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It is not that intake that is holding you back. The BPC valve is an bleeder valve, electrically variable by the ECU. As with all bleeder valves, there is air pressure applied to the wastegate actuator well before boost is reached. At full boost, the wastegate is open a certain amount, but the valve starts to open well before that point. This means that the wastegate is opening before you get good boost, and you are still waiting for power. When it opens early, the turbine is not getting all of the exhaust flow energy and pressure that could be had. This is not turbo lag, as the turbo is not responsible for this. This is boost lag, caused by the control system.
This is not to say that a stock PBC setup cannot benefit from reduced intake restrictions. You will get some inprovement, but you are still playing the wrong game and re-arranging the deck chairs on the Titanic.
If you install a $35 dawes devices MBC in series with the BCP, then the turbo will spool up much faster. This increase in boost rate will be very significant, much more than increasing the size of the intake. Increasing the intake size will have a greater effect on high CFMs. This type of MBC is not a bleeder valve. It has a simple ball-spring arrangement that prevents the valve from flowing until the pressure gets high enough to unseat the ball. The ball on the seat also creates the flow restriction and the bleed orifice creates the flow that allows the valve to create the pressure drop. All that a boost controller does is created a pressure drop to apply to the wastegate actuator.
There are two approaches.
One is to install the MBC into the input to the BPC, with the bleed orifice of the MBC blocked. The MBC is adjusted to open and then flow at a certain pressure. The MBC is a one way valve. The BPC's bleed port will create the needed bleed down for this one way valve.
OR, You put it between the BPC and the actuator, with the bleed orifice left open. (If you did block the bleed orifice, then the MBC would be a one way valve and the actuator would remain pumped up.
Which works better? I don't know.
This still leaves the PBC and APC functions intact. You adjust it to the point where it wants to increase the boost, but not any higher. If you adjust it too high, the ECU will see the pressure increases and start to close the motor controlled throttle which will prevent any boost gains. And if the ECU sees that it is doing too much of that to keep the pressure down, you will get a CEL.
This does not increase HP, but delivers boost much faster. The vehicle will be much faster and responsive. "Power delayed is power denied"
posted by 208.24.179...
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