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Originally Posted by dannobee
I know that one of the limitations with inductive ignition systems has always been the dwell time because of a single coil.
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With the proper coil design, i.e. primary inductance/resistance & turns ratio, and using an IGBT switching device, max RPM relative to dwell time is no longer problematic.
Quote:
Originally Posted by dannobee
Did ALL of the manufacturers shy away from CD ignition systems because of cost, or are there other variables in play?
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"Shy away" doesn't properly describe what occurred. Presently, most all OEM automotive manufacturers only use inductive discharge ignitions (IDIs) because;
1. When using a IGBT to drive an IDI coil, the system ECM microcontroller can directly drive the IGBT, basically reducing the old technology CDI design to just one component.
2. Additionally, by eliminating the capacitor of the CDI from the design, system reliability was increased.
3. When using a COP (coil-on-plug) ignition design with a CDI spark design, the ignition ECU cost would be prohibitive.
Quote:
Originally Posted by dannobee
Since we're Porsche specific here, when was the last Porsche CD ignition system used?
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Last used on the '83 911SC.
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Originally Posted by dannobee
Wasn't it in '89?
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No. All Porsche engines beginning with '84 911 3.2 used IDIs.
Quote:
Originally Posted by dannobee
Why did they quit using it?
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Because of significant improvements in semiconductor switching device technology of the late '70s & early '80s, significant cost reductions resulted with improved reliability, when using IDI designs.