Hei distributed, Multicoil (hei or cdi), Coil per plug – MoTeC M84 User Manual

Page 28: Double ended wasted spark, Ignition system wiring & setup, Distributor button alignment

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26 Installation

MoTeC

HEI Distributed

High Energy Inductive (HEI) distributed ignition systems are generally limited
to about 8000 RPM on an 8 cylinder engine but will run a 6 cylinder to 11,000
RPM and a 4 cylinder to 15,000 RPM.

Most modern road cars run HEI ignition systems that are equally well suited to
high performance engines as long as the above RPM restrictions are
observed.

Multicoil (HEI or CDI)

HEI or CDI multicoil systems will generally run any engine to 15,000 RPM.

Two types of Multicoil systems are possible:

Coil per plug

One coil for each spark plug, fired sequentially.

Double Ended Wasted Spark

Double ended coils have two high tension towers and fire two plugs at
the same time, one on the compression stroke and the other on the
exhaust stroke. Each coil is fired sequentially twice per engine cycle
and must feed the appropriate two cylinders.

Ignition System Wiring & Setup

The wiring and setup parameters are specific to the particular ignition system.
Refer to the appropriate MoTeC Ignition System or Ignition Module drawing.

Distributor Button Alignment

If using a distributor, the button must be aligned so that it is leaving the tower
at Top Dead Centre for that cylinder.

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