Several S4s using MBCs (in place of the N75) and bypassing N249s are still seeing tapering boost.
05-26-2004, 07:26 AM
#13
as Will suggested it might not be the MBC at all...
if you are losing boost with the wastgate completely closed, there is some other effect causing the tapering boost. a buildup of exhaust gasses in the exhaust or perhaps an intake restriction (not sure about this).
05-26-2004, 11:23 AM
#17
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If the VE of the motor is improved....
then there is less resistance to the incoming air.
Less resistance = less boost, for the same airflow.
That being said, it still doesn't indicate why the MBC isn't working, since the MBC is based off of pressure, not flow.
Less resistance = less boost, for the same airflow.
That being said, it still doesn't indicate why the MBC isn't working, since the MBC is based off of pressure, not flow.
05-26-2004, 11:35 AM
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Yeah. There's a local Stage 3 S4 running similar exhaust configuration to mine...
He's able to maintain ~1.4 bar with the stock boost control system (N75).
-Dave Pramanik
-Dave Pramanik