backwards dv

[psjunkie]

having the boost pushing against the spring ??? So on full boost there's a chance of boost leaking past ?? They shouldn't be run in reverse .

i maybe be wrong but when boosting in theory the boost pressures on either side of the piston will be equal as the small vac line will be under boost pressure too as it comes off the inlet mani plus the spring pressure holding it down will make sureit wont leak???

only an idea

 

[Steely]

having the boost pushing against the spring ??? So on full boost there's a chance of boost leaking past ?? They shouldn't be run in reverse .

under boost the spring does nothing, only on spool when vac side isnt equal to boost acting

vac side of the valve is also pressurised with equal boost pressure,

conventional "piston" dump valves run in reverse,

diaphragm valves, they run this way to create an equilibrium either side of the rubber diaphragm 20psi vac side/20psi valve side, otherwise it'd stress the valve and reduce its longevity, piston type valves dont have this issue,


Personally from my point of view they should run reverse boost acting on the piston, not on the rubber o-rings,

Im a pneumatics engineer by trade so used to talking hot air

 

[Steely]

i maybe be wrong but when boosting in theory the boost pressures on either side of the piston will be equal as the small vac line will be under boost pressure too as it comes off the inlet mani plus the spring pressure holding it down will make sureit wont leak???

only an idea

correct took the words right out my mouth!

 

[psjunkie]

correct took the words right out my mouth!

Whey!!

 

[Dan1720v]

All I'm saying is my findings, in reverse they leak on spool up and loose 20lb/ft in my case.

 

[sambryant]

i'll stick with the bosche one then, i done the n249 bypass and it dumps alot louder now, cheers for input guys, anyone else with any opionions on their DV setup

You shouldnt do the n249 bypass on a stock plastic dump valve, more likely to crack.

 

[draky_uk]

how do u do the n249 bypass

 

[dawson86]

You shouldnt do the n249 bypass on a stock plastic dump valve, more likely to crack.

mine has always run on it and have had no problems, if it cracks i'll get another, but until then i'm leaving it as is! cant see how it will crack? they're good to around 400horses so should hold alot of pressure!

 

[dawson86]

how do u do the n249 bypass

look here, i have put a quick guide with pictures, its for the AUQ code engine so may differe slightly if u have a different engine number?
http://www.seatcupra.net/forums/showthread.php?t=348572