Carlos13

No guffawing at the back there!

Don't yet have an impreza to examine and am trying to piece together how the whole induction/exhaust system works.

I think I understand the exhaust side - exhaust gases exit to turbo via up pipe, through turbo then along downpipe, through mid section and out the back box.

Its the order of play on the intake side I am unclear on.

I understand that we have air coming in, through the filter, through the MAF sensor (what does this do?) and to the turbo where it is compressed before being fed to the intercooler then on to the inlet manifold.

The dump valve puzzles me. Not its purpose, but its location (in terms of airflow, I know where it is physically located). Does it go between intercooler and inlet manifold (most logical place to me), between airbox and turbo, or does it have an offshoot of its own, say direct from inlet manifold?

I know it doesnt go between the turbo and intercooler as I've seen a single Y piece pipe that makes this link.

Any boffins out there care to help me?

stevebt

iTrader: (8)

here is a dump valve as fitted to a 99/00 impreza, its the big shinny silver thing

Carlos13

Picture implies that it bolts directly onto the intercooler.

However Steve Done's website talks about a rubber hose going from the dump valve to half way back to the air intake...

http://www.steve.ukmail.org/car/ichoses.html

Dyney

That would be for a recirculating DV

The MY93-96 cars have the DV mounted on the Turbo to I/C hose and recirc back t the inlet before the turbo.
The later cars have the DV connected to the IC (like the pic above) and recirc it back to the inlet as the early cars.

If you fit a vent to atmosphere DV then you blank off the recirc pipe and the DV just vents under the bonnet (with a Pssssshhhtttt)

Carlos13

Cheers!