Trebor69

Hello All

My car is currently in API having new engine fitted and when I get it back I want to put a Re-Circ Dump valve on that suits my mods and give a nice quiet whoosh at all rpms etc.

I was running a HKS SSQV which was mounted to the FMIC piping, I fitted re-circ adaptor and fitted a 25mm connector to air housing between MAF and turbo inlet. This worked, albiet still far too loud as running HKS Power flow intake. So I removed SSQV from piping and fitted a 25mm connector in its place.

Then i purchased a single piston forge re-circ valve and fitted this. on Strong springs the noise was a whoosh then a fud dud dud dud noise, idle was ok.. but hated the noise. so went softer springs one by one, noise got lot better more of a whoosh till .7 bar part throttle ..nice... above that too 1.1bar at WOT when coming of throttle got a 'chub' noise then a whoosh then a fud dud dud dud noise... Hmmm ok but not perfect.. but with the softer spring.. when coming up to park, traffic lights etc the car stalls, idles ok from start, just stalls when coming of throttle to a stop.

I tried a 2 piston Atmos and yes, this stopped the stalling problem, noise was crap though and I want re-circ.. Full stop

I then ran a smaller forge re-circ valve, noise was better, still had to run soft spring,, and fell to 200rpm when of throttle but picked back up to 900rpm.

What I am after is a dump valve that will not give me any idle problems and can handle and give a nice single whoosh dump up to 1.2 bar.

I did try fitting a standard subaru dump valve as advised by many on here, no idle problems but above .7 bar again it makes that horrible fud dud dud dud dud noise. This had a inlet/outlet of 20mm so I had to fit adaptors..

Do I need to go bigger inlet/outlet 32MM ??

Do they make a twin valve re-circ?

Why do i get the CHUB - Whoosh -FUD DUD DUD DUD DUD Noise above .7 bar??

What exactly is happening here??? Back pressure on throttle body inlet when it shuts

Dump valve not dumping quick enough...

If someone could please help me out here as this is driving me insane..

I am also wondering if playing with dump valves helped to destroy my engine... David API said sounds like cracked piston... Could the idle dropping down to say 100-200rpm and then kicking back up to 900rpm cause knock??

Looking forward to replies...

Rob
93 WRX - Soon to have STI V9 BLOCK Inc Pistons/crank
HKS FMIC
HKS FCD
HKS Air Intake
VF34 Turbo
Z4 ECU with Uni-chip
3" Full system de-cat
Dawes at 1.1 Will Be fitting EBC when car comes back.

RB5SCOTT

Bob recommends a Forge STI v4 re-circ (they are bigger apparently)

I however have a Forge re-circ that was made for someone else and now i have it, mine is supposed to be bigger still!

Scott

Trebor69

What size inlet/outlet does it have? Is it piston or diaphragm? single or twin?

What boost do you run and what does it sounds loike

Cheers
Rob

RB5SCOTT

I have'nt got my car at the moment but inlets and outlets are the same size (32mm i think)

Think its piston but don't know for sure and that goes for single or twin lol

Sounds like the rally chatter but i think thats more to do with all the other parts rather than dump valve. I'm running 1.5bar

When o get my car back i may take it apart