OK, so what are the limitations of the standard recirc valve. I know we have had the discussions as to the benefit of aftermarket BOV's and that the conclusionis that there is no benefit other than scaring old ladies but there must be a limit for the standard equipment.
In fact, the advantage comes from the lack of turbo spool up time when changing gears up. We estimate a 1 sec time period before the car starts pulling again after gear change when comparing mine to std.
IIRC, the limits of the standard recirc valve are that it will leak boost back to the intake when under high pressures and so you won't be able to hold high boost figures consistently. I think this is the reasoning however someone can coorect me if I'm completely way off the mark.
Maybe u misunderstand the SSQV operating description , it is not controlled by boost pressure but by pressure variations , which then , depending on the amount of variation open either the small primary valve or both the primary and larger secondary valve. Boost pressure actually helps close the valve , so the higher the boost the tighter the seal , it cannot leak either under boost or at idle.
Conventional valves rely only on a spring to provide seal pressure , so the spring needs 2 b heavy which means it is less sensitive 2 throttle variation , ie the throttle needs 2 b fully lifted b4 the valve opens.
The factory valve is not designed 2 cope with higher boost pressures , so the spring is 2 weak 2 seal when boost is raised , also the valve ages quite quickly so will leak even at stock boost levels eventually.
Looks like the Blitz Dual Drive is trying 2 copy the HKS SSQV
ok this is going to be a surprise...but after trying hks, and others i have gone back to the standard one in the standard position
i am however venting it to atmosphere as i am using a map sensor rather than airflow and so stalling/overfuelling is not an issue
i data logged the boost rise and there was actually **NO difference** provided your foot is held flat
i am running 1.7 bar held in the midrange, tapering it down to 1.45 using closed loop boost control
boost presure in the control line will push the standard one closed, so trying to close it you have boost pressure |PLS| spring, against just boost pushing open, also the cylinder at the end works to convert flow in the control line into pressure much like a brake cylinder
you do however need to have your foot flat to hold it closed if you lift slightly/or don't completely floor it the pressure in the control line will drop and it will release air which you can hear escaping
reversing the valve or fitting a decent after market one will cause it to close on part throttle meaning you will get better throttle response and the *appearance* that the car is spooling more quickly, however this makes the throttle less linear and makes the car more difficult to drive if you want to feather the throttle to reduce power a little, you get jolt judder, etc ie the full boost on part throttle problem
the other advantage is that you can keep a good spool on the turbo by letting it vent a bit and then as soon as you floor it it will snap shut and you will get a v fast boost response
please note again that this is operating it vta, the standard recirculate method must cause some turbulence in the intake flow, hot air, flow out the airflow meter, etc etc
also again you *must* have the throttle wide open for it to hold shut
I have got a HKS SSQV and it sounds quite ordinary, ie like a Bailey Dump Valve, but when the HKS Racing Suction Kit went on the next day the HKS SSQV sounds Wicked! sounds like Wastegates when your decelarating.
Theres also a Cruise going down Brighton this Weekend I hear so hopefully I will c some of u guys there!
I have got a Silver Evo 6 Tommi Makinen, with the plate S8 LEO, so look out 4 me!