Currently from compressor per hahn. Whats your guys thoughts? I've read that going from the manifold actually yields more boost because it's being measured after the psi drop through the IC and piping. I think most people that run external WG have turbos that don't have a port on the compressor housing so they get it from the mani. But then your pulling vacuum through your WG. Where are you guys getting your signals from?
Manifold.
I didn't notice a difference in power or afr between the two though.
"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire
I recommend the manifold.
You can always run a check valve for the vacuum part of it.
FU Tuning
Maybe I'll try it at the manifold out of curiosity. I'm not having any problems now I was just curious how getting the signal before or after the psi drop would affect the turbos response and the engines response. But according to Matt it's nothing noticable which I'm sure is the case.
what do you mean before or after the psi drop? Vacuum is Vacuum no matter where you get it.
Wastegates should not see vacuum. At least internal gates anyway. If the signal comes from the compressor housing the wastegate will open when the spring rate is achieved. So if it's an 8psi spring and you get the signal from the intake manifold, generally there's a drop in pressure from the time it leaves the compressor housing, to the time it reaches the throttle body. So technically for the wastegate to open at 8psi the boost at the compressor housing might actually be 10psi. (Or however much it takes to compensate for the drop). This is the way I percieved it when researching it. Correct me if I'm wrong, so I can know the correct information.
Your theory is correct; the fmic and charge pipes "could" cause a pressure drop between the manifold and the compressor housing.
I have a check valve between the vacuum block (off the manifold) and the MBC. It always was consistent boost. Spike to 35ish and settle at 32ish. I say "ish" because my gauge goes to 30 and the needle keeps going and it's an estimate.
With the alpha-n tune it really doesn't matter because you tune it based on what the afr is and not the pressure and you only change it if you have a tune for that change anyway.
I imagine on a MAP fueled pcm it might matter more. But I have no experience with that, yet.
"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire
