Vacuum question

[Blue87T(Dan)]

We have two outlets on the manifold. The one to the left (see the link) is plugged due to the removal of my charcoal canister.

http://www.cygnusx1.net/supra/install/graphics/vacuum_2h.gif

Can I assume it would supply positive pressure under boost if I wanted to use it to hook up directly to my wastegate acutator? The one to the right does not appear to do anything at idle when disconnected (no sucking or blowing).

Thanks

Dan

 

[lagged]

those two ports are on the TB, not the intake manifold.

one is for the EGR, and one is for the charcoal canister.

they both are BEFORE the throttle plate, so, with the TP closed there will be zero vacuum and zero pressure.

underboost the TP is open so itll show you pressure.

using those for the WG actuator ive heard is a bad idea. this is because of the pressure drop from the compressor outlet to the manifold.

the wg will open late.

 

[Blue87T(Dan)]

Thanks.

I thought as much. I am looking for a bit more boost as I have a 14 psi spring already, so I figured I would get the benefit of any pressure drop between the turbo and TB.

I consider the intake anything after the 3000 pipe, but thanks for correcting me so others don't get confused.

Dan

 

[lagged]

yeah id think itll give you more boost doing it like that. cant speak from experience though as ive never done it.

 

[IHI-RHC7]

I've done it.
It works. The only problem is that there is a huge pressure difference between the throttle plate and the intake manifold under partial throttle. If you don't believe me, then hook a boost gauge up to that port, and another gauge up to the intake manifold.
I've seen up to 5 psi in the pipes while the intake manifold is still sitting in vaccum, or right at zero.
It shouldn't cause any problems, it just isn't really accurate under part throttle.
AKA you'll build boost more agressively under partial throttle by refferencing the wastegate from the intake manifold itself, rather than the TB.

 

[Blue87T(Dan)]

Maybe if I tried it from here, tee it off from where it is circled? Excuse my poor paint skills.