks GM...this is the sort of cr*p free response that I was after! Std it is!

CEL

iTrader: (1)

I take it you don't agree with VTA dump valves then greasemonkey?

trails

iTrader: (41)

Whats a VTA (doh) ?

stevem2k

vent to atmosphere

greasemonkey

To be honest chap, I don't know whether I agree with them or not as I've never had a conversation with one, and don't know what their views are!

As to whether I like the idea of one on an Impreza, at end of day it's up to each owner what bits they choose to bolt under their bonnet. If said owner just wants the noise and doesn't care about any other considerations, he/she is going to fit one no matter what anyone else says.

OTOH though, the design of these cars induction and air metering systems means they'll only run optimally with a fully recirculating valve, and that remains the case unless other methods (i.e. MAP based ECU etc.) are used to negate the fuelling errors that result from the combination of MAF based air measurement and a VTA DV.