..."In the diesel engine, air alone is compressed in the cylinder; then, after the air has been compressed, a charge of fuel is sprayed into the cylinder and ignition is caused by the heat of compression.
"In the two-cycle engine, intake and exhaust take place during part of the compression and power strokes, respectively. ...The blower is provided to force air into the cylinders, for expelling the exhaust gasses, and to supply the cylinders with fresh air for combustion. The row of ports on the on the cylinder wall admit the air as soon as the rim of the piston uncovers the ports. The undirectional flow of air toward the exhaust valves produces a scavaging effect, leaving the cylinders full of clean air when the piston again covers the inlet ports. As the piston continues on the upward stroke, the exhaust valves close and the charge of fresh air is subjected to compression...The fuel is sprayed into the combustion chamber and ignited by the heat generated during compression."
Loosely quoted from the Detroit Diesel Allison Service and/or Operators Manual, Page 4. August, 1980
Love the DD Books as much as the MC8 Manuals