A traditional two stroke engine with crankcase scavenging also adopting an exhaust reed valve and lamellar
intake is modified to accommodate a high pressure Compressed Natural Gas (CNG) direct injector and has
the traditional spark plug replaced by a jet ignition device of the same thread. The jet ignition device is
a pre-chamber accommodating a Gasoline Direct Injection (GDI) injector operated with CNG and an 8 mm
racing spark plug. The jet ignition pre-chamber is connected to the main chamber through calibrated orifices.
The CNG is injected after the exhaust post closes. The GDI injector operated with CNG introduces a slightly
rich amount of fuel in the pre-chamber. The spark plug discharge initiates the pre-chamber combustion that
then propagates to the main chamber though multiple jets of high energy partially burned hot combustion
products that quickly ignite the main chamber mixtures. The Computer Aided Design (CAD) model of the
engine including the jet ignition device is discussed in detail. The Computer Aided Engineering (CAE) model
of the engine is shown to produce eciencies well in excess of 35% in the area of best operation. The load
is controlled by fine tuning the injection and ignition events and increasing the overall air-fuel ratio. The
solution oers an opportunity to produce an ecient alternative to four stroke engines with improved power
density, running on alternative fuel having larger availability and better combustion properties and reduced
pollution than traditional diesel and gasoline fuels.