For a two-stroke cycle engine, there may simply be an exhaust outlet and fuel inlet instead of a valve system.

The flat-6 is also smoother than the flat-4 or inline-4 because the power strokes of the cylinders overlap in a four-stroke cycle engine.

In addition, the new plane is likely to require "variable cycle" engines, which operate efficiently at both subsonic and supersonic speeds.

Merlin 2 was to originally have been a gas-generator cycle engine, just like Merlin 1.

The LE-5A was the first expander bleed cycle engine to be put into operational service.

A turbosteamer is a term used by BMW to describe a combined cycle engine.

A second two cycle engine drives the main wheels.

The two cycle engines use a belt-driven propeller speed reduction unit.

Combined cycle engines simultaneously use 2 or more different jet engine operating principles.

Many of them were extensively used by engine manufacturers, including the two cycle engine with piston controlled valves.