wastegate 101

[Archbish]

So couple of questions about plumbing wastegates.

I have a dual port wastegate, plus a cheapo boost controller (inc solenoid).  The wastegate is an HKS stylee one with two barbs either side of the piston, and it came with two springs.

When plumbing it all in, I not sure about the following, but think it\'s about right.
1 - the manifold pressure is plumbed in on the exhaust side of the wastegate irrespective.
2 - the manifold pressure is plumbed into the solenoid, and from the solenoid to the wastegate on the side of the piston away from the exhaust.
3 - which spring is used in the wastegate in this setup?  I\'m assuming the weakest one, allowing the manifold pressure to operate the wastegate?
4 - given the proximity of the wastegate to the exhaust downpipe, is it worth using brake line piping to make up some hardlines around the downpipe, only plumbing the silicon where the heat isn\'t?  

Thanks in advance!!

[Prof]

I have a 4 port solenoid if you want to setup the dual port actuator so that it stays shut against exhaust pressure until the solenoid switches it to see boost pressure and start opening.  I\'ve got some plumbing diagrams for that setup somewhere - will dig them out.

[Archbish]

The solenoid install diagram looks to be fairly binary.  There are 3 ports, but they seem to be either one setup for an internal gate, or another for an external gate.

[Prof]

I seem to remember that for internal wastegate it\'s the Normally Open (NO) port on the solenoid valve that connects to the side of the turbo, with the Common (COM) outlet going to the wastegate.  For the external wastegate, COM still goes to the wastegate, but you use the Normally Closed (NC) port on the solenoid to connect up to the boost source.

[Archbish]

that sounds about right!

So what hose have you used to your wastegate, cos I assume it\'s adjacent to a significant heat source - the exhaust??

[Prof]

I did use silicon hose, but the thick walled stuff - the actuator is mounted off the compressor wheel housing - I\'ve got one of those IR thermometers, and that area never gets much about 80 degrees.
 
I know the external wastegates are that bit closer to the exhaust - but you may be suprised - if the exhaust is wrapped it could be cooler than you think.