Spring options in Diverter Valve questions >
05-21-2004, 06:25 PM
#1
AudiWorld Super User
Thread Starter
Spring options in Diverter Valve questions >
Do the different strength spring options, relate to boost pressure? What's the advantage of using a heavier spirng, and does the rpm range for kick-in correspond to the spring strength (lighter spring, kick in at 3000, for instance, heavier, 4000rpm) or am I completly missing it? Where's a source to read up? thx!
05-21-2004, 06:32 PM
#2
Not really....>>
You want to find the lightest spring that will hold boost yet release easily to prevent compressor stall... You want a quick, smooth release which you won't get with a spring that's too heavy. Think light here. Even a green spring (light) in a Forge DVR will hold boost up to the mid 20 PSI range.
05-21-2004, 06:41 PM
#4
Yes....
I started the shimming thing...Basically a shimmed green is equivalent to a blue. If you're unchipped, go back to a green unshimmed. Try it and see if the car doesn't run better. Shim once and see if it improves. You're running too heavy a spring now....
05-21-2004, 06:48 PM
#6
AudiWorld Super User
Thread Starter
By the way, I get really great kick at about 4000 - 4500 rpm; i guess the green
will drop the cut point to lower rpm, since it will require lower boost pressure to function?
05-21-2004, 06:54 PM
#7
Shouldn't make any difference..>>
Valve is shut from the point the car starts to make boost on up to max. The DV doesn't cycle unless it told to by the ECU through the N249. If it spills boost it's because something is amiss...
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05-21-2004, 07:00 PM
#8
AudiWorld Super User
Thread Starter
I clearly need a better understanding of the way a DV works. Why >
do I want to let uncompressed cold air into the system; I thought the DV was doing it's job by restricting the air (heavier spring), not admitting more of it.
05-21-2004, 07:07 PM
#9
No No..You have it wrong...>
<center><img src="http://images1.fotki.com/v9/photos/7/7305/149094/turbo_schematic-vi.jpg"></center><p>
The DV is a closed system. You're just recirculating air. Think of it this way.
On Boost, you've built up a bunch of pressure. You close the throttle to shift and all that pressurized air has no where to go. Without a DV, it would stall the Compressor, potentially doing damage to the blades and losing all the rotational momentum. WITH a DV, as soon as you lift, vacuum opens the valve, depressurizing the intake tract and rerouting the air back to the compressor inlet. The compressor wheel keeps it's momentum and when you're back on the gas the DV shuts and the turbo is ready to boost immediately....
The DV is a closed system. You're just recirculating air. Think of it this way.
On Boost, you've built up a bunch of pressure. You close the throttle to shift and all that pressurized air has no where to go. Without a DV, it would stall the Compressor, potentially doing damage to the blades and losing all the rotational momentum. WITH a DV, as soon as you lift, vacuum opens the valve, depressurizing the intake tract and rerouting the air back to the compressor inlet. The compressor wheel keeps it's momentum and when you're back on the gas the DV shuts and the turbo is ready to boost immediately....