Im thinking of replaceing the dump valve to a free-flow (open) dump valve. Can i just plug the old hose for the recirculation or do i have to anything else?
is it correct that the original dump-valve on the q4 is manufactured by Weber, or have they replaced mine before? The weber one there is not beautiful at all, plastic and "some" metal, not much but a little bit of metal wink
I have done some research with my local fiat coupe club and they say that the recirculating dump-valve will save your cath, probibly save the turbo a bit and will make the turbo spool up again faster (or not spin down as much) (like 1 thousands of a second wink . A open dump-valve will definitily not give me anything except for the sound, so i will just go with a recirculating one.
I bought the Mitsubishi EVO6 recirculating dump-valve because it was easy to get, cheap (£5.5) and has the reputation to have a very good circulation. I might buy a better looking aluminium dump-valve in some nice color later, but for now the EVO6 one will do just fine.
The hose connections on the EVO6 dump is 34mm but i think the hoses in the Q4 is 23mm, can anyone confirm that they are 25mm or do have to wait until i come home wink ??
Beware.. a waste gate is not a dump valve.
Waste gate is a device that limits boost on the exhaust side, this opens at high engine rpm to limit boost by opening a secondary circuit that bypasses the turbine.
Dump Valve instead gets rid of unwanted compressed charge after the impeller when you don't need it i.e. during a gear change. The recirculating piston valve is best since this charge is recirculated prior to the turbine thus is better defined as being a closed loop cycle with legligible waste. If anyone tries to sell you a dump valve I wouldn't go to them for servicing or engine upgrades because they obviously don't know *****.