VTA Dump valves
#1
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I am currently running a Forge VTA dump valve on my 99UK Impreza. I run my car at Crail when I can but I have been told that,not only am I a tart for wanting the chuff noise but it can actually make the car slightly slower! Is this right? Is a recirc valve better for standing quarters? Cheers all
#4
the VTA will only have marginal loss compared to a recirc.
the idea of a DV is to release excess pressure on the turbo when you rev down. As the engine butterfly closes all the air that the turbo (that is spining like mad) has no where to go. it will end up pressurising the system and making the turbo work harder, stalling the turbo. a VTA releases this pressure to tha atmosphere, letting the turbo wind down at its natural rate.
a return valve reflows the air before the turbo. this creates a higher pressure before the turbo, and acts as the exhaust gasses do on the other side, spinning the turbo up.
so, if you understand what i route (which i barley do) then a return valve keepd the turbo spinning at a higher rate, alowing the turbo to spin up quicker... hence the little more performance...
no BHP difference tho (but better curve)
the idea of a DV is to release excess pressure on the turbo when you rev down. As the engine butterfly closes all the air that the turbo (that is spining like mad) has no where to go. it will end up pressurising the system and making the turbo work harder, stalling the turbo. a VTA releases this pressure to tha atmosphere, letting the turbo wind down at its natural rate.
a return valve reflows the air before the turbo. this creates a higher pressure before the turbo, and acts as the exhaust gasses do on the other side, spinning the turbo up.
so, if you understand what i route (which i barley do) then a return valve keepd the turbo spinning at a higher rate, alowing the turbo to spin up quicker... hence the little more performance...
no BHP difference tho (but better curve)
#5
...unless you slam it between the gears (like I'm guessing you would be with what you're talking about), when the boost shouldn't actually have a chance to drop - the effect is that the car keeps pulling when you take your foot off the power. Works well - but not much fun in traffic!
#7
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If you're quick with your changes it doesn't seem to be any different. Of course, I've got the dawes which gets the turbo active very quickly so it feasible this is hidding any Forge disadvantage. Well worth if for the noise
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