APC workings - Saab 900 Bulletin Board - Saabnet.com
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APC workings
Posted by Stephen Goldberger [Email] (more from Stephen Goldberger) on Tue, 17 Jan 2006 10:05:49
In Reply to: Help me understand wastegate...., steve, Sun, 15 Jan 2006 17:17:29
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As described correctly by others, the rest position of the wastegate is closed (no waste, all flow through the turbine). There is a spring that holds it closed. Attached to the rod is a pneumatic piston connected to the intake manifold. At a preset level (which is adjustable) the piston begins to open the valve, allowing exhaust to bypass the turbine, thus cutting power to the compressor.
APC bleeds pressure from the piston, fooling it into "thinking" that the manifold pressure is less than it really is. When knock occurs, the bleed is stopped, allowing full manifold pressure to the wastegate control piston to open the wastegate.
Newer Saabs have gotten much more sophisticated, computing the engine state by monitoring pressure, rpm, temperature, and evaluating the combustion process by sensing through the spark plugs, but the concept is still the same.
posted by 24.28.3...
Posts in this Thread:
- Help me understand wastegate...., steve, Sun, 15 Jan 2006 17:17:29
- APC workings, Stephen Goldberger, Tue, 17 Jan 2006 10:05:49 <-- Viewing This Message
- Re: Help me understand wastegate...., CMyles , Sun, 15 Jan 2006 19:33:47
- Re: Help me understand wastegate...., Chaz, Sun, 15 Jan 2006 17:24:11
- yup, vvack0matic , Sun, 15 Jan 2006 17:52:45
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