Thread: No boost?
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Raceboy Raceboy is offline
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Join Date: Jun 2009
Location: Estonia, Europe
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Dual chamber boost control is basically when wastegate bottom chamber have the boost reference line directly from intake manifold (it is plumbed like this in stock configuration) and you route second line to the upper chamber and put a boost control solenoid for that.
This way the wastegate can stay completely shut until boost target has been reached which means that boost will build quicker.
Without it, the wastegates start opening already at pressures ~1/3 of target, causing the boost to build up slower and higher.

Control of the solenoid has to be good, because it is easy to get overshoots (when PID algorithm is not tuned correctly). Also the boost solenoid has to have a port configuration where it stays shut when unpowered. This is due to safety.
'83 924 2.5 16v Turbo, 530hp @ 1.5bar
'67 911 widebody hot-rod /2.4S
Old 11-11-2013, 10:44 PM
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