Page 30 of Motec Parts Catalog by MoTec

MoTeC Parts Catalogue 2005 Page 30 of 69 Copyright MoTeC Pty Ltd 22/06/2006 Reproduction in whole or in part is prohibited without written approval from MoTeC Pty Ltd Ignition Products CDI versus inductive ignition systems, which should you use? In an inductive ignition system, the coil is charged at battery voltage for a period of time (the dwell time) prior to firing. The dwell or charge time is controlled by the ECU, and this has to be set to match the coil being used so that the coil is not over or under charged. Undercharging reduces available spark energy, while overcharging can cause overheating of the coil and/or ignition module. Inductive ignition systems produce a long spark, at a voltage lower than that of a CDI system. A Capacitor Discharge Ignition (CDI) system is constantly charging itself and sends a large voltage charge to the coil 380- 450v. CDI systems are most often used on boosted or nitrous injected engines. These engines create tremendous cylinder pressures that increase resistance to lighting the ignition spark. Generally, higher cylinder pressures require more voltage to initiate a spark. The arc generated at the spark plug by a CDI system is extremely short in duration, but it is delivered at a much higher voltage than an inductive setup. With an inductive ignition system at higher RPM, it is possible that the time available to charge the coil is less than the time required for a full charge. In this situation you lose coil power and performance, and a CDI setup may be required. The CDI spark is very short, so at leaner mixtures, it can have trouble lighting enough of the intake charge to make the flame front continue though the whole cylinder (this can cause drivability problems). The duration of an inductive spark is longer, enabling it to ignite lots of the mixture to get it started. The basic answer of which setup is best for your engine is, if your engine can run correctly on an inductive setup, then it is better to leave it that way. Install a CDI system only when your engine, due to high RPM or cylinder pressure, requires that you do so. MoTeC Ignition Expander Specifications: The ignition expander uses one ignition output from a MoTeC ECU to send a coded signal that is converted to up to 8 ignition signals. Used for multiple coil situations where ECU outputs are limited. Technical Drawing: A02 14001 IEX Ignition Expander Ignition expander

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