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For purposes of our discussion here, there are two different types of distributorless ignition systems (DIS):
Coil On (or Near) Plug Ignition - As the name implies, there is a coil for each cylinder in the engine. To know which cylinder is firing, both cam and crank timing signals must be received by the ECU.
Waste-Spark Ignition - These can usually be identified by the
two-tower coils. The beauty of waste-spark ignitions is that they do not require
cam timing synchronization. But because they rely on the crank timing only, they
fire two cylinders at once. One is fired in the compression cycle and the second
is fired during the exhaust cycle. Since only one of the two are actually being
fired into an air/fuel mixture, the term "waste spark" is given. UPDATE: As of January 2019 Holley has discontinued all Waste Spark ignition systems. Only replacement components remain available.
Holley's present ignition focus is on their really fantastic Smart Coil. By coupling 8 of these coils with the Smart Coil Harness, you have an essentially plug-and-play high performance coil set for the GM LSx engines. Adding the Universal COP Ignition Harness allows you to connect that to any of the standard Holley EFI main harness ignition connectors. This means you can have COP DIS on virtually any 4-, 6-, or 8-cylinder engine running a Holley EFI ECU (provided you have a cam sync signal, as mentioned above.)
For most applications, a very slight benefit is achieved in Coil On Plug (COP) ignitions. True, the Waste Spark (WS) ignition is wasting a bit of energy by firing into two cylinders, but the coil is typically a bit larger than the normal COP ignition to compensate for that. And for those individuals who have no source of cam timing signal on their engines, the benefit is hardly worth the effort of engineering a working cam timing signal (particularly if fully-sequential fuel injection is not required.)
Holley originally was all-in on the concept of WS DIS. But as techhnology advanced (along with customer expectations) very few WS DIS were being implemented. At the time of this writing, Holley has discontinued their 4-, 6-, and 8-cylinder WS DIS. A limited amount of stock remains. Once sold, a WS DIS can still be achieved by purchasing coils, sensors, and harnesses separately. It will require a bit more custom wiring. Contact us for pre-sale engineering assistance.
The WS DIS kits below require the installer to obtain a Trigger Wheel (sold separately) and mount it and the hall effect sensor (included in the kit.)
If you are planning on running coil-per-plug ignition and haven't already committed to a crank and cam sensor setup, make the smart choice and choose a Holley Dual Sync Distributor to provide your crank and cam sync. Order yours with the smooth-top distributor cover for a clean, finished look!