Can someone explain to me what the differnt types of dump valve are and what they do?
I see that some people are saying dont get an antmospheric on get a recirc one.
whats this all about? Can anyone be bothered?
Cheers
JAmes
Sure.
When you use your turbo, pressure is built up. Somehow this boost needs to be vented, otherwise the build up would be too much for your turbo and blow it up!
Each time you change gear, the boost neds to be dropped. Basically, an atmospheric dump valve dumps all the pressure to the atmosphere (i.e. outside of the engine), hence the name of the valve.
A recirculating valve dumps the pressure back into the intake system, hence re-circulating it.
If you use an atmos valve on an Ibiza 20vt, the ecu expects the pressure to re-appear in the intake, if not, it thinks there's a boost leak. This is what happens when an atmos valve is used. The engine is not getting teh correct levels of air and fuel, so the engine runs rich.
There's a review/explanation on the main site ;)