[tech] 1.8t - Dump Valve

David.Ullrich at ferguson.com David.Ullrich at ferguson.com
Thu Jun 13 15:09:32 EDT 2002

Sure, I can help with this. I had a Forge on my Passat. Not sure why that site calls it a dump valve, it's really a "Diverter Valve" or DV. It is not the same as a wastegate. The wastegate on your KKK-03 turbo (aka K3) is integral. The DV allows boost to be diverted back to the manifold during times of vacuum. Basically it keeps the turbo spooled up even when you are not "on the boost" without dumping the boost into the atmosphere. It is key to keep the air from dumping into the atmosphere to keep the MAF happy and avoid check engine lights. Anyway, why replace it? Because the stock Bosch DV will fail if you are pumping more than .5 bar into it (1.5 bar including 1 bar atmospheric pressure). They will eventually fail even on stock cars. But when you chip your 1.8T, it is only a matter of time before it dies. When it dies, it starts to leak and some/most of your boost won't make it into the engine. The death of the stock DV can be slow and almost unnoticeable until you compare it to a car with the same mods but a good DV. You end up driving a 1.8 20V instead of a 1.8T.


Too Many Toys:
2002 VW Jetta GLS 1.8T Tiptronic
1993 RX-7 R1
1987.5 Audi Coupe GT "Special Build" 2.3 - Anthracite Black
1985 Chevy Impala SS
1981 Audi 4000 5+5
1982 Audi Coupe
1988 Audi 90 Quattro
1998 VW Passat GLS 1.8T

-----Original Message-----
From: Darrell Adams [mailto:adamsdr at us.ibm.com]
Sent: Thursday, June 13, 2002 1:16 PM
To: quattro at audifans.com
Subject: [tech] 1.8t - Dump Valve

Can anyone explain what this is?

Forge Dump Piston Ram Dump Valve [ Audi/VW 1.8T ]

is this the same as the waste-gate?
why would I want to change this, or not change this?  car is presently
I know my supercharger, but I'm new to turbos.....


'89 90Q
'90 G60 - engine shipping back tomorrow!!!!!
'99 1.8T

Darrell Adams
Configuration Management
External 303-924-8324 Tie 263-8324

"Linux will set you free" - me

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