which is a better place to route the vacum line from the WG, to the compressor side of the turbo or to the IM?

 

some say compressor some say im
they say piping+fmic is a restriction so u dont boost the spring pressure when it hits the tb

i run mine T on the im
about to get a vaccum manifold tho

 

explain more on "u don't boost the spring pressure when it hits the tb"

is that if you hook it up to the compressor?

 

something i found while searching:

Surge line: The map width is limited on the left by the surge line. This is basically "stalling" of the air flow at the compressor inlet. With too small a volume flow and too high a pressure ratio, the flow can no longer adhere to the suction side of the blades, with the result that the discharge process is interrupted. The air flow through the compressor is reversed until a stable pressure ratio with positive volume flow rate is reached, the pressure builds up again and the cycle repeats. This flow instability continues at a fixed frequency and the resultant noise is known as "surging".

The best thing you can do to attempt to correct this issue is tap your wastegate before the throttle body. This will allow the wastegate to limit the pressure ratio the compressor is producing hopefully keeping the turbo out of it's surge line. You might see slightly less boost at the intake manifold especially if you have a FMIC, but that can be quickly fixed with a little tweak of the MBC, or EBC if you run one.

Factory turbo cars like the WRX have the WG lines coming from the turbo exit for just this reason, and most RSt's I have worked on / seen have their lines from the manifold . Boost pressure should be read from the manifold I agree, so by all means keep your boost gauge there, but in order to do its job correctly the wastegate line should reflect as close to the actual operation of the turbo as possible

 

i usually go by where you want to the turbo to read boost..just like the guage

 

The wastegate will react to where ever its vac/boost line is referencing. Keep in mind theres always going to be a bit of pressure drop from the piping and intercooler.